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Improving food andagricultural production in ThailandAn extensive co-operative project uses isotopes, radiation,and related techniques to study some traditional problems

by Patoom Snitwongse and Carl G. Lamm

In the early 1960s, the IAEA and FAO jointlyinitiated the first in a series of large-scale multi-facetedagricultural field projects using nuclear techniques inagricultural sciences. The first project, in Yugoslavia,served as a model for future ones in India, Brazil,Bangladesh, Republic of Korea, Venezuela, andThailand. All were principally funded by the UnitedNations Development Programme (UNDP); those inIndia and Bangladesh also drew support from theSwedish International Development Authority (SIDA).

The Thailand project — for the time being the last oneof this series — stands among the most extensive andtechnically complex, encompassing some 60 specificorganizational and scientific tasks through field studies,experiments, and other activities. (See accompanyingmap.) Traditional problems of soil fertility, watersupply, and animal health are among those that projectscientists are tackling with the help of nuclear techniquesand methods. Started in January 1986 for a 5-yearperiod, the project carries major objectives centering onthe use of isotopes, radiation, and related technologies inthree particular areas:• Mutation breeding. Scientists are aiming to generatenew genetic sources of disease-resistant varieties ofcrops that are economically important.• Soil science. Aims are to help farmers make the bestuse of fertilizers, biofertilizers, and water, and tomaximize biological nitrogen fixation and the use oflocal rock phosphates as sources of crop nutrients.• Animal science. Project scientists are aiming toimprove livestock productivity on small farms.

Most project funds come from the UNDP, which isproviding about US $1.4 million for expert costs andUS $536 400 for fellowship training and purchases ofspecialized equipment and supplies. Support from theGovernment of Thailand amounts to more than 111 mil-lion Baht.

Mutation breeding

Plant breeders have long used radiation techniquesand chemical agents to induce desirable properties incrops or plants. In Thailand, scientists are searching formore disease-resistant food legumes, fibre crops, cerealgrains, oil crops, and vegetatively propagated crops.Among the tasks, germ plasm and induced mutants arebeing screened for resistance to a number of plantdiseases. Techniques are being strengthened in combina-tion with a FAO/IAEA technical co-operation projectthrough establishment of an in-vitro and mutation breed-ing service at the Thailand Department of Agriculture's

Researchers preparing isotope microplots in studies of rice fertiliza-tion in Thailand.

Mrs Patoom Snitwongse is Head, Nuclear Research in Agriculture,Agricultural Chemistry Division, Department of Agriculture,Bangkok. Dr Lamm is Chief Technical Advisor for theIAEA/UNDP/Thailand project (85/004) and a former Deputy Directorof the Joint FAO/IAEA Division.

IAEA BULLETIN, 4/1987 45

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Project-related field experimentsin Thailand

Depar t of Agriculturet of Land Developmentt of LivestockIniversily

lialongkorn Universityice of Atomic Energy for Peace

i Plant breedingSoil scienceAnimal science

Started in January 1986, the Thailand projecttoday encompasses experiments being carried out at32 field stations in 20 Thai provinces, and veterinarysurveys at small farms in more than 100 villages.Other studies are under way at experimental installa-tions — laboratories, greenhouses, livestock sheds,and fields — at the headquarters of the eight par-ticipating Thai institutions: Department of Agricul-ture; Department of Land Development; Departmentof Livestock; Kasetsart University; Khon Kaen Univer-sity; Chiang Mai University; Chulalongkorn Univer-sity; and the Office of Atomic Energy for Peace(OAEP). Additional technical support is provided bythe IAEA and Food and Agriculture Organization(FAO) through their Joint Division headquartered inVienna, Austria, and its allied Laboratory in Seibers-dorf, Austria, outside Vienna. The project's adminis-trative headquarters are at the Central Services Unit,located at the Thailand Department of Agriculture'sLaboratory of Nuclear Research. Already equipped toundertake analyses and training in isotope measure-ments, particularly nitrogen-15, the unit is nowinstalling a mass spectrometer — the first in Thailand— to expand research capabilities. By co-ordinatingthe project with several related international andbilateral activities in Thailand, other resources andexpertise have also become available.

Division of Plant Pathology and Microbiology. Consist-ing of a greenhouse and a laboratory, this unit will offertraining and services to other institutions.

To foster exchange of scientific information andresearch results, a National Mutation Breeding Work-shop was held during December 1986, attracting over70 scientists. Some promising mutants of crop speciesthat are resistant or tolerant of specific diseases alreadyhave been obtained, and these are being tested in fieldtrials — for example, soybean that is more resistant torust. Mutation induction has started on other cropspecies, such as yardlong bean, cow pea, castor bean,and sugar cane.

Soil science

How efficiently crops use fertilizers, or how toimprove the amount of nutrients they can derive fromthe soil, are some of the important questions beingstudied. Some specific activities are devoted to develop-ment of management practices for better use of artificialand natural fertilizers and water. Toward the end of1987, a national training course was held on soil-water-plant relationship studies. (See accompanying box for anoverview of research on soil-water-plant relationshipsunder the project.)

Scientists are especially studying the fate andefficiency of fertilizer nitrogen in acid-sulphate soils.Different sources labelled with nitrogen-15 are beingused, with emphasis on rice, maize, and vegetablecrops. One important finding was that, in some soils,significant quantities of fertilizer nitrogen were immobi-lized in the soil's top layer (30 centimetre depth), and

One of the laboratories in Thailand's Central Services Facility, whichserves as the project's administrative centre.

46 IAEA BULLETIN, 4/1987

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that the crops could recover from 76-87% of it; nitrogenlosses were between 12-24%. Also being studied is theutilization of Thai rock phosphates on different acid-sulphate soils. Results so far demonstrate their practicaluse for rice in soil with a pH value below 4.

Studies of biological nitrogen fixation usingnitrogen-15, which have been increasingly emphasizedover the years, have now reached a stage where farmerscan apply practical results: Soybean can be grown com-mercially with minimum use of nitrogen fertilizers byselecting proper varieties, using Rhizobium japonicumstrains selected for maximum biological nitrogen fixa-tion, and by applying improved crop managementpractices.

Animal science

Project activities concerned with improving animalproductivity rnsiniy empuasize the application of

immunoassays for determination of progesterone (areproductive hormone) in cattle and buffalo. Work alsoincludes veterinary surveys at small farms and provisionof an analytical quality control service throughChulalongkorn University. Laboratory and field worknow centered there is being transferred to three otheruniversities so that more of the country's livestock canbe reached. Reproductive patterns of dairy cattle andswamp buffalo at small farms and in larger herds arebeing assessed to establish correlations betweenreproductive performance and progesterone tests.

Studies are planned to develop radiation-attenuatedvaccines against parasitic diseases — specifically, theLiver Fluke disease, one of the most important parasiticpests afflicting livestock in Thailand. Epidemiologicalstudies are being intensified of the disease's prevalenceand its effect on productivity and work capacity ofbuffalo and cattle as a prerequisite to a possible vaccina-tion campaign.

Soil, water, and plant productivityby Klaus Reichardt

In Thailand, water and fertilizer economy in fieldcrops is an important issue in improving agriculturalproduction, mainly in the northeastern and eastern areaswhere sandy soils prevail. These soils have low fertilityand an extremely low capacity for holding water, but theyare of great importance for food production. Knowledgeof water regimes, crop water uses, root distributions,water retention characteristics, and fertilizer leaching,under different cropping conditions, will therefore con-tribute toward adoption of more rational managementpractices and, ultimately, improved crop productivity.

The country's Department of Land Development isestablishing several field experiments and pilot projectsusing nuclear technology to assess the water contentand bulk densities of soils, and fertilizer loss by leaching.Results of these trials will immediately be transferred tofarmers through, for example, the Khonkaen Cholburiand Rayon Rainfed Agricultural Pilot Projects, wherefarmers apply concepts of soil and water conservationthrough the guide of professionals from the Departmentof Land Development.

Nuclear tools and techniques can play an importantrole. Suitably calibrated neutron probes can be used tomeasure soil water content at different depths in the soilprofile, and at different time intervals, during the entirecrop cycle. With this information, it is possible to studysoil water storage, fluctuations during the growing sea-son, and to analyse periods of water shortage andexcess at various times in the crop's development.Together with rainfall data, it is possible to estimate cropwater requirements, root distribution patterns, andperiods when fertilizers have a high probability ofleaching.

In the Thailand project, water regimes of severalcrops— rice, cotton, maize, sorghum, and soybeans, forexample — are being studied under different croppingconditions. Although the total amount of rainfall is more

than sufficient for rainfed agriculture, its distribution iserratic and the rainy season allows only the cultivation ofone crop. Dry spells of one or two weeks within the rainyseason severely affect productivity because the soilshave a low capacity for retaining water. Root distributionsare generally shallow, which also diminishes the availa-bility of water and fertilizer. Common heavy rains, severaltimes depositing more than 50 millimetres, causenutrient leaching, mainly of costly chemical fertilizer.Erosion is also a problem.

Suitably calibrated gamma probes can be used tomeasure soil bulk density distributions in soil profiles.The diagnosis of compaction layers that impede rootgrowth is made from these density profiles.

The use of fertilizer labelled with nitrogen-15 allowsestimation of the efficiency by which the crop uses fertil-izer and how much is leached. Labelling organic matteropens the possibility of studying the fertilizer's rate ofdecomposition in the soil and its fate in the biologicalcycle in which the crop develops.

Many soil and water conservation practices are beingtested in field trials. Some of these experiments evaluatethe effects of compost, green manure, and othermaterials on increasing the soil's water retention charac-teristics, promoting a deeper root distribution, and sup-plying nutrients to crops. Different soil tillage methodsare being tested for different soils, slopes, and crops tofind management practices that conserve the soil,optimize their water economy, and promote extension ofthe growing season so that more than one crop can becultivated.

Prof. Reichardt, a former FAO/IAEA staff member, is full profes-sor at the University of Sao Paulo at Piracicaba, Centre deEnergia Nuclear na Agriculture, in Brazil. In November 1986, heserved as an FAO/IAEA expert for the Thailand project.

AEA BULLETIN, 4/1987 47

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Strong tradition

Nuclear techniques applied to the solution of practicalagricultural problems have strong tradition in Thailand. Itbegan shortly after 1955, when two recommended ricevarieties were irradiated in the United States to inducemutations having better grain quality and diseaseresistance. As a result, three improved mutant rice varie-ties were released in Thailand during the mid-1960s.Later, work on improvement of food legumes, ThaiKenaf, soybean, jute, cotton, and sugar cane wasinitiated using gamma irradiation and, as being donetoday, with related tissue culture techniques.

The Department of Agriculture established a Radio-isotope Laboratory in its Chemistry Section in 1959, andphosphorus-32 was used to evaluate the nutrient's utili-zation in rice and soybean. As was the case with the earlymutation breeding work, the soil-plant studies laterbecame part of a number of co-ordinated researchprogrammes of the IAEA and Food and AgricultureOrganization following establishment of the JointFAO/IAEA Division in 1964. From 1962-74, many fieldexperiments at the Surin, Rangist, and Bangkhen RiceExperimental Stations were carried out usingphosphorus-32 and nitrogen-15 to assess the efficientutilization of phosphate and nitrogen fertilizers. Isotope-aided research was also conducted on micronutrients,utilization of naturally occurring rock phosphates, and onfertilizer efficiency in other crops.

The Thai Government recognized early the impor-tance of reproductive hormone analyses by radioim-munoassay (RIA), or by the related enzymeimmunoassay, for studies of livestock health andreproduction. The analyses were used for early preg-nancy testing, oestrous synchronization, and improvingmanagement strategies to accelerate puberty andreduce post-partum periods of anoestrus in livestock.

Buffalo and other livestock can be studied using nucleartechniques to improve their reproductive efficiency.

The focal point for this work has been ChulalongkornUniversity. Other research activities have focused on thesafe and efficient use of pesticides, and on the applica-tion of food irradiation processing to preserve foodstuffs.Throughout the past 20 years, Thai scientists havereceived specialized training through FAO/IAEA's fellow-ship programme and training courses in these and otherfields.

In 1964, scientists conducted the first isotope-aided experi-ment in Thailand on rice fertilization.

The isotope phosphorus-32 being used in root distributionstudies in Thailand.

48 IAEA BULLETIN, 4/1987