mineral fertilizer use and the environment.pdf

Mineral Fertilizer Useand the Environment

International Fertilizer Industry AssociationUnited Nations Environment Programme

jjkgkjkgjh

International Fertilizer Industry AssociationUnited Nations Environment Programme

Mineral Fertilizer Useand the Environment

INTERNATIONAL FERTILIZERINDUSTRY ASSOCIATION28, RUE MARBEUF75008 PARIS - FRANCE

TEL: +33 153 930 500FAX: +33 153 930 547EMAIL: [email protected]://www.fertilizer.org

UNITED NATIONS ENVIRONMENT PROGRAMMEDIVISION OF TECHNOLOGY, INDUSTRY ANDECONOMICS39-43, QUAI ANDRE CITROËN75739 PARIS CEDEX 15 - FRANCE

TEL: +33 1 44 37 1450FAX: +33 1 4437 1474EMAIL: [email protected]://www.uneptie.org

Fertilizer Use and the Environmentby K.F. IsherwoodInternational Fertilizer Industry AssociationRevised edition. Paris, February 2000.

The help of Mr. A.E. (Johnny) Johnston, IACR-Rothamsted, U.K., in reviewingand correcting the text is gratefully acknowledged.

Copyright. 1998 IFA. All rights reserved.ISBN: 2-9506299-3-8

The text of the document is available on IFA's Internet site.

Further copies can be obtained from:IFA28, rue Marbeuf75008 Paris, FranceTel: +33 153 930 500Fax: +33 153 930 545 /546 /547Email: [email protected]: http://www.fertilizer.org

Printed in France.Layout: Claudine Aholou-Pütz, IFA

Contents

Preface 5

1. An introduction to mineral fertilizers 71.1. What are fertilizers 71.2. Where are fertilizers used? 71.3. Where are fertilizers produced 8

2. What if? 10

3. The demand for mineral fertilizers 123.1. The future demand for agricultural products 12

4. Economics 14

5. Soils 155.1. Nutrient depletion 155.2. The impact of fertilizers on soil structure 165.3. Soil acidification 165.4. Erosion 17

6. Toxic substances 18

7. Water 197.1. Drinking water 197.2. Surface waters 207.3. Potash 20

8. Air 218.1. Ammonia 218.2. Greenhouse gases 21

9. Nutrient losses and efficiency 239.1. Nitrogen 239.2. Phosphate and potash 259.3. Products 259.4. The efficient use of fertilizers 279.5. Fertigation 279.6. Balanced fertilization 279.7. Site specific fertilizer application 28

10. Integrated systems 2910.1. Integrated farming 2910.2. Land planning 2910.3. Ferti-Mieux 3010.4. Integrated plant nutrition systems, IPNS 3010.5. Leguminous plants as a source of N 30

11. Nutrient accounting 32

12. Health 3312.1. Human health 3312.2. Plant health 34

13. Biodiversity 35

14. Organic materials 3714.1. Temperate and cold climate zones 3714.2. Tropical and subtropical zones 3814.3. Composts 39

15. Resources 4015.1. Resource availability 4015.2. Recycling 42

16. Land spared 44

17. Partners in environmentally sustainable fertilizer use 45

Selected references 47

About IFA and UNEP 51

Mineral Fertilizer Use and the Environment 5

Preface

retaining benefits. The use of fertilizers is noexception, but both the policy maker and thefarmer must have the necessary knowledge.Farmers must know how to use fertilizersefficiently under their own particularcircumstances. Most of the adverse effects offertilizer use result from inadequate knowledgeamong farmers.

The review highlights the importance of usingmineral fertilizers efficiently. Inefficient use notonly increases their negative environmentalimpact unnecessarily, but also represents a largewaste of natural resources and a substantialeconomic loss.

To improve the efficiency of fertilizer use is amajor challenge. There is also scope for improvedproducts, but the greatest medium-term gaincould be had from improving the way in whichcurrently available fertilizers are used. Manytechniques for achieving this are known, butoften they are not put into practice. The task ofcommunicating information on the correcttechniques to farmers, and of persuading them toadopt them, is formidable. Of the worldpopulation of 5.7 billion in 1995, the agriculturalpopulation accounted for 2.6 billion.

This document aims to present a balanced viewof, on the one hand, the benefits of using mineralfertilizers and on the other hand theenvironmental risks involved. It is not intended tobe a scientific document, but it aims to betechnically correct.

Chapter 14 of Agenda 21, agreed at theUNCED “Earth Summit” held in Brazil in 1992,states “The world’s capacity to feed a growingpopulation is uncertain ...agriculture has to meet thechallenge mainly by increasing food production onland that is already in use, and avoid encroachmenton land that is only marginally suitable forcultivation”.

This review presents the evidence supportingthe view that the use of mineral fertilizers is anecessary condition for achieving theseobjectives. Their use is necessary but they dohave an impact on the soil, water, air, plant andhuman health.

All human activities affect the naturalenvironment either adversely or beneficially; andwhat is adverse or beneficial may depend onone’s point of view. The long-term sustainabilityof any system requires complicated trade-offsbetween benefits and losses. Almost always,there are ways of minimizing losses while

Jacqueline Aloisi de LarderelDirectorUNEP Division of Technology, Industry andEconomics.

Luc M. MaeneDirector GeneralInternational Fertilizer Industry Association (IFA).

6 Mineral Fertilizer Use and the Environment

Note: In this document:

• Mt = million tonnes

• Kt = thousand tonnes

• Mha = million ha

• Phosphate and potash may be expressed as their elemental forms P and K, or as their oxideforms, P2O5 and K2O. Nitrogen is expressed as N.


1. An introduction to mineral fertilizers

• improve unfavourable or to maintain goodsoil conditions for cropping.

The existence of a close relationship betweenfertilizer consumption levels and agriculturalproductivity has been established beyond doubt.Amongst the various agricultural inputs,fertilizers, perhaps next only to water, contributethe most to increasing agricultural production.

In this publication, the term “mineral”fertilizer is used in preference to terms such as“chemical”, “artificial” or “synthetic” fertilizers.Apart from nitrogenous fertilizers, they are, infact, more or less purified minerals. In the caseof nitrogen, approximately 99% of the totalsupply is produced from ammonia, which ismanufactured from the abundant atmosphericnitrogen reacted with hydrogen.

1.2. Where are fertilizersused?

The use of fertilizers as a regular farming practicebegan in most European countries in the mid tolate nineteenth century but the greatest increasein consumption in these countries occurred in thethree decades following World War II. Theirincreasing use in the developing countries startedin the 1960s.

In 1960, 87% of the world fertilizerconsumption was accounted for by the developedcountries, including the USSR and the countriesof Central Europe. From 1980 to 1990consumption tended to stabilize in these regions,apart from the USSR, where it increased until1988. Population growth had leveled off, almosteveryone was adequately fed, world agriculturalexports had stagnated due to economic problemsin the importing countries and on well managedfarms the economic optimum of the availablevarieties had been reached.

1.1. What are fertilizers

Mineral fertilizers are materials, either natural ormanufactured, containing nutrients essential forthe normal growth and development of plants.Plant nutrients are food for plants some of whichare used directly for human food, others to feedanimals, supply natural fibres or produce timber.Man and all animals depend entirely on plants tolive and reproduce. The public perception ofmineral fertilizers often takes no account of thesesimple facts.

Three plant nutrients have to be applied inlarge quantities, nitrogen, phosphorus andpotassium. Sulphur, calcium and magnesium alsoare required in substantial amounts. Thesenutrients are constituents of many plantcomponents such as proteins, nucleic acids andchlorophyll, and are essential for processes suchas energy transfer, maintenance of internalpressure and enzyme action. Seven otherelements are required in small or trace quantitiesand are referred to as “micronutrients” or “traceelements”. A further five elements are requiredby certain plants. These elements have a varietyof essential functions in plant metabolism. Themetals are constituents of enzymes controllingplant processes. The deficiency of any onenutrient can compromise the development of theplant.

Mineral fertilizers comprise naturallyoccurring elements which are essential to life.They give life and are not biocides. Fertilizers areused in order to:• supplement the natural soil nutrient supply in

order to satisfy the demand of crops with ahigh yield potential and produce economicallyviable yields,

• compensate for the nutrients lost by theremoval of plant products or by leaching orgaseous loss,


Between 1989 and 1994 fertilizerconsumption in developed countries as a wholefell from some 84 Mt nutrient in 1988 to 52 Mtnutrient in 1994. The fall was greatest, by 80%in total, in the formerly communist countries ofCentral Europe and the former Soviet Union(FSU). Crop production in this region also fell,although not to the same extent. This wasbecause under the centrally planned systemfertilizers were used inefficiently and plantavailable reserves of some nutrients hadaccumulated in the soil and could now be minedto help feed crops.

In developing countries until the 1960sfertilizers were applied mostly to plantation cropssuch as tea, coffee, oil-palm, tobacco and rubber,while application to field crops was either smallor non-existent. Even where fertilizers wereapplied, application rates had to be small in viewof the traditional tall cereal varieties which werecultivated at that time. The introduction of high-yielding, fertilizer-responsive dwarf varieties inthe mid to late sixties gave a considerable boostto fertilizer consumption applied to annual fieldcrops. Unfortunately this development has stillnot occurred in many countries of sub-SaharanAfrica, for economic and climatic reasons andalso for lack of suitable varieties.

Since 1960, fertilizer consumption in thedeveloping countries has increased more or lesscontinuously, and today accounts for about 60%of the world total, compared with 12% in 1960,a trend which is continuing. With their rapidlyincreasing populations, many developingcountries are compelled to give agriculturalproduction and the development of fertilizer usea high priority.

Between 1993/94 and 1997/98 world totalfertilizer nutrient consumption increased from120 to 136 Mt, an average rate of increase ofabout 3% p.a. Consumption in China, South Asiaand Latin America increased by 10, 5 and 2 Mtrespectively. But in most countries of sub-SaharanAfrica the quantity of fertilizer used is not onlyvery low, but also most of what is used is applied

in the commercial, plantation sector. Rates offertilizer use on food crops are particularly low.There is a very large variation in application ratesbetween countries, as is shown by the examplesin the following table.

1.3. Where are fertilizersproduced

Increasingly the manufacture of fertilizers is aglobal industry, located near the source of theraw materials or in developing countries withexpanding markets for the products. Fertilizerproduction is decidedly not a monopoly of thedeveloped world.

1.3.1. Nitrogen fertilizers

The energy required for nitrogen fertilizerproduction is found around the planet and thereis production in every region of the world.However, there has been a trend towardsincreased production not only in locations wherecheap natural gas is available, such as the MiddleEast and the Caribbean, but also in the mainconsuming regions, such as South Asia andChina.

Average rates of application

Source : Fertilizer Use by Crop. FAO/IFA/IFDC. 1996

RateKg nutrients per ha

Russia 25France 240Wheat

Korea Rep. 320Cambodia 4

Rice

USA 257Tanzania 12

Maize

Tadjikistan 461Benin 45

Cotton

of N + P2O5 + K2O

Rates of fertilizer use in the Russian Federationhave fallen greatly since 1989.


1.3.2. Phosphate

The main producers of phosphate rock andphosphate fertilizers are the USA, the FSU, China,Africa and the Middle East. Several of thesecountries are developing countries and thephosphate industry makes an importantcontribution to their economies.

Over the past two decades there has been adistinct trend towards the processing ofphosphate rock in countries with substantialnatural resources of this material, especially inNorth Africa and the USA, but also in the MiddleEast and South and West Africa. There havebeen several plant closures in West Europe,

where phosphoric acid production capacity andoutput have fallen by 60% since 1980, foreconomic and environmental reasons, particularlythe problem of gypsum disposal.

1.3.3. Potash

Potash is produced in the few countries wherethe ores are located. In 1996 Russia and Belarusaccounted for 23% of the world’s production,Canada for 35%, West Europe for 23% andIsrael and Jordan for 11%, these few regions thusaccounting for a total of 92% of worldproduction.


2. What if?

In France in 1850 the average wheat yieldwas 1000 kg/ha. By 1950 it had reached1600 kg/ha with a fertilizer consumption of1.1 Mt total nutrient. By 1973 the average yieldwas almost 4500 kg/ha, fertilizer consumption5.8 Mt nutrient, of which 1.8 Mt was N. Theaverage yield between 1994 and 1996 was6772 kg/ha with the consumption of 4.8 Mtnutrient, of which 2.4 Mt was N. In France therehas been a close correlation between theproduction of cereals and nitrogen deliveries. Theeffect was made possible by the use of acombination of all the means of production,species and varieties with a high genetic potential,grown on well prepared soil, protected againstpests and diseases. Annual yield variations wereminimized and production costs reduced. At1950 yields it is estimated that a householdwould still spend 50% of its income on foodcompared with 20% today. France is now thesecond largest world exporter of agricultural andderived products.

It is sometime salutary, when advocating thetermination of some technical advance, to lookback at the situation before the advanceoccurred. Price (1993) described the situation inFrance until the nineteenth century. Prosperity ormisery, life or death depended on a good harvest.The last major famine in France was in the early1700s although “crises de subsistence”, whencereal prices increased by 50% to 150%,continued to occur until the mid 1800s. Thecrises of 1788-89 and 1846-7 were particularlynotable in terms of their economic, social andpolitical impact, both preceding popular revolt.

In China, using organic matter to maintain thefertility of the land, rice yields were maintained at700 kg/ha for thousands of years. During thepast 40 to 50 years, using a combination ofavailable organic materials and an ever-increasing

What would happen if mineral fertilizers werenot used?

The immediate effect of terminating the useof mineral fertilizers is that crop yields would fallto levels sustainable by the soil alone and therelatively small net inputs through organicmaterials, and that the yields would fallprogressively as the soil nutrient reserves areused up, declining eventually to the low levelsobserved in very long-term trials. In the absenceof fertilizers it is likely that cropping systems andmanagement methods would change, but despiteall the efforts, it is inevitable that the presentstructure and output of agriculture could not bemaintained. There would simply be insufficientcrop nutrients in the overall system. The richercountries may possibly get by but not the poorercountries, and perhaps not the poor in richercountries.

Schmitz and Hartmann (1994) establishedmodels to make quantitative estimates of theeffect of reducing the use of agro-chemicals,including nitrogen, in Germany. They calculatedthat halving the fertilizer nitrogen applicationwould lead to a 22% reduction of yields in theshort-term, 25 to 30% in the medium term, farmprofits reduced by about 40%, farm income by12%, total cereal production reduced by 10%,with a substantial impact on employment inagriculture and the food processing industries,reduced agricultural exports, increased imports,and an increase of the world price of cereals of5%. For limited reductions in nitrogen use, someecological benefits would be obtained rapidly but,with across-the-board extensification, the gainswould fall and even turn into losses, with areduction in woodlands and wetlands as thesewere brought into cultivation. If this is theposition in Germany, what should it be in lessindustrialized countries?


input of mineral fertilizers, yields have multipliedsix-fold, to reach an average, between 1994 and1996, of 5958 kg/ha.

A. Subba Rao and Sanjay Srivastava (1998)wrote Fertilizers have played a very prominent rolein Indian agriculture. From a mere 0.13 Mt in1955-56, fertilizer consumption has increaseddramatically over the last four decades to reach 14.3Mt in 1996-97. As a consequence of the growingdemand for foodgrain, fibre, fuel and fodder to meetthe needs of an ever increasing population, fertilizerconsumption is increasing annually. Thecontribution of fertilizers to total grain production inIndia has been remarkable; from one per cent in1950 to 58 per cent in 1995. According to M.Velayutham, the contribution of fertilizer toadditional food production was about 60 per cent.Fertilizer consumption and agricultural productionshowed phenomenal growth during the period 1951to 1995. The present concern is to ensure thesustainability of crop yields, a safe environment andprofitability for the poor farmer with increasedfertilizer use.

In general, it is difficult to estimate thecontribution of mineral fertilizers to globalagricultural production in view of the interactionof the many factors involved in this biologicalprocess. An IFA survey covering developedcountries carried out in the 1970s indicated thatyields would fall rapidly by some 40% to 50% iffertilizers were no longer applied. According tosome Chinese data, fertilizers contribute 40% to50% of the grain yield, 47% of the cotton yield.V. Smil (1999) estimated that, globally, 40% ofthe protein in the human diet is derived fromnitrogen fixed by the Haber-Bosch process for themanufacture of ammonia.

In Japan, A. Suzuki (1997) reports thatsurveys made in 1990 at 92 experimental sites

showed that the national average yield obtainedwithout nitrogen applied for several years was70% of the fertilized plots. Yields decreasedgradually over the years. In a long-term trial, after50 years of NPK fertilization there was nodecrease over the years in the fertilized plots. Theyield without fertilizer was about 40% of that ofthe fertilized plot.

Mackenzie and Taureau (1997) gave a typicalyield response curve of winter wheat to fertilizernitrogen in the UK. Even at the economicoptimum, where the value of the additional unitof nitrogen equals the value of the crop obtainedtherefrom, the response was 3 kg grain per kg N.Without nitrogen the yield would have been 4 t/ha instead of 7 t/ha at the economic optimum.From another series of trials in the UK quoted bythe same authors, it was estimated that the yieldof wheat increased by 24 kg of grain for every 1kg of N fertilizers up to the stage where theresponse started to plateau.

Based on a wide range of experiments in alarge number of countries, the FAO consideredthat “it is reasonable to assume that 1 kg offertilizer nutrient (N+P2O5 +K2O) producesaround 10 kg of cereal grains” (FAO, 1984).

K.K.M. Nambiar (1994) summarizes resultsfrom long-term trials in India, from which thefollowing is an extract:

* Average of three locations

Rice* 1751 3607 3994

Wheat** 994 3342 3545

Yields(kg/ha)

Nofertilizers

NPK NPK + FYM

** Average of four locations


3. The demand for mineral fertilizers

3.1.2. Income

According to the International Food PolicyResearch Institute (IFPRI, 1997), between 1993and 2020, the global demand for cereals isexpected to increase by 41%. The developingcountries’ demand for cereals for feeding tolivestock is expected to double, while demand fordirect human consumption is expected to rise by47%, although the largest absolute increase willbe greater for the latter. There will be similarlarge increases in the demand for other crops.Global income growth is projected to average2.7% per year between 1993 and 2020, thegrowth rate in developing countries being almosttwice that of developed countries. Economicgrowth, rising incomes and urbanization,particularly in Asia and Latin America, areleading to rapid changes in diets, in favour ofmore grain-intensive food such as meat,particularly red meat. This leads to a substantialincrease in the demand for grain to feedlivestock, the impact on cereal requirementsbeing magnified by the rather low feedconversion efficiency of livestock. IFPRI (1999)estimates that the world's farmers will have toproduce 40% more grain in 2020, comparedwith 1995. However, the expansion of the cerealarea is unlikely to be more than 5%, almost twothirds of which will be in the difficult region ofsub-Saharan Africa. Inevitably most of the higherproduction must come from higher yields per unitarea, which will require a correspondingly largerquantity of plant nutrients, from one source oranother.

3.1. The future demand foragricultural products

3.1.1. Population

Between today and, say, 2020, the world’spopulation is going to increase, mostly in thedeveloping countries. According to the WorldBank’s 1994-1995 population projections, theworld’s population will increase from 5.7 billionpeople in 1995 to 7 billion in 2020. Thisincludes increases in China from 1.2 to almost1.5 billion, South Asia from 1.3 to 1.9 billion,Africa from 0.7 to 1.2 billion. The rate ofincrease is likely to be highest in Africa but inview of the large population base in South Asiaand China, there will inevitably be a substantialincrease in these regions. IFPRI (1999) estimatesthat developing countries will account for about85% of the increase in the global demand forcereals and meat between 1995 and 2020.

FAO projects that 680 million people, 12% ofthe world’s population, could be chronicallyunder-nourished in 2010, down from 840million in 1990-92 but still a very substantialnumber. 70% of these will be in sub-SaharanAfrica and South Asia, especially Bangladesh.

In Africa and the Near East, the absolutenumber of hungry people will increase, thoughthe proportion of the population that isundernourished will decline. Many of thesepeople are the rural poor, who lack the buyingpower to satisfy their nutritional needs, evenwhen the supplies exist. Women and children aremost affected. The issue in their case is todevelop agricultural systems which will providethem with sustenance and income.


3.1.3. Fertilizers and food

The exact contribution of mineral fertilizers toagricultural production is debatable but in anycase the millions of field trials which have beencarried out throughout the world demonstrateclearly their great influence on crop yields.

In an article in “The Observer”, New Delhi,April 17, 1997, Dr. Swaminathan, a leadingIndian scientist, is reported as saying thatFertilizer is the key to securing the food need of morethan 1.3 billion Indians by the year 2025. Nocountry has been able to increase agriculturalproductivity without expanding the use of chemicalfertilizers. Working on a conservative populationforecast of 1.3 billion by 2025, India would need30 to 35 million tonnes of NPK from chemicalfertilizers in addition to 10 million tonnes fromorganic and biofertilizer sources, to produce theminimum food grain need of 300 million tonnes.Scientists have found that there was growing evidenceof the increasing deficiency of phosphate and potashin soils, aggravated by the disproportionateapplication of higher doses of N in relation to P andK. Sulphur has been identified as crucial for

optimizing the yield from oilseeds, pulses, legumesand high-yielding cereals.

N. E. Borlaug, a Nobel Prize winner, (1997),speaking of Africa, stated: “My 53 years ofexperience in low-income developing countries tellsme that small-scale farmers are loath to adopt such“low-input, low-output” technologies since they tendto perpetuate human drudgery and the risk of hunger.This certainly has been our experience in Sasakawa-Global 2000, where farmers have overwhelminglytold us they want access to yield- increasing,drudgery-reducing technology, and have proven thatthey are able and enthusiastically willing tomodernize their production”.

Several institutions, among them the FAO,IFPRI, UNDP, the US Department of Agricultureand the World Bank, have made projectionsconcerning food security. They differ according tothe assumptions made, but essentially they are inagreement that the world supply of food will haveto keep growing, and growing rapidly.Agricultural investment, especially in researchand advisory services, will be essential if theobjective is to be achieved.


4. Economics

Economic growth is strongly linked to povertyreduction. Poverty is itself a form of pollution and,in addition, the poor are often forced to overuseor misuse the natural resource base, in order tomeet their basic needs.

Another, February 1994, IFPRI reportdescribed the results of a study in seven Asiancountries, with widely diverse productionenvironments and agrarian and policy structures,of the effect of technological change in favourablerice-growing areas, on the income of people inunfavourable ones - those by-passed by the newtechnology. The contributors found that whenindirect effects of labour, land and productmarket adjustments are taken into account,differential adoption of high yielding varieties,HYVs, across environments does not significantlyworsen income distribution. As HYV adoptionincreased the demand for labour in thefavourable areas, more inter-regional migrationfrom unfavorable areas took place, whichmitigated potentially negative effects byequalizing regional wages. Shifts to alternativecrops or non-farm employment in the unfavorableareas also contributed to equity.

A 1997 report by the Indian National Councilof Applied Economic Research states that Indiacould virtually eliminate urban poverty in adecade if it could sustain an annual economicgrowth averaging 6.4%. But the report alsoforesees growing disparities between Indian citiesand the countryside where 74% of people live.Agricultural growth is stagnant. The reportsuggests that the urban 26% of the populationwill increase to 30% in 2007 but this does nottake account of possible accelerated urbanizationprompted by the rising income disparities.

There is today a wide agreement that anecessary condition for economic growth in mostdeveloping countries is a productive agriculture -there are some exceptions, but they are few. Thiswas not always the case. In the 1950s theemphasis in development policy was on urbanindustrial growth, with the agricultural sectorbeing regarded as a source of inputs, mainlylabour, for the manufacturing sector. It was onlyin the 1960s that the positive role of agricultureas an engine of development became accepted.Subsequent events in the 1970s and 1980sreinforced the need for more attention to be paidto agricultural development policies. But eventoday, some developing countries still do notattach sufficient importance to agriculturaldevelopment. If agriculture is to be productive, itis evident that the crops should receive, from onesource or another, the nutrients they require.

A June 1996 IFPRI study concerning LatinAmerica confirmed how agricultural growthhelps the whole economy. When agriculturalproducers’ incomes rise, they spend money onnon-agricultural items, creating jobs for othersthroughout the whole economy. The study foundthat for every US$ 1 increase in agriculturaloutput in developing countries, the overalleconomy grows by US$ 2.3.

Apart from being good for the nationaleconomy, productive agriculture helps toalleviate rural poverty. Most of the world’s poorare rural-based and, even when they are notengaged in their own agricultural activities, theyrely on non-farm employment and income thatdepend directly or indirectly on agriculture. Therural poor make up more than 75% of the poorin many sub-Saharan and Asian countries.


5. Soils

food security and to the lives and livelihoods ofmillions of people. The loss of fertility reduces yieldsand affects water holding capacity, leading to greatervulnerability to drought.” (FAO press release, April1990).

A fertile and productive soil is thefundamental resource for the farmer and theentire ecosystem. The farmer’s objective is tomaintain the productivity of his soil. This impliesthe need for good stewardship on his part; that is,maintaining a good physical structure, organicmatter content, good aeration, an adequatemoisture content, proper pH and an optimalnutrient status. Management of such a system iscomplex. The sequence of crops grown, thenumber of livestock carried on the farm and thecultivation techniques employed by the farmercan either reduce or improve soil productivity.

As regards the plant nutrients, a crop’s overalldemand and the amount removed from the soilmust be replaced, not necessarily annually, butcertainly within the overall crop rotation, if soilfertility levels and long-term productivity(sustainability) are to be maintained.

The following paragraph is quoted from anIFPRI report on The World Food Situationpublished in October 1997.

“Past and current failures to replenish soilnutrients in many countries must be rectified throughthe balanced and efficient use of sources of plantnutrients and through improved soil managementpractices. While some of the plant nutrientrequirements can be met through the application oforganic materials available on the farm or in thecommunity, such materials are insufficient toreplenish the plant nutrients removed from the soils.It is critical that fertilizer use be expanded in thosecountries where a large share of the population is

As stated by A.E. Johnston (1997) soil fertilitydepends on complex, and often little understood,interactions between the biological, chemical andphysical properties of soil. Understanding andquantifying interactions between the biological,chemical and physical properties of soil willbecome ever more important. He observes that itwill be necessary in future to recognize moreclearly that there is a distinction between theagricultural productivity and the fertility of a soil:

• Provided soil fertility is at a satisfactory level,within climatic constraints agriculturalproductivity may be controlled by annualinputs like N and chemicals to control weeds,pests and diseases.

• But soil fertility is frequently controlled byfactors which are often difficult to manipulatein the short term, for example, chemicalproperties like soil acidity and plant nutrientstatus.

Wherever possible it will be necessary todefine critical measures of soil fertility, and thenensure that soils are kept just above them. Belowthe critical value, loss of yield is a seriousfinancial threat to the sustainability of anyhusbandry system. Maintaining soils much abovethe critical value is an unnecessary financial costto the farmer and may have environmentalimplications.

5.1. Nutrient depletion

“The loss of soil fertility in many developingcountries poses an immediate threat to foodproduction and could result in a catastrophe no lessserious than from other forms of environmentaldegradation”. “Agricultural soils lose their fertility byplant nutrient depletion and, in some cases, plantnutrient exhaustion.....a real and immediate threat to


food insecure. One of the largest environmentalproblems in Africa today is the gradual decline in thefertility of much of the soil”.

The mining of nutrients is part of the cost ofproducing crops, often a hidden cost which is notpassed on to the consumer. Under suchcircumstances, the use of public funds to helpreplace the mined nutrients may be justified,especially in situations where the farmer’sfinancial situation is precarious.

5.2. The impact of fertilizerson soil structure

It is sometimes claimed that the use of mineralfertilizers has an adverse effect on soil structure.Evidence from very long-term experimentsindicates that this is not the case. The aggregatingaction from enhanced root proliferation andgreater amount of decaying residues from wellfertilized crops makes soils more friable, easier tocultivate and more receptive to water. S.W. Buoland M.L. Stokes (1997) state “Organic carboncontents that become lower under inadequatefertilization appear to recover when adequatefertilizer is applied. Adequate fertilization alsocontributes to greater biomass production tending toprotect soil from erosion and providing greaterquantities of residue critical to soil aggregation. Wetherefore conclude that long-term, high-inputagriculture has a strong positive effect in improvingagronomic properties of soils”. Field plots at theRothamsted Experimental Station in the UnitedKingdom, which have received chemicalfertilizers since 1843, are more productive todaythan at any time in the recorded past. At theAskov experimental station in Denmark, after 90years, the plots receiving NPK fertilizers had an11% higher organic C content than the controlplots. The increase in organic matter contentinduced by NPK applications resulted in adecrease in soil bulk density and a concomitantincrease in total porosity (R.J. Haynes and R.Naidu (1998). They conclude that “The long-termpositive effect of continual application of fertilizer

materials on soil organic matter content and soilphysical conditions is an important, although oftenneglected, factor that needs to be considered whencontemplating sustainability”. In Japan (A. Suzuki,1997) after 50 years of NPK fertilization therewas no decrease over the years in the fertilizedplots. The yield without fertilizer was about 40%of that of the fertilized plot.

5.3. Soil acidification

Most nitrogen fertilizers, especially ammoniumsulphate and to a lesser extent ammoniumnitrate, acidify soils, although some soils arenaturally able to cope. The use of organicresidues at normal levels of application may notavoid acidification but may slow the process.

The acidifying effects of nitrogen fertilizer canbe corrected if lime is economically available andis applied. In temperate regions, lime, applied inquantities of tonnes per ha, but less frequentlythan fertilizers, provides optimum conditions forgrowth of many temperate crop species. Apartfrom neutralizing soil acidity, liming improves theavailability of other nutrients such as phosphate,and lowers the toxicity of aluminium andmanganese. In a long-term experiment in India,with the continuous application of fertilizerswithout lime, yields fell to zero. When the soil pHwas kept near to the optimum, the systembecame sustainable.

In the humid tropics, the lime requirementsare high and the effect may not last long due toleaching losses. However, increases in crop yieldscan sometimes be achieved with minimalapplications of lime due to alleviation ofaluminium toxicity and/or calcium deficiency andcare must be taken to avoid over-liming(R.J. Haynes and R. Naidu, 1998). In manydeveloping countries agricultural lime is notavailable at an economic cost. A possible solutionlies in the development of cultivars which aretolerant of the direct and indirect effects of soilacidity.


5.4. Erosion

Soil erosion is a world-wide phenomenon, but ismore serious in some regions than in others. Inregions where a dry season alternates with aseason with torrential rains soil erosion can bevery severe. At the end of the dry season the soilis likely to have sparse vegetative cover,particularly if the land has been over-grazed bylivestock. Under semi-arid conditions winderosion and desertification are serious problems.

A fertile soil supporting a swiftly growing cropis much less erosion prone than a poor soilsupporting a poor crop. The better developed thesurface canopy the greater the protection againstwind and water action. Because of their vigorousroot systems and large residues, high yielding

crops help to anchor the soil. The roots andresidues returned to the soil enhance productivityby building up organic matter, by improvingaeration and by increasing water infiltration rates.The residual effects of the greater organic matterproduction are significant also in improving soilaggregation.

Land use management appropriate to thetopography and rainfall, together with theappropriate use of fertilizers, can make animportant contribution to soil conservation.

Reduced tillage cultivation practicessignificantly reduce erosion; the proportion ofcrop land subject to no-till techniques isexpanding rapidly in the USA and certain othercountries, for example in Brazil.


6. Toxic substances

to several thousand p.p.m. The use in themanufacture of phosphate fertilizers of phosphaterock with a low cadmium content is one solution,but the total supply is limited. This places theemphasis on developing effective and viablecadmium removal processes and research withthis objective continues.

Ultimately the solution could be acombination of the removal of Cd in themanufacturing process and farm managementstrategies which minimize its potential entranceinto the food chain. The uptake of Cd by plantscan in fact be affected by many factors, such assoil pH, moisture content, variety etc., which canbe controlled by the farmer.

There is no immediate urgency because, apartfrom a few sites heavily polluted by industry, soilcadmium levels are generally well below criticallevels. However, the existence of a medium andlong-term problem is recognized by the fertilizerindustry and studies and research on the subjectcontinue.

Phosphate fertilizers often contain small amountsof elements which occur naturally in phosphaterock and are carried through, in themanufacturing process, to the finished product.When the final product is a relatively high-valuematerial destined for use, for example, in the foodindustry the potentially harmful elements areremoved, but to date economic processes forremoving these elements economically infertilizer production have not been found. Amongthese elements, most attention has been paid tocadmium (Cd).

There is evidence that Cd is slowly buildingup in some soils. This is of concern because Cd isnot essential to plants or animals, and at highlevels can be toxic. Sources include atmosphericdeposition from industrial processes, sewagesludges, animal manures and phosphatefertilizers. In many European countries about50% of total Cd input to agricultural soils is fromairborne sources. Sewage sludges containamounts of Cd which can vary from a few p.p.m.


7. Water

protection of waters against pollution caused bynitrates from agricultural sources. This directiverecognized that, whilst the use of nitrogen-containing fertilizers and manure is necessary forEU agriculture, any over-use of fertilizers andmanure constitutes an environmental risk. Itemphasizes that common action is needed tocontrol the problem arising from intensivelivestock production, and that agricultural policymust take greater account of environmentalprotection.

The objectives of the directive are to ensurethat the nitrate concentration in freshwater andgroundwater supplies does not exceed the limit of50 mg NO3 per litre and to control the incidenceof eutrophication. Having set the overall targets,the directive requires individual Member States,within prescribed limits, to draw up their ownplans for meeting them. These plans involve thepreparation of a voluntary Code of GoodAgricultural Practice, the designation of zonesvulnerable to water pollution from nitrogencompounds and the implementation of actionprogrammes designed to prevent pollution withinthose zones. The measures include a maximumlimit for the addition of livestock manure – themain culprit - equivalent to 170 kg nitrogen (N)per hectare. In addition, the periods in which it isacceptable to apply animal manure are defined.

The agricultural techniques for keepingnitrate out of water supplies are known. TheEuropean Fertilizer Manufacturers’ Association(EFMA), for example, has explained thesetechniques in a code of best agricultural practice(EFMA, 1996).

In general, in developed countries, wheremineral nitrogen fertilizer is a major source ofwater pollution it is usually in areas of vegetableproduction or irrigated sandy soil, or where theoptimum rates are exceeded. A distinction must

There is concern that fertilizers are polluting bothsurface waters and water in aquifers, althoughthe direct impact of the application of mineralfertilizers on the nitrate content of waters ispoorly defined.

According to Union des Industries de laFertilisation (UNIFA), 1997, in France, it isestimated that nitrogen fertilizers account for25% of total mineral nitrogen introducedannually into the eco-system, or 2.3 Mt N out of atotal of 9.4 Mt N. Other major inputs are fromnitrogen fixed by leguminous plant (3 Mt N) andanimal wastes (2 Mt N). In a major catchmentarea in France, 42% of the nitrogen in the waterwas of agricultural origin (arable and livestock),49% domestic and 9% industrial. Labeled 15Nexperiments indicate that not more than 5% offertilizer nitrogen is lost to water during thegrowing season, two thirds of it due to incorrectfertilization practices. In general the extent oflosses is not linked directly to recent fertilizerapplications. Of the agricultural losses 50% wasfrom soils which were left bare in winter and33% due to poor cropping practices i.e. losseswhich could be avoided.

7.1. Drinking water

In the mid-1980s the World Health Organization(WHO) recommended a limit of 50 mg of nitrate,NO3, per litre of drinking water. They reviewedthe recommendation in April 1997 andconcluded that, on the basis of the latest scientificevidence, the value of 50 mg per litre should bemaintained.

The European Union (EU) issued a drinkingwater directive in 1975. In 1980 anotherdirective set a level of 50 mg per litre. Then, inDecember 1991, the EU adopted a directive,known as the Nitrates Directive, concerning the


be made between correct nitrogen fertilizationand excessive animal excrement application.

There is generally little danger of the nitratepollution of ground water due to the applicationof fertilizer on rain-fed crops in developingcountries, both because the application rates tendto be well below the optimum. In irrigatedagriculture, water management is an importantissue.

Section 12.1.1. “Nitrates” of this publicationconcerns the human health issue of nitrates.

7.2. Surface waters

The over-enrichment of surface waters leading toan excessive multiplication of algae and otherundesirable aquatic plant species, with variousundesirable consequences, is a phenomenonknown as eutrophication. Whereas phosphatetends to be the limiting nutrient in inland waters,nitrogen tends to be the limiting nutrient incoastal waters.

7.2.1. Coastal waters

In Europe large areas of the North Sea coastlinesand areas of the Mediterranean have sufferedfrom eutrophication due to nitrates. In the USA,nitrates and phosphates are suspected of causingHypoxia, or the “Dead Zone” in the Gulf ofMexico. There is a great deal of controversy as tothe cause, and even if these nutrients prove to bethe cause, they may originate from severaldifferent sources apart from mineral fertilizers.Nutrient-enriched water, especially run-off fromagriculture, is also incriminated in the Pfiesteriaproblem that killed a large number of fish inChekaspeake Bay, USA, in the summer of 1997.It is highly unlikely that mineral fertilizers areprimarily responsible for either of these problems,but the U.S. fertilizer industry is co-operating fullyin the investigations.

7.2.2. Inland waters

Under temperate conditions, in inland freshwater, P is usually the limiting nutrient and verylow concentrations can cause problems of

eutrophication. Surface water can be enrichedwith P from both point (e.g. sewage treatmentworks) and diffuse (e.g. agricultural land) sources.As the amount of P from point sources hasdeclined in recent years, the percentagecontribution from diffuse sources has increased.Although it has been generally accepted thatmost soils fix P strongly, only very small amountsof P have to be lost from soil to maintain theconcentration of P in drainage at levels likely tocause environmental problems.

Phosphate in the soil is rather immobile andthe loss of water-soluble phosphate throughleaching is usually very small (less than 1 kg ofP2O5 per hectare per year). Ignoring cropremoval, the two primary pathways of loss ofphosphorus from the soil are by erosion (windand water) and in run-off. Under Europeanconditions, the excessive surface applications ofanimal manures can result in significant losses inparticulate matter in run-off. Areas whereintensive animal husbandry is practiced mayexperience the addition of excessive amounts ofphosphorus to the soil, usually in the form ofheavy applications of animal waste eg. slurry orfarmyard manure. Under these conditions, soilscan have such a high content of phosphorus thatlosses may increase.

In tropical lakes, there is evidence thatnitrogen can be the limiting nutrient. Phosphateconcentrations in the water are often higher thanin temperate regions while inputs of N fromsurrounding land may be low.

Surface runoff (including soil erosion) fromcropland, pasture and forest, can contribute tophosphate loading of surface waters. Bestmanagement practices are highly effective ineliminating this possibility and, at the same time,allow for the most efficient use of cropfertilization.

7.3. PotashUnlike nitrogen and phosphate, potash has noknown deleterious effect on the quality of naturalwaters (J.K. Syers, 1998).


8. Air

Ammonia can also react in the atmosphere withsulphur oxides to form ammonium sulphate,which precipitates into the soil with rainfall andcauses acidification.

Although most emissions of ammonia arefrom manure or natural sources, experimentsdemonstrate that nitrogen losses to theatmosphere in the form of ammonia following theapplication of urea can amount to 20% or more,under temperate conditions. Losses occur whenthe urea is not incorporated into the soilimmediately after spreading and they areparticularly high on calcareous soils. Theexpanding practice of reduced tillage cultivationis increasingly the surface application of urea.Losses are even higher, up to 40% or more,under tropical conditions, on flooded rice and onperennial crops to which the urea is applied onthe surface, such as bananas, sugar cane, oil palmand rubber.

8.2. Greenhouse gases

Carbon dioxide (CO2), methane (CH4) and nitrousoxide (N2O) are the three most importantgreenhouse gases. They absorb solar radiationrather than allowing the heat to be radiated awayfrom the earth. Their impact as greenhouse gases,or global warming potential (GWP), is a functionof two factors, their “radiative forcing” and ontheir lifetime in the air. Taking the GWP of CO2

as 1, that of CH4 is 21 and that of N20 is 310.

8.2.1. Carbon dioxide

Fixation of carbon dioxide by photosynthesis isthe source of organic carbon in crops andeventually in soils. Crop production practices thatenhance photosynthetic activity improve theretention of carbon. Decomposition of organic

Nitrogen can be lost from agricultural systems inthree forms which may cause pollution; nitrateloss by leaching, ammonia volatilization andnitrous oxide loss during denitrification ornitrification. Ammonia loss to the atmosphere andits subsequent deposition contributes to theeutrophication of natural habitats and marinewaters and to the acidification of soils and lakesas the NH4 is converted to NO3. Losses bydenitrification are harmless if the end product isnitrogen gas but if the resulting gas is nitrousoxide there is a contribution to the greenhouseeffect and to depletion of ozone in the upperatmosphere.

8.1. Ammonia

H. Kirchmann (1998) observed that ammoniadeposition from the atmosphere may enrichterrestrial and aquatic ecosystems. On average inWest Europe 92% of all ammonia originatesfrom agriculture. About 30% of the nitrogenexcreted by farm animals is released to theatmosphere from animal houses, during storage,grazing and application of animal wastes to thesoil. Ammonia emissions from growing arablecrops are low, but emissions can be higher fromdecomposing crops. Composting results in highammonia losses.

Deposition of ammonia takes place over areaswhere lower amounts would have been supplied.This deposition together with that from nitrogenoxides decreases biodiversity, but it can increasecarbon storage in sediments and forest soils. Nearvery large animal farms, local toxic effectsdamaging the surrounding vegetation can occur.

Ammonia deposition contributes toacidification of soils as ammonia is nitrified tonitrate and then nitrate is lost by leaching.


matter releases carbon dioxide back to theatmosphere. Good fertilization and tillagemanagement practices improve the net gain ofcarbon to the soil.

Recent estimates indicate that agricultural andforested land in the Northern Hemisphere is nowa net sink for carbon dioxide from thesoil/plant complex due to increased vegetativegrowth. According to E. Solberg (1998), for everypound of nitrogen applied as fertilizer,10 to 12 pounds of carbon can be sequestered.The rapidly increasing use of reduced tillagesystems is helping to rebuild soil organic matter,hence increasing the quantity of carbon stored.

8.2.2. Nitrous oxide

Nitrous oxide has a greenhouse effect and isconsidered to be detrimental to the ozone layer.According to experts of the IntergovernmentalPanel on Climate Change (IPCC), nitrous oxide isresponsible for 7.5% of the calculated greenhouseeffect caused by human activity. Its concentrationin the atmosphere is increasing at a rate of about0.2% per annum. Soils are the major globalsource of N2O accounting for some 65% of allemissions; they are the result of microbialprocesses. Nitrogen fertilizers can be a direct andindirect source of N2O emissions; IPCC currentlyassume an N2O emission factor of 1.25% offertilizer N applied, but with a nine-fold range,from 0.25% to 2.25%. In general, fertilizermanagement strategies that increase the

efficiency of N uptake by crops are likely toreduce emission of N2O to the atmosphere. Forfurther information, refer to O.C. Bockman andH.-W. Olfs (1998) and K.A. Smith et al. (1997).

8.2.3. Methane (CH4)

Methane production mainly stems from wetlands,paddy fields, gastric fermentation withinruminant animals, animal wastes, domesticsewage and abiotic sources such as coal miningand natural gases etc. The direct impact ofchemical fertilizers on methane emission is notclear.

In the USA it is estimated that agriculturalsources account for 29% of US methaneemissions. Of the agricultural emissions ruminantanimals account for 62%, animal waste for 32%and rice paddies for 5%. There are indicationsthat cultivation and N fertilization decreases therate at which CH4 is taken up from theatmosphere by soils, thus contributing towardsatmospheric methane levels, but the amountsinvolved are small relative to total sources.(W. Griffith and T. Bruulsema, 1997).A. Suzuki (1997) reports that rice paddy fields inJapan are thought to account for about 10% to30% of total methane emissions from all sources.In rice paddies methane is formed by theanaerobic decomposition of organic matter. Theaddition of readily decomposable organic mattersignificantly increases methane emissions.


9. Nutrient losses and efficiency

Data from Rothamsted Experimental Stationin the UK for phosphorus, show that from 1843to until the 1970s, the overall P offtake was abouta third of that applied, similar to Finck’s data. Butwith today’s yield of 8.5 t/ha grain, the P offtakein grain plus straw is almost equal to the annualapplication, of 35 kg P/ha, although notnecessarily from the P applied for that particularcrop. Similarly the increased yield of winterwheat now removes in grain plus straw most ofthe K applied each year (90 kg K/ha).

9.1. Nitrogen

When assessing the efficiency of nitrogen, it isimportant to take account of the fact that theplant is, in fact, in competition with the soilmicrobial population. This is especially so in soilsin which organic matter is accumulating.

Pilbeam (1996) collated data fromexperiments in which 15N labeled fertilizer, withN in different forms, was applied at differentgrowth stages to rain-fed crops of wheat grown indifferent locations worldwide. The proportions ofnitrogen taken up by the crop and soilrespectively varied widely in response todifferences in rainfall and evaporation betweenthe locations but the proportion of appliedlabeled N that was unaccounted for, andpresumably lost from the crop-soil system, waslargely independent of variations in climate. Theunexplained loss of fertilizer N ranged from 10%to 30%, average 20%.

A.E. Johnston (1997) reported that 15Nexperiments at the Rothamsted ExperimentalStation in the U.K. showed that, on average, about20% of the applied N had been incorporated intosoil organic matter between application andharvest.

In view of the large quantities involved,inefficiencies in fertilizer use represent asubstantial economic loss. For example, given thatabout 80 Mt of N were used in world agriculture1996, a 20% loss with a wholesale price of US$0.66 per kg of N in urea, amounts to US$ 10.6billion. Excessive losses of nitrogen andphosphate to waters and of nitrogen to theatmosphere also present an environmental risk.

Plants acquire most of their nutrients eitherfrom soil reserves or from recently addedfertilizers or organic manures. Assessing whetheradded nutrients are used efficiently is usuallydone by the difference method.

where A is the nutrient tested at amount Aa,and Au is the amount of A in the crop grownwith and without A. Calculated in this way therecovery of added nutrients is very dependent onthe yield of the crop receiving the nutrient beingtested, and the amount of nutrient which issupplied by the soil. Different time scales can beused. Usually only one crop or year is consideredbut, for soils in which reserves of plant availablenutrients can be accumulated, it is appropriate toconsider a longer time span.

A. Finck (1992) considered that theproportions of fertilizer nutrients taken up by thecrop during the season of application are asfollows:

• Nitrogen: 50-70%

• Phosphate: 15%

• Potash: 50-60%

% efficiencyAu in crop given Aa - Au in crop without A

Ax 100=

(recovery)


These two factors, the unavoidable and partlyunexplained N loss averaging 20% and theaverage of 20% incorporated into the soil,correspond to Finck’s 50 to 70% estimate ofplant uptake. The nitrogen incorporated into thesoil as organic matter may subsequently bemineralized and become available to subsequentcrops. And because it is not easy to predict boththe amount and time at which this organicnitrogen is mineralized it is difficult to giveaccurate recommendations for fertilizer nitrogenapplications.

Although 50% to 70% of the appliednitrogen can be taken up under the controlledconditions of experimental stations, in practice,losses can be much greater.

R. S. Paroda (1997) stated, in relation to India,that “The nitrogen use efficiency varies from 20 to25% in rice, 21 to 45% in maize, 45 to 50% inwheat. A 1% increase in the recovery rate of Nfertilizer would save 98 Kt N, equivalent to 1 Mtfood-grains. In the case of phosphate, recovery variesfrom 15% to 20%”. In an earlier paper, R.S.Paroda et al. (1994) observed that in the rice-wheat systems of Asia, nitrogen fertilizerefficiency is estimated at around 30 to 40%. Formicronutrients, such as zinc, the efficiencyseldom exceeds 10 to 15%.

The following text is extracted from a paperby Peoples et al. (1995).

“Unfortunately, fertilizer sources are not utilizedefficiently in agricultural systems, and plant uptakeof fertilizer N seldom exceeds 50% of the N applied.One of the principal reasons for the poor efficiency infertilizer use is that a proportion of the N applied (upto 89%) is lost from the plant-soil system. FertilizerN can be lost by leaching, erosion and run-off, or bygaseous emissions. The relative importance of theseprocesses can vary widely, depending on theagricultural system and the environment. Similarlythe relative importance of NH3 volatilization anddenitrification varies considerably and depends onthe agro-ecosystem, form of fertilizer N used, cropmanagement imposed and the prevailingenvironmental conditions. It is puzzling that farmers

in so many countries tolerate the poor efficiencies offertilizer use. They persist with poor agronomy whensimple management practices are available whichcould increase the efficiency of N uptake anddecrease costs of production. Special problems arisewith crops such as rice, cotton and sugar cane whichreceive large applications of N but which also loselarge amounts of N by denitrification and NH3

volatilization. When the economic situation is good,farmers are unconcerned about applying excessamounts of N, but the environmental consequences ofthis wasteful practice certainly need to be considered....Many approaches are now available to control thelosses of fertilizer N by NH3 volatilization anddenitrification”.

In work in China (A. Dobermann, 1998), in25 on-farm experiments, the average plantrecovery of N by an early rice crop averaged29% (range 10% to 65%), compared with 41%in a experimental station trial. In the case offarmers’ practice 5 kg grain per kg of N appliedwas obtained compared with 24 kg on theexperimental station. On a late rice crop, recoveryaveraged 5%, range 0% to 12%. The authorestimates that only 60% of the potential yield isachieved in intensive rice-growing areas of Asia,with very high N losses to the environment.

In trials on rice in Vietnam (A. Dobermann,1998), average recovery efficiency of applied Nwas 40% in farmers’ practice, but with a yield ofonly 11 kg grain per kg N applied. At anothersite, with improved agricultural practices arecovery of 69% was obtained by farmers, and30 kg grain per kg N.

Much can be achieved by improvingmanagement practices. Matson et al. (1998),working on wheat in an intensive agriculturalregion of Mexico, found that an improvedmanagement system reduced gaseous loss of Nfrom about 14 kg N/ha to virtually zero.

A greater plant uptake can also be achievedwith new varieties. A. Suzuki (1997) reportedthat a high yielding variety of rice in Japan tookup about 160 kg N per ha whereas a commonlygrown variety took up 130 kg/ha.


9.2. Phosphate and potash

Until a few years ago, it was believed thatphosphate (and potash) “fixed” by the soil wentover into plant-unavailable, inert and henceuseless forms. There has, however, been a changeof perception in recent years. Experiments haveshown that in many soils reserves of plantavailable P and K can be built up over time. Soilsenriched with these reserves frequently gavelarger yields than soils without the reserves.Hence the plant-uptake figure of 15% for Punderestimates the long-term efficiency ofphosphate fertilizers. Phosphate (and potash)residues accumulated in the soil are notnecessarily lost - but this is not a reason foraccumulating these residues unnecessarily. Thereare critical values of phosphate and potash belowwhich yield decreases appreciably and whichrepresent a financial loss to the farmer. Toaccumulate P and K in the soil above thesecritical levels is an unnecessary cost for thefarmer. It may also pose an environmental risk, inthat soil lost by water or wind erosion to streams,rivers and lakes takes its nutrient load with it(A.E. Johnston, 1997). Further work is required toestablish these critical soil levels under differentconditions. Work to improve the plant uptake ofapplied P and K is also required.

Phosphate has both direct and indirect effects.The increased availability of phosphate has apositive effect on the quantity and quality ofagricultural outputs. Through indirect interactioneffects, phosphate increases the response ofagricultural production to the other inputs suchas nitrogen and potassium and has positive effectson biological nitrogen fixation, soil organic mattermaintenance, water-holding capacity, soil erosioncontrol and other soil physical and chemicalproperties. All of these positive effects result inincreased agricultural output, sustainedproductivity and land conservation(C.A. Baanante, 1998).

9.3. Products

How can these high losses of nitrogen bereduced? In fact, improvements in fertilizer useefficiency can be detected in most agriculturallyadvanced regions, but this can be attributed toimprovements in cultivation practices, techniquesof fertilizer application and crop varieties. Apartfrom some developments in coated, controlledrelease fertilizers and nitrification inhibitors, therehas been little significant change in thefundamental nature of the main fertilizerproducts for many years, or even decades. Thereis little incentive to invest in the research anddevelopment of a bulky, low-priced commoditywhich offers little scope for productdifferentiation.

9.3.1. Slow release fertilizers

Controlled release nitrogen fertilizers haveagronomic advantages, especially in tropicalregions, and in regions with light-textured soilsand under heavy rainfall or irrigation, where Nlosses are particularly large. However, to date thecost of slow-release fertilizers has limited theiruse to high value crops such as vegetables.

The use of controlled release nitrogenfertilizers on field crops is most advanced inJapan, on rice, whose production is heavilysubsidized. The amount of fertilizer required byrice is commonly applied in 3 to 4 applications.This is labour intensive and in order to reducethe number of applications, coated slow-releasefertilizer have been studied. Experimental resultsso far have indicated that a single application ofthe whole amount of coated fertilizers in a basalapplication gives yields comparable to those withtraditional split applications. Also the efficiency ofnitrogen use could be improved by 10% to 20%due mostly to an increase of about 16% in theplant uptake of N.


9.3.2. Nitrification and ureaseinhibitors

Environmental restrictions in certain developedcountries may encourage more farmers to usenitrogen or urease inhibitors in association withnitrogen fertilizers in areas where it is essential toreduce losses for environmental reasons. Theapplication of urea (or a urea/ammonium nitratesolution, UAN) amended with a urease inhibitorwould generally permit a substantial reduction innitrogen losses to the atmosphere, andconsequently also in the application rates, withoutaffecting growth and yield of fertilized crops.

The future, and in particular the wider use ofslow or controlled release fertilizers, andnitrification and urease inhibitors primarilydepends on the development of new, effective,low-price and non-toxic products. Even ifpromising new products were developed, due tolengthy, time-consuming tests and data collectionfor registration purposes, the introduction to themarket would take several years. It should also betaken into account that giving advice to farmerson how to use them correctly would be veryexpensive.

The whole question of controlled releasefertilizers, nitrification and urease inhibitors, isdealt with by in detail by M.E. Trenkel (1998).

9.3.3. Nutrient absorption enhancers

Increasing the absorption of applied nutrients bythe plants, as opposed to the soil, is a means ofincreasing fertilizer use efficiency. J.L. Anders andL.S. Murphy (1997) presented work with apolymer which shows improved nutrient uptakeand nutrient use efficiency.

9.3.4. Bio-fertilizers; microbialinoculants

Microbial seed inoculants, commonly but wronglycalled bio-fertilizers, are able to enhancebiological nitrogen fixation or to solubilize soilphosphate. The inocultants are claimed to be costeffective, eco-friendly and renewable, and

generally capable of supplementing chemicalfertilizers in sustainable agricultural systems.

It has long been known that the inoculation ofefficient strains of the symbiotic Rhizobium can bebeneficial for leguminous pulses and oilseeds.Free-living organisms such as Azobacter andAzospirillum have proved effective for rice andcertain other crops. The problem with inoculantsis that establishment and therefore effectivenessdepend on the natural conditions and on the skillof the user. As regards the product itself, theinoculant is a living material and there areproblems due to the need to select the mosteffective strains, the difficulty of quality control,the short shelf-life, the need to avoid hightemperatures in storage etc.

As regards phosphate, several phosphate-solubilizing bacteria are known to mobilizesignificant quantities of soil phosphate that wouldotherwise not be available to the plant, but theireffectiveness is variable and not predictable.Vesicular-arbuscular mycorrhizae havefavourable effects on P uptake but much moreresearch and development is required beforereliable commercial products can be madeavailable. At present it is difficult to producemycorrhizae in bulk.

The Food and Fertilizer Technology Centerfor the Asia and Pacific Region (FFTC, 1997)report that, while there is an increasing interest inAsia in the use of N-fixing and P-solubilizingbacteria, the technology of producing and usingthem is still at an early stage. While some arevery effective, farmers often find themselvespaying large sums for useless products. There is avery large number of different microorganisms inmicrobial products and they are often notidentified, whereas some are crop-specific. Theytend to be heavily promoted and there is a greatneed for standards and for simple and accurateways of measuring their effectiveness.

In general, microbial inoculants have receivedonly limited acceptance by farmers in developingcountries. They show considerable promise butmore development is required. In general, it


seems likely that, in due course, they will becomesignificant supplements to mineral fertilizers butthey cannot replace them.

A considerable amount of work has beendone on microbial inoculants in India. In 1996there were 62 manufacturing units in thecountry. The Fertiliser Association of India hasproduced a booklet on the subject (FAI, 1994).

9.4. The efficient use offertilizers

Efficient fertilization is important from both aneconomic and an environmental point of view. Itis synonymous with minimizing nutrient losses tothe environment, while optimizing crop yields.Excess nitrogen not taken up by the crop is likelyto be lost to the environment. The quantities andrelative proportions of the different nutrientsrequired by particular crop and soil conditionsmust be respected. The challenge is to maintainthe fertility of soils despite the increasingdemands placed on them.

Fertilizer use efficiency has in fact beenimproving in the developed countries. In theUSA, for example, between 1985 and 1995, cornproduction per kg of nitrogen applied increasedfrom 18 kg in 1985 to 22 kg in 1995. Thesituation is much the same with phosphate andpotash. There has been a similar improvement inWest Europe, where agricultural production hascontinued to increase despite reduced fertilizeruse.

9.5. Fertigation

A technique which enables growers to maximizethe use of water resources and to increase theefficiency of fertilizer use is “fertigation”. Thistechnique is particularly appropriate for highvalue crops under arid and semi-arid conditions;it is widely used in Israel. It involves the additionof soluble fertilizers into irrigation systems,preferably using a “drip system” which allows

uniform water distribution and feeding of thecrop. The fertilizer can be applied to the cropwhenever it is needed. The initial investment costmay be expensive, but all irrigation systems areexpensive. Maintenance of the system and itsmanagement requires skilled labour.

9.6. Balanced fertilization

If any plant nutrient, whether a major nutrient ora micro-nutrient, is deficient crop growth is likelyto be affected. One definition of balancedfertilization is “the nutrient mix which gives theoptimum economic return”. This may be at highlevels in intensive agriculture, or at comparativelylow levels in less favourable circumstances. Ineither case balanced fertilization is necessary foruse efficiency.

The application of nitrogen fertilizers tends tobe preferred by farmers, because of theirrelatively low cost per unit of nutrient, theirwidespread availability, and the quick andevident response of the plant. However, theincreased yields deplete the soils of the otherplant nutrients removed by the harvested crops,unless they are replenished.

Research at IRRI in the Philippines has shownthat while the application of an adequate quantityof N increased the yield of rice paddy 2.9 times,it also resulted in the removal of 2.6 times moreP, 3.7 times more K and 4.6 times more S fromthe soil, compared to the amounts removed fromunfertilized soil. In due course, these nutrientshave to be replaced if the yields are not to suffer.The same applies to micronutrients.

In a 1995 FAO document “Rice and theenvironment: production impact, economic costs andpolicy implications” it is stated that incorrectfertilizer use in much of Asia, unbalanced infavour of nitrogen, results in lodging, greaterweed competition and pest attacks, with afinancial loss varying from 4% to 30% of the riceprice.


"Fertilizer use has been increasing rapidly inPakistan over many years but there is a stagnation ofcrop production. This seems to be due largely to theincorrect use of fertilizers. Farmers have beenapplying high amounts of nitrogen, but only smallquantities of phosphate. Other fertilizers, such aspotash and micronutrients are hardly used at all.Organic sources are not being properly integratedwith mineral fertilizers. Under such conditions, thesoil is depleted and it takes more nitrogen everyseason to obtain the same crop”. (FertilizerRecommendations in Pakistan, NFDC, 1997,page 1.)

9.7. Site specific fertilizerapplication

The need for rational and sustainable land use,especially in regions subject to severe populationpressures, emphasizes the need for effective landuse planning. The classification of land typesaccording to their agricultural suitability, togetherwith the implementation of soil conservationmeasures, was used with great success to combatthe erosion and desertification problemsencountered in US agriculture in the 1930s.

Fertilizer recommendations should take intoconsideration specific agro-climatic andenvironmental conditions. Generalrecommendations need to be adjusted to the

conditions of the particular field. They depend onfactors such as soil characteristics, cultivationpractices, quality and quantity of irrigation water,ground water table, crop rotations and themanagerial capacity of the farmer. The expectedyield level of a crop is an importantconsideration.

The rapid progress in information technologyduring the past decade, including GeographicInformation Systems (GIS) and computerizedmapping, offers the possibility of agro-ecologicalzoning which can help in a preliminary selectionof crops and technologies, including appropriatefertilizer use, suited to the local conditions andthe problems encountered.

In highly developed systems, precisionfarming may use satellite communication anddetailed field and crop information to improvefarm operations and nutrient efficiency by meansof the site-specific application of fertilizers. Soilanalysis and crop deficiency diagnosis to facilitatethe fine-tuning of fertilizer rates to actual croprequirements are of fundamental importance toprecision agriculture.

Precision agriculture does not, of course,necessarily require sophisticated machinery andsatellite-positioning systems. Farmers indeveloping countries could well improve theprecision of their plant nutrient programmesgiven soil testing facilities and sound advice.


10. Integrated systems

l’environnement” is gaining widespread support.

“Integrated farming” takes systematic andsimultaneous account of the environmentalaspects, the quality of the produce and theprofitability of the farm. Its aim is to develop anagriculture which is sustainable but whichcorresponds to the farmers’ needs and to society’sexpectations. Soil and water resources andbiodiversity are respected. Fertilization and cropprotection techniques which minimize adverseenvironmental impacts are adopted. Animalhealth and well-being, management of effluentsand waste, optimal use of water resources anderosion control are all taken into account.“Alternative farming” has ideological undertoneswhereas “integrated farming” aims to makeoptimum use of the best known techniques.

A. Leake (1999), of the CWS Farms Group inthe UK, has stated “Integrated farming is a recentdevelopment but is already showing promise in itsability to deliver high yielding crops, cost effectivelywith reduced environmental impact. Such a systemoffers a real alternative for European agriculturecompared to conventional high input systems andorganic low output farming”.

10.2. Land planning

There are examples in certain regions of the EUand elsewhere, particularly in water catchmentareas, of successful co-operation between farmers,water authorities and agricultural advisoryservices which have enabled local environmentaltargets to be achieved. “Landcare” in Australia isan example of a successful land managementprogramme. There are comparable programmesin certain other countries, such as Brazil, India,South Africa....

R.N. Prasad. (1997) stated “The ultimate goals orthe ends of sustainable agriculture are to developfarming systems that are productive and profitable,conserve the natural resource base, protect theenvironment and enhance health and safety in thelong run. Traditional agricultural systems that metthe test of sustainability in the past have not beenable to respond adequately to today’s growth indemand for agricultural commodities required by thecurrent population pressures of humankind andanimals and rapidly declining resources of goodquality arable land and water resources.

The basic principles of soil management forsustainable agricultural systems are:

• Replenish nutrients removed

• Maintain the physical condition

• No build-up of weeds, pests and diseases

• No increase in soil acidity or toxic elements

• Soil erosion must be controlled to be equal or lessthan the rate of soil genesis”.

10.1. Integrated farming

“Integrated farming” or in French “Agricultureraisonnée” is the combination of farmingpractices - including the use of rotations,cultivation, choice of variety and skillful, preciseuse of fertilizers and crop protection products -with measures to preserve and protect theenvironment. The best combination must bespecific to each farm.

The concept is based on the German model(FIP) founded in 1987. In the UK LEAF (LinkingEnvironment and Farming) has support from thegovernment, farming groups, researchorganizations, the fertilizer industry,environmental campaign groups and consumerorganizations. In France, FARRE, the “Forum del’agriculture raisonnée respectueuse de


10.3. Ferti-Mieux

In France, in 1980, the French governmentestablished COMIFER, the “Comité françaisd’étude et de développement de la fertilisationraisonnée”, whose objective is to promote rationalfertilization “fertilisation raisonnée”, making useof all scientific, technical and practical means. It iscomposed of representatives of public authoritiesand educational establishments, farmers’organizations, fertilizer producers anddistributors.

“Ferti-Mieux” defines the steps to be taken inorder to obtain, in a given catchment area, aprogressive change in agricultural practices whichwould minimize the risk of polluting water.Participation is voluntary. It is based on aconsensus, on a national basis, between theMinistry of Agriculture, the farmers’ associations,the fertilizer associations, other Ministries etc.,and at the local level, between farmers, advisors,consumers, water agencies etc.

An approved Ferti-Mieux operation, whichrespects the guidelines, is recognized by a label,which is attributed, for one or two years, by threedifferent national bodies. The label provides aguarantee, for farmers, advisors, financial bodiesand the general public.

10.4. Integrated plantnutrition systems, IPNS

In 1996 IFA published a document prepared byR. Dudal entitled “Plant Nutrients for FoodSecurity”, drawing attention to the importance ofthe effective management of plant nutrients as amajor component of agricultural development. Asubstantial part of the document is concernedwith integrated plant nutrition systems (IPNS) andrelated subjects. He defined Integrated PlantNutrition as “an approach which adapts plantnutrition to a specific farming system and particularyield targets, the physical resource base, the availableplant nutrient sources and the socio-economicbackground”.

The sources of plant nutrients may be mineralfertilizers and/or biological nitrogen fixation and/or organic materials, depending on thecircumstances.

Recommendations of an FAO-IFFCO (IndianFarmers Fertiliser Cooperative) InternationalSeminar on IPNS for Sustainable Developmentheld in New Delhi, India, in November 1997were as follows:

• The development of IPNS requires animproved service to the farmers, in the formof technical advice, inputs, credit, marketingfacilities, public investment in agriculture.

IPNS should:

• address both increased productivity andincreased profitability for farmers, with specialattention paid to the alleviation of poverty inrural areas,

• integrate the maintenance of naturalresources and rehabilitation of these resourceswhere needed and the enhancement ofproductivity in agriculture,

• be system-oriented and should in particulartake account of the interactions between plantnutrient supply and water supply, betweenplant nutrient supply and the control of pestsand diseases,

• improve the availability of energy for the ruralpopulation, in order to save fuel wood andorganic materials used as an energy source,

• be science based, associating agronomy,ecology and social science,

• use a “Farming Systems” approach, notlimited only to cropping systems.

10.5. Leguminous plants as asource of N

Leguminous crops provide a substantial input ofnitrogen into the eco-system. It has beenestimated that biological nitrogen fixationsupplies about 30 to 40 Mt nitrogen per year,which compares with about 80 Mt from fertilizer


nitrogen. The contribution of leguminous plantsto crop nutrition has long been known and madeuse of in traditional systems.

Leguminous crops have a high requirement ofphosphorus and potassium and this has to besupplied. The micro-organisms, living insymbiosis, receive their energy from the plant inreturn for the nitrogen they produce. They arenot efficient converters and the energy used inthe natural fixation process is at the expense ofthe yield of the crop i.e. yields of leguminouscrops tend to be low.

The possibility of using leguminous crops as asource of nitrogen is of particular interest tosmall-scale farmers who cannot afford topurchase nitrogen fertilizers. They are not,however, cost-free. If the production of theleguminous crop is not otherwise economic, theyoccupy land which might be put to better use.M.E. Summer (1998) draws attention to trials inAfrica in which a rotation comprising two orthree years of Sesbania fallow followed by maizegave a spectacular increase in maize productioncompared with unfertilized, continuous maize.However, he points out that it is still necessary toapply phosphate. Furthermore, the maizeproduction was less than half of what could beachieved with a modest nitrogen fertilizer input.

Nor is nitrogen derived from leguminouscrops more environmentally friendly than thatprovided by mineral fertilizers; in fact it is likelyto be less friendly. The amount, rate and timingof nutrient release is difficult to control. In trialson grass/clover leys in the UK (Johnston et al.1994), following the ploughing of the leys, winterwheat was grown and soils were sampled during

the winter and spring. It was calculated thatbetween 110 and 250 kg N per ha were leachedas the ley length increased from 1 to 6 years. Inthe average, through drainage on this soil, theamount of N raised the nitrate concentration inthe drainage from just below 200 mg/l to 400mg/l, eight times the EU limit for nitrate indrinking water.

Green manures, particularly of nitrogen-fixingleguminous plants, are an important source ofnitrogen. However, they can be unattractive fromthe farmer’s point of view if they do not producea salable or comestible product. Farmers withonly a small area of land can scarcely afford touse part of it unproductively. Green manures arelabor intensive. They provide significant amountsof nitrogen but require the application ofphosphate and other nutrients. They are no moreenvironmentally friendly than mineral fertilizers;for example, there is evidence that nitrous oxideis emitted from fields after legumes in amountssimilar to those from fertilized crops. The releaseof the nitrogen fixed by leguminous crops isdifficult to control.

Azolla, a floating aquatic fern associated withnitrogen-fixing blue-green algae is used as asource of nitrogen for flooded rice (FAI, 1994).Used as a green manure the optimum applicationamounts to several tonnes per hectare. The fernrequires a considerable quantity of water and ofphosphate and it cannot withstand hightemperatures. Green manures, such as Sesbaniahave long been used in China (see the report of astudy tour in China, FAO, 1977) but since thedate of that tour the use of nitrogen fertilizersthere has increased from 8 to 23 Mt N.


11. Nutrient accounting

Accounting systems based on the nutrientinput and output are used in some Europeancountries as a measure for the environmentalperformance of farms, particularly in countrieswith a manure disposal problem.

In Denmark, since 1994, farmers have had toprepare fertilization plans and the amount ofnitrogen that may be applied to each type of cropis regulated. Another requirement is that 65% ofthe cultivated area must be covered by a greencrop in winter. There are heavy fines in the eventof infringement. In Germany a federal“Regulation of fertilizer use” model regulationcame into effect in January 1996. The modelmust now be implemented in the individualFederal States. In Norway fertilizer plans are nowcompulsory. In the Netherlands a compulsorynutrient accounting scheme is starting in 1998.Nutrient applications over the maximum will betaxed. See O.L.H. Möller-Hansen et al. (1999)

Nutrient accounts may indicate a deficit aswell as a surplus. The exercise would thereforebe useful also in developing countries where soilsare being mined of their nutrients. A substantialproportion of the nutrients which find their wayinto the manure produced by intensive livestockunits originate from animal feed which has beenimported from other regions of the world, thusdepleting the nutrients in the soils of theexporting regions. But in many developingcountries soils are also being exhausted just toprovide a subsistence for their cultivators.

Using comparisons of nutrient inputs and outputsas a yardstick for environmental correctness offertilizing practices in scientific publications andstudies started during the 1980s. Different typesof nutrient balances came into use. The mostcommon is a comparison of nutrient inputs andoutputs at farm gate level (the alternative “soilsurface balance” is more complicated). Theaccount examines the relationship betweenapplied nutrients and nutrients removal in theharvested crop. It considers all nutrients, whetherof mineral or organic origin, which may beapplied. The system ideally should also considerchanges in soil nutrient levels and, in some cases,admissible losses.

Nutrient accounting is being developed by theOECD as one of the environmental indicators.These are national indicators K. Parris and L.Reille (1999) require careful interpretation. Forexample, a country may have a national surpluswhile experiencing nitrate pollution in some areasand nutrient depletion in others. The nutrientbalance indicator needs to be used in conjunctionwith indicators on farm nutrient management,soil quality and water quality.

Livestock wastes contain substantial amountsof plant nutrients (see the section on OrganicMaterials). It is therefore evident that all sourcesof nutrients should be into account whendetermining rates of mineral fertilization.


12. Health

susceptible to nitrite under acid conditions.(T.M. Addiscott, 1996 and M. Golden andC. Leifert, 1997, C. Leifert et al. 1999).

Phosphate and potash have no known adverseeffect on human health. Both elements are animportant constituent of living organisms. Farfrom potash intake having any harmful effect, itmay have a beneficial effect on human health inreducing hypertension.

12.1.2. Product quality

Some claim that crops grown with “artificialfertilizers” have less taste and are less healthythan, for example, organically grown produce. Infact, the plant does not distinguish between theoriginal source, mineral or organic, of its nutrients- they are all taken up in the same chemical form.

However, according to a literature review byK. Woese et al. (1995), conventionally producedor fertilized vegetables may have a higher nitratecontent compared with organically produced orunfertilized vegetables, especially those green androot vegetables which are nitrophilic. Vegetablesof organic origin also tend to have a highercontent of dry matter. Regarding all otherparameters which determine nutritional valuesand sensory assessment, they noted thatdifferences between the two systems were notsignificant or that the results were contradictoryso that conclusions could not be drawn.

Over-fertilization should evidently be avoidedbut correct fertilization can have a positive impacton the quality of agricultural produce. Forexample, the mineral, protein and vitamincontents of crops may be improved if judiciousfertilization corrects a previously existinginadequate level of nutrient availability. Thebaking quality of wheat, the brewing quality ofbarley and the colour, crispness and texturalcharacter of various vegetable crops benefit from

12.1. Human health

12.1.1. Nitrates

Normally drinking water provides from 10 to30% of the nitrate ingested, the remaindercoming from vegetables, fruit and meat. Theproportion of nitrate converted to nitrite alsovaries widely, but about 7% is typical.

Nitrate in drinking water is considered to be apublic health problem because nitrate rapidlyreduces to nitrite in the body. The nitrite oxidizesthe blood haemoglobin which is unable totransport oxygen to the tissues; this can manifestitself in babies up to six months old, causing theblue-baby syndrome. It is normally due to theconversion by microbes of nitrates into nitrites inthe feeding bottles as a result of defectivehygiene. The occurrence of the syndrome is nowrare, although, for some reason, cases still occurin Hungary and Romania.

Another concern is that nitrite may react withcompounds in the stomach to produceN-nitroso compounds, particularly nitrosamines,which have tested positive in animalcarcinogenicity experiments. Ingested nitrate isabsorbed rather quickly from the uppergastrointestinal tract and most is subsequentlyeliminated in the urine. About 25% of the nitratein blood is secreted by salivary glands, and themicrobial flora of the oral cavity reduce some ofit to nitrite.

It is never possible to prove zero risk, but itshould be taken into account that doses ofnitrosamines which have proved carcinogenic inanimals far exceed those to which humans areexposed. No link to cancer in humans has beendemonstrated.

In fact, there is now evidence that somenitrate is beneficial. Many pathogens are


appropriate fertilization, as can the calibre, tasteand flavour of fruits. Potassium improves thetuber quality of potatoes and the sugar content ofsugarcane. Sulphur increases the protein contentin grain and the oil content of oil-seed crops. Andso on.

12.2. Plant health

Fertilizer use at excessive rates hasdeleterious effects on crop growth. Examples arethe lodging of cereals and the low sugar contentof sugar beet resulting from excess quantities ofnitrogen, nutritional disorders involving traceelements such as zinc due to excessive phosphatefertilizer and lime; impeded seed germinationand seedling injury from too much solublefertilizer salt adjacent to the seed row; theacidifying action of nitrogen fertilizer on soil, andincreased incidence of plant and pest attacks withexcessive nitrogen fertilizer. If the nitrogenapplication leads to acidification of the soil, it caninduce aluminum and manganese toxicity ifcompensating lime is not applied.

As regards crop diseases, the most importantimpact of nitrogen is on vigour and plant growth.These two factors have an important impact onplant susceptibility to many diseases. Vigorousplants with rapid growth are generally moresensitive to obligate parasites and somepathogens are specifically more aggressivetowards vigorous plants. However, most of thenecrotic pathogens attack less vigorous plantswith nitrogen deficiency. Balanced fertilizationprovides excellent protection. The time of

application of fertilizers is important. A wrongtiming may induce substantial growth of foliarparts of plants and maintain high humidityconditions in the crop canopy which arefavorable to disease development.

Phosphorus application seems to favour plantprotection against diseases, either by correcting adeficiency in soil phosphorus, and therebyinducing a better growth of the plant, or byspeeding up the maturation process, disfavoringsome pathogens like downy mildew that effectsthe young tissues.

Potash can increase the efficiency of use ofother nutrients by plants, particularly of N. Potashhas a beneficial effect on the quality of a widerange of crops, especially in terms of improvedprotein quantity and quality. Potash can decreasethe incidence of plant diseases and reduce abioticstresses, particularly cold stress. The element mayhave a direct action on pathogen penetration,lesion size and on inoculum density. An indirecteffect of potassium on disease development is tostimulate the healing process (interaction with thescar parasites), to increase the resistance to cold,and also to delay the maturity and senescence offruits. There is no known pollution or healthhazard due to the use of potash fertilizers inagriculture. However, the application ofpotassium chloride to chloride-sensitive cropsshould be avoided, as should its use on certainsaline soils.

Calcium may have an effect on the cell wall ofplants by making them more resistant topathogen penetration. A deficiency in calciumincreases the sensitivity of plants to many fungi.


13. Biodiversity

Over-grazing is one of the major causes of soilerosion and the grazing livestock population istending to increase. The increased production offodder, with appropriate fertilization practices, isan excellent means of reducing the pressure oflivestock on grazing land.

An indiscriminate reduction in fertilizer usewould require farmers to use more crop acres tomaintain, or increase, present production levels.This would require the use of less productive,more fragile soils.

Urbanization increases carbon emissions,whereas plants absorb carbon. Mannion (1997)noted, however, that, with intensification, theagricultural area is tending to decrease in muchof the developed world, with correspondingincreases for example in the forested area. Thisrepresents a net increase in the carbon sink. Butin the developing world, the agricultural area istending to increase, tropical forest is beingtransformed into agricultural land, andagricultural land is being lost to urbanization.This development clearly reduces the vegetativecarbon sink, as well as resulting in a loss ofbiodiversity and genetic resources.

Currently progress is being made in manyregions of the world in implementing diversity-friendly agricultural practices in soil conservation,withdrawing production from marginal areas,mastering chemical and nutrient runoff, breedingcrop varieties which are genetically resistant todiseases, pests and abiotic stresses.

In the USA, the 1996 Farm Act created newprograms such as the Environmental QualityIncentives Program, the Wildlife HabitatIncentives Program and the Farmland ProtectionProgram. A number of other policy optionsintended to promote sustainability are in variousstages of adoption. In 1996 the Agri-

Plant and animal communities may be directlyaffected by changes in their environment throughvariations in the quality of water, air and soil andsediments and through disturbance by noise,extraneous light and changes in vegetation cover.Such changes may directly affect the biosphere,for example habitat, food and nutrient supplies,breeding areas, migration routes, vulnerability topredators, or changes in herbivore grazingpatterns, which may then have a secondary effecton predators. Soil disturbance and removal ofvegetation and secondary effects such as erosionand siltation directly affect communities, and alsolead to indirect effects by upsetting nutrientbalances and microbial activity in the soil.

A common long-term effect is loss of habitat,which affects both faunal and floral communities,and induces changes in species composition andprimary production cycles. For example, in somecountries, population pressure is leading to thecultivation of unsuitable, fragile soils. Tropicalforests, growing on soils that are usually highlyweathered, are being felled on this account. Alarge proportion of the Amazon forest, forexample, grows on poor soils, which deterioratefurther and rapidly after deforestation. There isample scope for improving agriculturalproductivity on more suitable land elsewhere inBrazil, thus avoiding the opening of new areas ofthe Amazon forest and even allowing somedegraded areas to revert to natural forest.

In Indonesia, land settlement schemes haveinvolved the felling of rain forest, following whichsoils have deteriorated rapidly. With adequatefertilization and good management practices, ithas been shown that this land can berehabilitated, thus avoiding the necessity ofclearing additional rain forest and preventingfurther soil erosion and degradation.


environmental “Accompanying Measures” of theEU accounted for over 2 billion ECU, or aboutUS$ 1.8 billion.

Until recently, the biology of what happens inthe root zone - the rhizosphere - was relativelyneglected.

M.J. Swift (1998) writes “Soil management hasbeen dominated by what may be termed an‘environmental management’ paradigm. Cropproduction is seen as being regulated by its physico-chemical environment which can be altered andmanaged by physical means and the introduction ofinorganic chemicals to suit the crop’s needs. In recentyears an alternative concept of ‘biologicalmanagement’ has been emerging which focuses on themanipulation of biological populations andprocesses in soil as well as on its physico-chemicalproperties. At no location on the earth’s surface hasit been possible to assess the full biological diversityof the community of soil organisms.....Theconventional approach to agricultural managementseeks to bypass or even inhibit these biologicalregulators and often disrupts or destroys ecosystemstability and resilience. A biologically-drivenapproach provides a broader, ecological concept ofsoil management which is more readily translatedacross scales from plot to ecosystem and landscape.It is not only distinct from the green revolutionphysico-chemical paradigm but also from that oforganic agriculture in that it does not eschew petro-chemically derived inputs but rather focuses on theefficiency of their use. Ecosystem science provides aframework which integrates the functional attributesof biological populations with their physical andchemical environments”.

It is known that the heavy use of nitrogenfertilizer inhibits the activity of symbiotic nitrogenfixing organisms such as Rhizobium species. If thelegume plant is well supplied with nitrogen from

the soil and/or mineral fertilizer, it is a lessefficient nitrogen fixer; many legumes do notnodulate in the presence of a high soil nitratelevel It has also been contended that fertilizeruse, particularly nitrogen application, may inhibitthe soil micro-organisms from mineralizingavailable soil organic matter.

Soil invertebrates (ants, termites, earthworms,spiders, millipedes, centipedes etc.) perform animportant function in the maintenance of soilfertility. Mineral fertilizers have been accused ofhaving an adverse effect on the earth wormpopulation. It is certainly possible to demonstratethe lethal effects of fertilizer salts and anhydrousammonia when applied in contact with a livingworm. But only a small portion of the soil habitatoccupied by worms is in direct contact withapplied fertilizers, and consequently, theproportion of the total population detrimentallyaffected is small. A possible adverse impact onthe earthworm population could result from theacidification of soils through the application ofcertain nitrogen fertilizers not balanced byliming; earthworms are inhibited by soil acidity.However, some researchers have established thatthe greater supply of fresh organic materialobtained through fertilization is of far greatersignificance to the earthworm. Size and numbersof earthworms invariably increase as soils arebrought from a low to high level of fertilitythrough effective fertilization.

The circumstantial evidence of theexperiments in which mineral fertilizers havebeen applied continuously for a very long periodof time, in a fully sustainable system, a prioriindicates that correct fertilization practices do notharm soil flora and fauna essential for cropproduction.


14. Organic materials

cool, temperate climates and that inMediterranean, sub-tropical and tropical climates.

14.1. Temperate and coldclimate zones

Johnston (1997) reports that for many years,based on experiments in the UK, the importanceof soil organic matter was played down. Yields ofcrops were the same on soils given NPKfertilizers and farmyard manure (FYM) providedthe appropriate amount of N fertilizer was given.This was so up to the 1970s, even though theannual application of 35 t/ha FYM had resultedin a two and a half fold difference in soil humuslevels between fertilizer and FYM treated soils.However, recent results suggest that humus doesplay an important part in soil productivity. Toachieve the high yield potential of the newcultivars all factors affecting growth, including theroot environment within the soil, have to beoptimum. There are also strong indications that,in the field, soil with more organic matter had abetter structure and roots found sufficient P foroptimum growth at lower concentration ofavailable P, than on soils with poorer structure.The effect has become evident more recently ashigh yield levels are reached.

Large amounts of organic matter have to beadded to soil to increase appreciably soil organicmatter in the short term. In normal farmingsystems the effects can be small. For example, atRothamsted, alternating three years’ grass leyswith three years’ arable crops increased soilorganic matter by only 10% after 18 year (A.E.Johnston, 1973).

It is traditional, good agricultural practice tomake optimum use of organic materials.Unfortunately, a substantial proportion of the

Organic materials influence plant nutrientavailability by:

• providing plant nutrients; although thenutrient content is very variable and low; lessthan 2% total nutrients in cattle manure,about 1% in slurry,

• providing a source of carbon and energy formicrobial activities,

• controlling net mineralization-immobilizationpatterns,

• increasing soil organic matter, which canimprove the structure, water storage andcation exchange capacity of soils,

• possibly improving the availability of P.

An application of up to 5 t/ha of cattlemanure contains sufficient N to match therequirement of a 2 t crop of maize but cannotmeet the P requirements. The average maizeyield in the USA is about 8 t/ha.

It is also necessary to distinguish betweenorganic material produced on-site, whose onlyaddition to the soil capital is nitrogen fixed bylegumes, and organic material producedelsewhere, which brings in a net addition ofnutrients.

Mineral fertilizers should not be used as asubstitute for manure where manure is available.If there are housed animals on a farm, themanure produced has to be disposed of and thiscan best be done by applying it to the fields. Itshould then be supplemented with fertilizers toarrive at the total nutrient requirement of thecrop. However, globally, the availability ofmanure is far from being sufficient to provide thequantities of plant nutrient required by crops.Manure and fertilizers are complementary, notcompetitive.

In reviewing the topic of organic materials, itis useful to differentiate between the situation in


nitrogen content of manures is lost to theenvironment during storage and handling.Quantities which are effectively applied must betaken into account when making fertilizer plansfor crops.

Manures are bulky and hence expensive totransport and labour-intensive. They are oftenunpleasant, they may contain toxic elements,pathogenic organisms and antibiotics originatingfrom animal feed. Furthermore, it is more difficultto utilize effectively the nutrients, especially thenitrogen, contained in animal manure than thosecontained in mineral fertilizers. The nitrogencontent of manure shows considerable variationover time, between livestock species andaccording to the type and quality of foddersupplied to the animals. The ratio of nutrientsoften does not match that required by eithercrops or grass. The nitrogen (N) in animal manureoccurs in both inorganic and organic forms.Lastly, and perhaps most importantly,mineralization of the organic nitrogen fractiondepends on the temperature and moisturecontent of the soil, cultivation practices, and theoverall organic matter content. It is therefore notpossible to control the release of nitrogen to thecrops. In Europe the contribution of nitrogen toleaching and the input into water is significantlyhigher from animal manure and slurry than fromcorrectly-applied mineral fertilizers.

The initial phosphate and potash content ofmanure and slurry is largely present in thematerial applied to the soil, but there aresubstantial losses of nitrogen. In Europe it isestimated that 37% of the original nitrogencontent of manure and slurry is lost as ammoniabefore it is added to the soil. This comprises 12%lost in winter storage, 7% in summer storage and18% in spreading (EFMA, 1997). It is difficult toobtain accurate estimate of losses during thegrowing season but work at Rothamsted in theUK indicates that they are substantial and muchgreater than losses from applied nitrogen fertilizer(A.E. Johnston, personal communication). Duringwinter the mineral N in FYM treated plots,susceptible to leaching, was much greater than

that in NPK treated plots (D.S. Powlson et al.1989).

There is much evidence that, up to theeconomic optimum rate of application, very littleof the applied fertilizer nitrogen is leached duringthe crop growing season. The applied nitrogen istaken up by the plant and some may be stored inthe soil. The nitrogen in that part of the plantwhich is not harvested, removed or burned, alsogoes into the organic matter of the soil. Some ofthis nitrogen will become available to subsequentcrops but with certain agricultural practices, suchas leaving the soil uncropped out of season, thenitrogen stored in the soil organic matter may bereleased through denitrification, and leached.

14.2. Tropical and subtropicalzones

The soil content of organic matter is oftenrelatively low under warmer climatic conditionsdue to oxidation, and the benefits of increasingthe organic matter content of soils are clearerthan under temperate conditions. Apart from itsplant nutrient content and function in improvingsoil physical properties, there is evidence thatorganic material can help to offset the effects ofsoil acidity and aluminium toxicity, and it maysupply soil sites which hold readily availablephosphate for plant uptake. Trace elementdeficiencies are increasingly common under moreintensive growing conditions and, in the absenceof more precise assessments, organic materialfrom outside sources may incidentally providesome of the needs.

In trials in India, the application of manuretogether with mineral fertilizers has given a clearyield advantage. Long-term experiments showedthat after 20 years of ammonium sulphateapplication, the crop yield declined to zero. NPKplus lime sustained the highest yield and FYMcould maintain stable but lower crop yields.Where combinations of NPK and FYM are giventhe latter could contribute 20% to totalproduction.


In Burkina Faso, fertilizers, manure and amixture were compared over 11 years on anOxisol. All treatments increased maize yieldsduring the first 3 to 4 years. Then during the4-6 year period yields decreased for alltreatments. The mixture gave higher yields thanfertilizers alone over the 11 years. Fertilizerincreased acidity. When soil acidity andexchangeable aluminium were neutralized byliming, the yield increased. Manure helped tolimit the consequences but is incapable ofneutralizing all the acidity induced by thefertilizer.

Speaking about the situation in India,N.E. Borlaug (1996) pointed out that there wasnot enough organic manure available in India tosupply sufficient nutrients to produce the foodgrain needed to feed the population. The supplyof nutrients from organic manure was insufficientto compensate for nutrient depletion and thenutrient supply from this source was unlikely toimprove due to the competing demand foralternative uses such as fuel, fodder and feed.Comparing the situation in China with that ofIndia, he said that one of the reasons for thehigher use of organic matter in China was the factthat the government subsidized coal, thusreducing the need to use organic materials asfuels.

In many African and Asian countries animalwastes and crop residues have competing usesand the problem is one of a shortage rather thana surplus as in Europe and elsewhere. Thesystems produce too little biomass, and much ofwhat is produced, is consumed by grazing

animals and then deposited elsewhere. Thereturn of organic matter to the soil is negligible.

Precautions to avoid the application of toxicsubstances in organic amendments mustevidently be taken. Also the application ofmanure under anaerobic conditions, for examplein rice paddies, should be avoided to prevent therelease of methane. Apart from this, theintegration of mineral and organic fertilization isstrongly recommended.

14.3. Composts

FFTC (1997) reports, concerning the Asia andPacific region, that “there is also an urgent need toreduce pollution from agricultural wastes. Onemeans of dealing with them is to compost them anduse the compost as fertilizer. Very efficientcomposting methods are required for this purpose.Malodorous gases emitted during the treatment oflivestock manure or agro-industrial waste can causeserious air pollution. There are various means ofcontrolling such odours.

There are a number of composting plants.Their products are often of poor quality and alsocontain unknown quantities of chemicalfertilizers, in proportions unsuited to crop needs.There is an urgent need to define standards fororganic fertilizers.

Because of the difficulty of quality control, mostcommercial organic fertilizers are not covered by thetype of national standards which govern the qualityof chemical fertilizers”.


15. Resources

indicated a 12-year supply. 17 years later theUSA still had a reserve:production ratioindicating about 9 years supply.

15.1.2. Phosphate and potash

Phosphate deposits are widespread throughoutthe world but their economic recovery dependson the cost. The most accessible and higherquality rocks tend to be mined first; according toIFA statistics the average P2O5 content of the 125Mt of phosphate rock mined in 1980 was 32.7%,whereas that of the 141 Mt mined in 1996 was29.5%. At the present rate of phosphate rockproduction and with production costs of the sameorder as at present the “reserves” are sufficientfor at least 80 years, and at somewhat highercost for 200 years. The “resources” which couldbe economically mined at higher cost are muchgreater. On most soils almost all the phosphatenot taken up by the crop is retained in the soil. Itis possible that techniques for the recovery of thisphosphate may be developed in due course.Phosphate losses by soil erosion can beminimized by following Codes of GoodAgricultural Practice.

There is no concern about potash resources,the known high quality reserves being sufficient,at present rates of use, for several hundred yearsand resources, recoverable at higher prices for atleast a thousand years. Nevertheless, prudence inthe use of phosphate and potash reserves isadvisable since there are no known replacements.

15.1.3. Land

There is evidently a limit to the area of fertileagricultural land in the world. Even in 1975,according to an FAO survey, 54 countries couldnot feed their populations with traditionalmethods of food production, and the number hasincreased significantly since that date.

15.1. Resource availability

15.1.1. Energy

Fertilizers, especially nitrogen fertilizers, requirefossil fuel energy to manufacture, and some totransport and apply. It is estimated thatworldwide agriculture uses about 5% of globalenergy consumption. This includes nitrogenfertilizer production, which is estimated toaccount for less than 2% of annual world energyconsumption. This estimate of 5% excludes thetransport and processing of the agriculturalproduce which is more energy intensive; for 1 kgof bread, growing the wheat takes about 20% ofthe energy used, while milling, baking anddistribution account for 80%. Thanks tophotosynthesis, in the case of cereals and rootcrops the harvested energy is substantially greaterthan the energy input. In the case of intensivehorticulture the energy input may be higher thanthe energy output.

In France (Commissariat Général du Plan,1997), in 1995 the manufacture of fertilizersaccounted for 1% of total energy consumption.Agriculture, including the application of thesefertilizers, accounted for 1.6%. The foodprocessing industry, conservation and preparationaccounted for a further 8%.

The energy requirements for the manufactureof fertilizers may be met by natural gas, oil,naphtha or coal depending on the cost andavailability in the region of the world where theammonia is produced. In 1995 known coalreserves amounted to about 450 years of 1995production, natural gas 66 years and petroleum43 years. Additional reserves tend to becomeavailable as time passes, due to new discoveriesand/or technical progress. For example, in 1978the US natural gas reserves:production ratio


Furthermore, substantial areas of goodagricultural land are being lost each year due tourbanization and deterioration, the latter due, forexample, to salinity, erosion and desertification. Itis estimated that every year soil erosion and otherforms of land degradation rob the world of 5 to 7million hectares of farming land (FAO, 1995).

Apart from areas of fertile land purposelyidled in the USA and West Europe, there aresome reserves of land which could be cultivated,particularly in Sub-Saharan Africa and SouthAmerica, but three quarters of this land suffersfrom soil and terrain constraints. Much is underforest. The amount of additional fertile, well-watered, non-erodable, unforested land that canbe brought into agricultural production at lowcost is very limited. Somewhat more land couldbe brought into production with significantinvestment in reclamation or irrigation, but therate of increase of irrigation is slowing becausewater is another increasingly scarce resource.

In any case, over the last 50 years, theincrease in agricultural production has beenachieved mainly by increasing crop yields - theoverall agricultural area has expanded relativelylittle. In 1960, the global area under arable andpermanent crops was about 1.4 billion ha. By1990, this had expanded by just 3.5% to 1.48billion ha. But the world’s farmers were able togrow about one billion tons more cereals in 1990compared with 1960. According to FAO, four-fifths of agricultural growth in developingcountries is likely to come from intensification(increased yields, multiple cropping and shorterfallows.

15.1.4. Water

Agricultural irrigation uses over 70% of theworld’s supplies of developed water and in thedrier farming regions crop production is heavilydependent on irrigation practice. Agriculture isfacing increased competition for limited waterresources. During the next three decades, therewill be an increasing number of water-deficitcountries and regions including not only West

Asia and North Africa but also some of the majoragricultural producing regions of the world suchas the Indian Punjab and the central plain ofChina. The efficiency of utilization of irrigationwater is often low and around 50% of theincrease in demand for water could be met byincreasing the effectiveness of irrigation(D. Seckler et al., 1998). It is therefore extremelyimportant to improve the efficiency of water useand it is established that something approachingthe economic maximum of plant material ensureshigh water use efficiency. This objective will beachieved only with a well nourished plant. Otherexperiments have shown that the return fromnitrogen is much increased by irrigation (G.Cooke., 1966, pages 245 -246, J.C. Ignazi., 1992and J.S.P. Yadav et al., 1998). The dependence ofwater use efficiency on plant nutrient supply isreviewed by J.G. Davis, 1994. In fact any inputfactor that increases economic yield will improvewater use efficiency (FAO, 1984).

UNDP’s 1998 Report

UNDP’s 1998 World Human DevelopmentReport emphasizes the fact that it is the poorwhich are hit hardest by environmentaldegradation. Past deterioration of resourcesworsens current poverty. This renders verydifficult the important tasks of the preservationand restoration of agricultural resources,reforestation, prevention of desertification, thefight against erosion and soil nutrientreplenishment. It is a vicious circle. Individualsconfronted with poverty are obliged to over-exploit resources, which risks exhausting them,which in turn increases their poverty. The poorwill be increasingly pushed to live on fragile land;by the end of the next decade it is possible that abillion poor people will have to live on fragileland as against 500 million today.

The problem of land degradation is mostserious in Africa and Asia, with two thirds of theworld’s poor. The problem of land degradation isworse in arid areas. And this is not particular to


developing countries. The continent which hasthe largest area of arid land subject todesertification is North America (74%), justahead of Africa (73%).

Deforestation is another problem. Almost athird of the earth’s forest have disappeared andabout two thirds of those which remain aresubject to serious modifications. Forests retainand regulate water and their destruction can leadto floods and drought.

Today about a third if the world’s populationdepends on renewable resources. By 2025 asubstantial proportion of the population of sub-Saharan Africa and South Asia will dependlargely on these resources, as will a substantialnumber in Latin America and the Caribbean. Thearea of arable land per person is likely to be halfthe present low level of 0.27 ha. By 2050 morethan two billion people will live in regions with aland shortage, due to desertification anddegradation, in particular in South Asia and sub-Saharan Africa.

In the world as a whole, the use of water isincreasing rapidly. By 2025 it will have increasedby 40%. By 2050 the number of peoplesuffering from a water shortage will increase from132 million to between 1 and2.5 billion. Almost two thirds of the world’spopulation will be confronted with a moderate orhigh shortage of water. Some believe that waterwill be an important cause of wars in the 21st

century.

15.2. Recycling

There is, therefore, no immediate problem withthe availability of the raw materials for fertilizersbut waste should evidently be avoided, for botheconomic and environmental reasons, and wherepossible nutrients should be recycled if this canbe done safely.

Animal and human waste, and particularlyanimal wastes, contain substantial amounts ofplant nutrients. Certain industrial wastes containelements which are required as micro-nutrients,

and can be used to manufacture micro-nutrientfertilizers. According to UNDP (1998) if presenttrends continue the production of wastes in theworld will increase five times by 2025,increasing pollution and the health risks whichare associated with pollution especially indeveloping countries.

Recycling human and animal waste inagriculture has a long history. Among the benefitsof the application of organic wastes in agricultureare improvements in soil fertility, the premiumpaid for organic vegetables, and the conversion ofwaste materials into useful resources. The readyavailability of mineral fertilizers is considered bysome as a disincentive to the rational use oforganic wastes.

In West Europe, livestock wastes account for30% of the nitrogen, 48% of the phosphate and63% of the potash available for application tocrops, much of it coming from intensive livestockproduction units. However, whereas some regionshave a large over-supply of livestock wastes, otherregions have an under-supply, and the material isneither easily nor economically transportablefrom one region to another, even within the samecountry. According to EFMA (1997), in WestEurope non-livestock wastes account for only 3%of the nitrogen, 4% of the phosphate and 1% ofthe potash available for agriculture. The EUParliament has recommended that energyproduction from small-scale biogas plants shouldbe promoted as a useful way of disposing ofanimal waste.

In the USA it is estimated that in 1992 oftotal available plant nutrients, animal wastesaccounted for 10% of the nitrogen, 24% of thephosphate and 22% of the potash. However,because of transportation costs use of animalwaste as fertilizer is economically feasible only ifon-farm or nearby sources exist, and thus thewaste from intensive livestock units is normallyapplied on a limited area near the unit.

Manure and slurry have a low plant nutrientcontent compared with mineral fertilizers, theyare expensive to transport and unpleasant to


handle and spread. Losses to ground water andthe atmosphere are substantial. They are veryvariable in quality depending on the species ofanimal, type of feed, storage conditions etc. Alarge proportion of the nitrogen contained inmanures is insoluble initially and only releasedfor crop uptake when the organic matter isbroken down, which can take from a few weeksto several seasons. In consequence it is difficultto assess the amount of nutrient in thesematerials which should be included in thefertilizer programmes. Norsk Hydro, Norway, isdeveloping an anaerobic digestion system foranimal manures in order to convert most of thenitrogen into an available form and provide amore consistent product.

In most developed countries, the disposal ofsuch wastes is increasingly controlled bylegislation. Organic farming aside, it is thedisposal of manure and slurry which is the mainenvironmental issue, rather than of recycling.Evidently, where manure and slurry are applied,it is important to take their nutrient content intoaccount when determining rates of mineralfertilization - until the mid-1980s this was oftennot the case.

Industrial waste is used as a source of micro-nutrients in mineral fertilizers. Only a smallproportion of mineral fertilizers. The beneficialre-use and cycling of industrial wastes, where thiscan be done safely, is normally encouraged by

the authorities but care must evidently be takennot to introduce toxic substances.

The impetus to making better use of waste iscoming mostly from the fact that, in mostindustrialized countries, it is becomingincreasingly difficult and expensive to find landfillsites for solid waste. They represent a danger foragriculture. This was highlighted by a collectionof reports from thirteen European countries foran FAO/ECE meeting (1994), on the pollution ofagriculture from urban and industrial origins. Thecheapest and most convenient means of disposalof these wastes is in agriculture. The otheralternative being incineration, which is moreexpensive. The main problem is in fact to disposeof manures and sewage sludge safely. Because ofthe pollution possibilities, under the EU NitratesDirective, due to the risk of pollution frommanure, the EU Commission effectively requiresMember States to introduce regional limits onstocking density by limiting the addition ofnitrogen from animal manure to 170 kg perhectare per year. In addition, the periods in whichit is acceptable to apply animal manure arestrictly defined.

The disposal of sewage sludge in agriculture,even if free of toxic materials and harmfulpathogens, often poses problems for farmers.Food processors and retailers increasingly havecontracts with farmers, which stipulate thatsewage sludge may not be applied.


16. Land spared

Had the cereal yields of 1961 still prevailed in1992, China would have needed to increase itscultivated cereal area by more than three fold andIndia by about two fold, to equal their 1992harvests. Obviously, such a surplus of agriculturalland was not available.”

Land that Indian, Chinese and U.S. farmersspared as a result of rising cereal yields. Areaused is the land actually harvested; area spared isadditional land that would have been needed if1961 yields had not increased.

Mineral fertilizers and land are substitutable inthe sense that an increase in the use of fertilizerspermits a reduction in the area of land cultivated,and vice-versa. The use of mineral fertilizers hasenvironmental costs but all farming, as most ofman’s activities, has an environmental impact.Overwhelmingly the evidence is that mineralfertilizers are necessary for the welfare ofmankind. There are environmental risks but theyare minor in relation to the benefits.

N.E. Borlaug (1997) stated:

“Take the cases of the United States, India andChina as examples. In 1940, when relatively littleinorganic fertilizer was used, the production of the 17most important food, feed and fiber crops in the USAtotaled 252 million tons from 129 million hectares.Compare these statistics with 1990, when Americanfarmers harvested approximately600 million tons from only 119 Mha - 10 Mha lessthan 50 years before. If the United States attemptedto produce the 1990 harvest with the technology thatprevailed in 1940, it would have required cultivatingan additional 188 million hectares of land of similarquality. This theoretically could have been achievedeither by ploughing up 73% of the nation’spermanent pastures and rangelands, or byconverting 61% of the forest and woodland area tocropland. In actuality, since many of these lands areof much lower productive potential than the land nowin crops, it really would have been necessary toconvert a much larger percentage of the pasture andrangelands or forests and woodlands to cropland.Had this been done, imagine the additional havocfrom wind and water erosion, the obliteration offorests and extinction of wildlife species throughdestruction of their natural habitats, and theenormous reduction of outdoor recreationopportunities. Impressive savings in land use havealso accrued to China and India through theapplication of modern technology to raise yields.

61 65 90 9285807570

61 65 90 9285807570

61 65 90 9285807570

0

25

175

100

75

50

225

150

200

125

Mill

ion

ha

INDIAProduction1961 : 87 million tonnes1992 : 200 million tonnes

Area spared

Area used

Source : Norman E. Borlaug (1997).

CHINAProduction1961 : 109 million tonnes1992 : 404 million tonnes

Area spared

Area used

USAProduction1961 : 164 million tonnes1992 : 353 million tonnes

Area spared

Area used

Mill

ion

haM

illio

n ha

0

50

200

150

100

300

250

0

25

100

75

50

200

150


17. Partners in environmentally sustainablefertilizer use

there an outline of useful roles for each group sothat their contribution adds to a collectivemovement in the direction of sustainabledevelopment.

Coordination within the fertilizer industry isthe role of associations such as IFA, but thefertilizer industry cannot be considered inisolation. It is an important, but not the onlyagricultural input and the purpose of all theinputs is to enhance the production of agriculturalproducts. The market for the latter is subject tothe demand of consumers. Like the fertilizerindustry, therefore, also consumers have aresponsibility to society and to their environment.

At least twelve categories of institutions areinvolved in the establishment of environmentallysustainable fertilizer use:

1. Farmers’ associations.

2. Fertilizer manufacturers and distributors.

3. Fertilizer associations, national andinternational.

4. Other input suppliers and their associations;seeds, plant protection products etc.

5. The agricultural marketing sector, foodprocessors, distributors and retailers.

6. Banks and credit institutions.

7. Educational establishments.

8. National Governments. Ministries ofagriculture and of environment - but otherMinistries such as planning, health and labourhave a regulatory role.

9. Governmental research and advisory servicesare particularly relevant to the fertilizer sector.

10. Inter-governmental and United Nationsorganizations such as the EuropeanCommission, FAO, OECD, UNEP, UNIDO,World Bank.

Ideological disputes on the use of mineralfertilizers should not be allowed to distractattention from the main problem, which is thatthe inefficient use of mineral fertilizersrepresents a waste of resources, a large economicloss and may contribute to significantenvironmental problems. Improvements in theefficiency of fertilizer use are also likely toreduce the environmental impact.

In the developed countries the efficiency offertilizer use is increasing, and should continueto increase, but this is not the case in mostdeveloping countries. The aim must be tooptimize agricultural production per unit offertilizer applied, while applying the requiredquantities of fertilizers to satisfy the world’sagricultural requirements. How could this beachieved?

Fertilizers are now indisputably in the centreof the debate on food, environment and society.Farmers apply the fertilizers in the field.Fertilizer companies also impact on society andthe environment through the manufacturingprocess. In between is the entire supply anddistribution chain, with a multitude oforganizations, institutes, and individuals. There isalso research/development and marketing.What contribution can each of these elementsmake to the global movement towardssustainability that world society is nowattempting?

The fertilizer industry consists of manyinterlocking organizations, manufacturers,distributors, institutes, programmes andassociations, as well as individuals. Eachorganization is to some extent constrained inwhat it can do because part of the supply chainis outside its control. Yet there is no commonview of how synergies can be created, nor is


11. Non-government organizations.

12. Donor organizations - bilateral andmultilateral.

In the case of mineral fertilizers, there aresignificant problems associated with their under-use, over-use and incorrect use. In manycountries there are inadequate research andadvisory activities in place. Neither the privatesector nor the public sector alone can resolvethese problems. Cooperation and participation bythe entire supply chain is needed for sustainabledevelopment.

In some fields, a more global vision is beingadopted. For example, the 1994 inter-governmental conference in Cairo on worldpopulation examined the food-populationequation not in simple rich-poor, north-south,hungry-overfed terms, but as a series of complexrelationships between (1) development tomaintain and enhance living standards (2)reduced population growth and (3) greaterenvironmental protection.

The International Agri-Food Network

Whereas the focus of environmental pressures onthe fertilizer industry in the 1970s and 1980swas essentially localized, with problems such asthose associated with eutrophication of surfacewaters by phosphates and nitrates, and nitrates indrinking water, the new environmental agenda ismore regional and global in nature. For example,

the impact of N20 emissions, not just fromfertilizer production, but also from agriculturalactivities in general, is of increasing concern inthe analysis of greenhouse gases and climatechange. Other issues and factors influencing thedrive towards sustainable agricultural productionconcern the growing significance ofbiotechnological advances in crop production andthe use of waste in modern farming systems.

None of these issues is specific to the fertilizerindustry, neither as causative factors nor inpotential solutions.

As the international community, including theUnited Nations, addresses these global problems,through organizations such as the FAO, the UNCommission on Sustainable Development-UNCSD, the Conventions on Biodiversity andClimate Change, etc., it is increasingly importantfor all agribusiness sectors to coordinate theiractivities to ensure that their role isacknowledged objectively, alongside others suchas environmental NGOs which regard organicagriculture as the only solution to sustainablefood production.

In an effort to integrate fertilizer issues withthose of other industry sectors, such as seeds,crop protection, farmers’ organizations andcooperatives, livestock and food distribution andprocessing, IFA was instrumental in forming theInternational Agri-Food Network, IAFN, aninformal panel of all elements in the food chain.


Selected references

Borlaug N.E. (1997). Our Short Memories, inAgricultural Intensification in sub-Saharan Africa.Proceedings of a Centre for Applied Studies inInternational negotiations, Sasakawa AfricaAssociation, and the Global 2000 Program of theCarter Center, CASIN/SAA/Global 2000, Addis-Ababa, August 1997.

Buol S.W. and Stokes M.L (1997) Soil profilealteration under long-term, high-input agriculture,in Replenishing soil fertility in Africa Soil ScienceSociety of America, Special Publication N° 51, pp.97 to 109, Madison, Wisconsin, USA, 1997,

Colman D. and Young T (1989) Principles ofAgricultural Economics. Cambridge UniversityPress.

Commissariat Général du Plan (1997). Energie2010-2020 310 pp. Paris, France.

Conference of Parties (1996). Decision III/II:Conservation and sustainable use of agriculturalbiological diversity. Third Meeting, Buenos Aires1996

Cooke G.W. (1966) The Control of Soil Fertility.Crosby Lockwood & Son Ltd., London.

Cook P.J. and Sheath D. (1997) World mineralresources and some global environmental issues.Nature & Resources. 33.1. pp. 26 to 33.

Crowther, E.M. (1945) Fertilizers during thewar and after. Pamphlet No. 13. Bath and Westand Southern Counties Society, Bath. 59 pp.

Davis J.G. (1994). Managing plant nutrients foroptimum water use efficiency and waterconservation. Advances in Agronomy S3: 85-120.

Doberman A. (1998). Summary report on1997 results of a project of the International RiceResearch Institute, the Philippines, co-sponsoredwith IFA, IPI and PPI.

Addiscott, T.M. (1996) Fertilizers and nitrateleaching. In Hester, R.E. and Harrison R.M. (eds.)Agricultural Chemicals and the Environment. TheRoyal Society of Chemistry, Cambridge, U.K. pp.1-26

Alexandratos N. ed. (1995). World AgricultureTowards 2010, an FAO Study. John Wiley & Sons.Chichester. pp. 189 to 191

Archer J.R. and Marks M.J. (1997). Control ofnutrient losses to water from agriculture in Europe.The Fertiliser Society, Proceedings N° 405,October 1997

Bannante C.A. (1998) Economic evaluation ofthe use of phosphate fertilizers as a capitalinvestment in Nutrient Management for SustainableCrop Protection in Asia edited by A.E. Johnstonand J.K. Syers. CAB International, Wallingford,UK. 1998

Bockman O.C., Kaarstad O., Lie O.H.,Richards I. (1990) Agriculture and Fertilizers.Norsk Hydro. Oslo.

Bockman O.C. and Olfs H.-W. (1998)Fertilizers, agronomy and N2O Nutrient Cycling inAgroecosystems, 52: 165-170, Kluwer AcademicPublishers, the Netherlands.

Laegreid M., Bockman O.C. and Kaarstad O.(1999) Agriculture, Fertilizers and the Environment.CABI Publishing in association with Norsk HydroASA, Oslo.

Borlaug N.E. (1996) Restoration of soil fertility.Talk organized by the Fertilizer Association ofIndia, New Delhi, February 1996.

Borlaug N.E. (1997) Fertilizers and the greenrevolution: past contributions and future challenges.1997 Journal of the Fertilizer Society of SouthAfrica.


Dudal R. (1996) Plant Nutrients for FoodSecurity. IFA, Paris.

ECETOC Report n° 27, January 1988, Nitrateand Drinking Water.

EFMA (1997) “Nutrient Sources”, a reportprepared by Levington Agriculture Ltd.

EFMA (1997) The Fertilizer Industry of theEuropean Union. The issues of today, the outlook fortomorrow. EFMA. Brussels.

EFMA (1996). Code of Best AgriculturalPractice. EFMA, Brussels.

FAI (1994) Biofertilisers in Indian Agriculture.The Fertiliser Association of India, New Delhi.

FAO (1977) China: recycling of organic wastesin agriculture. FAO Soils Bulletin No. 40. Rome.

FAO (1984) Fertilizer and Plant NutritionGuide. Fertilizer and Plant Nutrition Bulletin 9,FAO, Rome.

FAO (1994) Cherish the Earth. SoilManagement for Sustainable Agriculture andEnvironmental Protection in the Tropics. FAO, Landand Water Division, Rome.

FAO (1996) Plant Nutrition for SustainableAgriculture. The Philippines, Technical ReportAG:PHI/94/O1T FAO, Rome

FAO World Food Summit (1996). FoodProduction and Environmental Impact. Technicalbackground document volume 2. Document 11.FAO, Rome.

FAO (1995) Dimensions of Need; an Atlas ofFood and Agriculture, FAO, Rome.

FFTC (1997) Food and Fertilizer TechnologyCenter for the Asian and Pacific Region. 1996Annual Report. Taipei.

Finck A. (1992) in World Fertilizer UseManual. IFA, Paris.

Golden M. and Leifert C. (1997) ProtectionAgainst Oral and Gastrointestinal Diseases: theImportance of Dietary Nitrate Intake, Oral NitrateReduction and Enterosalivary Nitrate Circulation.

Paper presented at a conference on “ManagingRisks of Nitrates to Humans and theEnvironment”. Royal Society of Chemistry,University of Essex, UK, September 1997.Proceedings being printed.

Granli T. and Bockman O.C. (1995) Nitrousoxide emissions from soils in warm climates.Fertilizer Research 42. pp. 159-163.

Griffith W. and T. Bruulsema (1997) GlobalGreenhouse Gases: Implications for North AmericanAgriculture. Potash & Phosphate Institute.Norcross, USA.

Haynes R.J. and Naidu R. (1998). Influence oflime, fertilizer and manure applications on soilorganic matter content and soil physical conditions:a review. Nutrient Cycling in Agroecosystems51: 123-137.

IFPRI (1997) Pinstrup-Andersen P., Pandya-Lorch R., Rosegrant M.W., The World FoodSituation: Recent Developments, Emerging Issues,and Long-Term Prospects. IFPRI, Washington,December 1997.

IFPRI (1999) Pinstrup M.W. World foodprospects: critical issues for the early twenty-firstcentury. IFPRI, Washington, October 1999.

Ignazi J.C. (1992). Improving nitrogenmanagement in irrigated intensively cultivated areas.The approach in France Expert consultation on theprevention of water pollution by agriculture andrelated activities. Santiago, Chile, October 1992.

Johnston A.E. (1973). The effects of ley andarable cropping systems on the amounts of soilorganic matter in the Rothamsted and Woburn ley-arable experiments. Rothamsted ExperimentalStation, Report for 1972. Part 2. 131-159.

Johnston A.E., McEwan J., Lane P.W., HewittM.V., Poulton P.R. and Yeoman D.P. 1994. Theeffects of one to six year old rye grass-clover leys onsoil nitrogen and on the subsequent yields andfertilizer nitrogen requirements of the arable sequencewinter wheat, potatoes, winter wheat, winter beans(Vicia faba), grain on a sandy loam soil. Journal ofAgricultural Science, Cambridge, 122. 73-86.


Johnston A.E (1995) The Efficient Use of PlantNutrients in Agriculture. IFA, Paris.

Johnston A.E. (1997) Fertilizers andAgriculture: Fifty Years of Developments andChallenges. Fertilizer Society. Proceedingsn° 396. York, 1997.

Kinzig A.P. and Socolow R.H. (1994) HumanImpacts on the Nitrogen Cycle. Physics Today47.11. November 1994.

Kirchmann H. et al., (1998) Ammoniaemissions from agriculture. In Nutrient Cycling inAgroecosystems 51:1-3, Kluwer AcademicPublishers.

MacKenzie G.H. and Taureau J-C. (1997).Recommendations Systems for Nitrogen. TheFertiliser Society, Proceedings N° 403.

Leake A.R. (1999) Agronomy and Services.Presentation of the Focus on Farming PracticeProject, 6e Rencontres internationales del’AFCOME, Angers, France, November 1999.

Leifert C., Fite A., Hong Li, Golden M., MowetA. and Frazer A. (1999) Human health effects ofnitrate. IFA Conference on Managing PlantNutrition, Barcelona, July 1999.

Mannion A.M. (1997) Agriculture and LandTransformation. Part 2. Present Trends andFuture Prospects Outlook on Agriculture 26.3, pp.151 to 158, CAB International, Wallingford, U.K.,(1997).

Matson P.A., Naylor R., Ortiz-Monasterio I.(1998) Integration of Environmental, Agronomic,and Economic Aspects of Fertilizer Management.Science Vol. 280, 3 April 1998 pp. 112-114.

Möller-Hansen O.L.H., Breembrock J.A. andLewis K.A. Nutrient record-keeping and reportingfor legislation, crop assurance and traceabilty.The International Fertilizer Society, UK,Proceedings No. 440.

Nambiar K.K.M. (1994) Soil fertility and cropproductivity under long-term fertilizer use. ICAR,New Delhi.

OECD (1997). Environmental Indicators forAgriculture. OECD, Paris.

Paroda R.S., T. Woodhead T. and R.B. SinghR.B. (ed.) (1994) Sustainability of rice-wheatproduction systems in Asia. RAPA publication1994/11. Science Publishers, Lebanon, USA inarrangement with FAO, Bangkok.

Parris K. and Reille L. (1999) Measuring theenvironmental impacts of agriculture: use andmanagement of nutrients. The InternationalFertiliser Society, UK Proceedings N° 442.

Peoples M.B., Freney J.R. & Mosier A.R.(1995) Minimizing Gaseous Losses of Nitrogen.In Nitrogen Fertilization in the Environment, ed. P.E.Bacon, Marcel Dekker, Inc. New York.

Pilbeam C.J. (1996) Effect of climate on therecovery in crop and soil of 15N labeled fertilizerapplied to wheat. Fertilizer Research 45:209-20.1996.

Powlson D.S., Poulton P.R., Addiscott T.M. andMcCann D. (1989). Leaching of nitrate from soilsreceiving organic or inorganic fertilizerscontinuously for 135 years. In J. AA. Hansen andK. Henriksen (eds.) Nitrogen in organic wastesapplied to soils. Academic Press, London, pp. 334-345.

Prasad R.N. (1997) Integrated nutrientmanagement: Indian Perspective. FAO-IFFCOInternational Seminar on IPNS for SustainableDevelopment, New Delhi, November 1997.

Price R. (1993). A Concise History of France.Cambridge University Press, UK.

Reuler H. van and Prins W.H. (eds.) The role ofplant nutrients for sustainable food crop productionin Sub-Saharan Africa. VKP, Leidschendam, TheNetherlands 1993. 231 pp.

Saunders J.L. and Murphy L.S. (1997).Amisorb nutrient absorption enhancer in cropproduction. IFA Agro-Economics CommitteeConference, Tours, France, June 1997.


Scheid Lopes A. and Guimaraes L.R. (1991)Environmental Preservation and Food Production.ANDA. Sao Paulo.

Schmitz P.M. and Hartmann M. (1994).Agriculture and Chemistry. IFA AnnualConference, Turkey, May 1994.

Seckler D., Amarasinghe U., Molden D., deSilva R. and Barker R. (1998) World WaterDemand and Supply, 1990 to 2025: Scenarios andIssues. International Water Management Institute,Colombo, Sri Lanka.

Smil V. (1997) Global Population and theNitrogen cycle. Scientific American. 277.1. July1997. pp. 58 to 63.

Smil V. (1999) Long-range perspectives ininorganic fertilizers in global agriculture. Travis P.Hignett Memorial Lecture, Florence, Alabama,USA.

Smith K.A., McTaggart I.P. and Tsuruta H.(1997). Emissions of N2O and NO associated withnitrogen fertilization in intensive agriculture, and thepotential for mitigation, Soil Use and Management13, 296-304. CAB International, Wallingford,U.K.

Solberg E. (1998) Alberta Agriculture, Foodand Rural Development, Edmonton, Canada,reported by Devine G. in “Political challenges andopportunities facing the global fertilizer industry inthe 21st Century, IFA Annual conference, Toronto,May 1998.

Subba Rao A. and Sanjay Srivastava (1998).Role of plant nutrients in increasing cropproductivity. Agro-Chemicals News in Brief, April-June 1998. FADINAP, Bangkok.

Summer M.E. (1998) Challenges in restoringthe food balance in developing countries. Journal ofthe Fertilizer Society of South Africa, 1998.

Suzuki A. (1997) Fertilization of rice in Japan.Japan FAO Association. Tokyo 1997.

Swift M.J. (1998). Soil fertility, plant nutritionand soil biology relationships: consolidating aparadigm. Fertbio 98, Federal University ofLavras. Caxambu, Brazil, October 1998.

Syers J.K. (1997) Soil and plant potassium inagriculture. The Fertiliser Society. Proceedings N°411, April 1998. York, U.K.

Theobald O. (1997) Recyclage des élémentsnutritifs issus de déchets et de sous-produits enagriculture. Perspectives et contraintes. IFA Agro-Economics Committee Conference, June 1997,Tours, France.

Trenkel M.E. (1998) Controlled-Release andStabilized Fertilizers in Agriculture, IFA, Paris.

UNDP. World Human Development Report.United Nations Development Programme, NewYork, 1998.

UNEP, Terrestrial Ecosystems Branch (1992)Fertilization. Proceedings of the Regional FADINAPSeminar on Fertilization and the Environment.FADINAP. Bangkok. pp. 265-276.

UNIFA (1997) La fertilisation. 7th Edition.Paris, 1997.

Vitousek P.M. , Aber J., Howarth R.W., LikensG.E., Pamela A., Schindler D.W., Schlesinger W.H.and Tilman G.D. (1997) Human Alteration of theGlobal Nitrogen Cycle: Causes and Consequences.Ecological Applications Vol. 7, August 1997.

Woese K., Lange D., Boesss C. and Bögl K.W.Ökologisch und konventionell erzeugte Lebensmittelim Vergleich. Eine Literaturstudie. Bundesinsitutfür gesundheitlichen Verbraucherschutz undVerterinärmedizin, 4/1995.

World Resources Institute. World Resources1994-1995 Oxford University Press, New York,1994.

Yadav J.S.P., A. Kumar Singh and R. KumarRattan (1998). Water and nutrient management insustainable agriculture. Fertilizer News, December1998. FAI, New Delhi.


IFA - International FertilizerIndustry Association

IFA, the International Fertilizer IndustryAssociation, comprises around 500 membercompanies world-wide, in over 80 countries.The membership includes manufacturers offertilizers, raw material suppliers, regional andnational associations, research institutes, tradersand engineering companies.

IFA collects, compiles and disseminatesinformation on the production and consumptionof fertilizers, and acts as forum for its membersand others to meet and address technical,agronomic, supply and environmental issues.

IFA liaises closely with relevant internationalorganizations such as the World Bank, FAO,UNEP and other UN agencies.

IFA’s mission

• To promote actively the efficient andresponsible use of plant nutrients to maintainand increase agricultural productionworldwide in a sustainable manner.

• To improve the operating environment of thefertilizer industry in the spirit of freeenterprise and fair trade.

• To collect, compile and disseminateinformation, and to provide a discussionforum for its members and others on allaspects of the production, distribution andconsumption of fertilizers, their intermediatesand raw materials.

28, rue Marbeuf75008 Paris, FranceTel: +33 153 930 500Fax: +33 153 930 545 /546 /547E-mail: [email protected]: http:www.fertilizer.org

UNEP - United NationsEnvironment Programme

The Production and Consumption Unit of UNEPDTIE in Paris was established in 1975 to bringindustry, governments and non-governmentalorganizations together to work towardsenvironmentally-sound forms of industrialdevelopment. This is done by:

• Encouraging the incorporation ofenvironmental criteria in industrialdevelopment.

• Formulating and facilitating theimplementation of principles and proceduresto protect the environment.

• Promoting the use of low- and non-wastetechnologies.

• Stimulating the worldwide exchange ofinformation and experience onenvironmentally-sound forms of industrialdevelopment.

This Unit has developed a programme onAwareness and Preparedness for Emergencies atLocal Level (APELL) to prevent and to respondto technological accidents, and a programme topromote worldwide Cleaner Production.

39-43, Quai André Citröen75739 Paris Cedex 15FranceTel: +33 1 4437 1450Fax: +33 1 44 37 1474E-mail: [email protected]: http:www.uneptie.org

About IFA and UNEP

mineral fertilizer use and the environment.pdf

Documents