1

ECONOMIC STUDY OF FARMLAND EROSION

CONTROL PRACTICES IN ENUGU STATE,

NIGERIA

BY

EZE SILAS OZOEMENA

PG/M.SC/06/41581

DEPARTMENT OF AGRICULTURAL ECONOMICS

FACULTY OF AGRICULTURE

UNIVERSITY OF NIGERIA, NSUKKA

SEPTEMBER, 2012

i

TITLE PAGE

ECONOMIC STUDY OF FARMLAND EROSION CONTROL

PRACTICES IN ENUGU STATE, NIGERIA

A THESIS

SUBMITTED TO THE DEPARTMENT OF AGRICULTURAL

ECONOMICS UNIVERSITY OF NIGERIA, NSUKKA IN

PARTIAL FULFILLMENT OF THE REQUIREMENTS

FOR THE AWARD OF MASTER OF SCIENCE IN

AGRICULTURAL ECONOMICS

BY

EZE SILAS OZOEMENA

PG/M.SC/06/41581

SEPTEMBER, 2012

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DEDICATION

This research work is dedicated

to

God Almighty

and

My beloved wife and Daughter Mrs. Eze Lucy, Chinelo and Little Miss Eze Favour Akachukwu.

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CERTIFICATION

Eze Silas Ozoemena a postgraduate student of Department of Agricultural

Economics with registration number PG/M.Sc/06/41581 has satisfactorily completed the

requirement for the course and research work for the award of Master of Science (M.Sc)

in Agricultural Economics. This research work has been approved for the Department of

Agricultural Economics, University of Nigeria, Nsukka.

----------------------------- ---------------- --------------------------- -------------

DR. A.A. ENETE DATE PROF. E.C. OKORJI DATE

SUPERVISOR HEAD OF DEPARTMENT

------------------------------------- -----------------

PROF. J.A. MBANASOR DATE

EXTERNAL EXAMINER

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ACKNOWLEDGEMENT

With heart full of joy, I first of all appreciate God Almighty who in his infinite

mercy and love has provided me with abundant spiritual and material protection and

guidance throughout the period of this porgramme.

I am very much indebted to my industrious and articulate supervisor Dr. A.A.

Enete for his constructive criticism, thorough supervision and advice that has brought my

dissertation to a logical conclusion. May God shower him and his family with abundant

blessings.

However, I must not forget in a hurry the programme Manager ENADEP Mr.

Onyemaechi Nwodo and the man incharge of monitoring and evaluation unit, Enugu

State FADAMA programme Mr. Michael Nwobodo who provided me with the materials

and assistance of the Agricultural extension agents of three agricultural zones of Enugu

State in the persons of Mr. Walter Oti (Enugu North), Uche Okonkwo (Enugu East) and

Charles Nnaji (Enugu West). It is well with them.

My sincere appreciation also goes to; Prof. Akamigbo, F.OR., Ofomata G.E.K.

Prof. Okoye, C.U., Dr. Ozor, N., Mr. Onyekuru Anthony, Eze Emmanuel IK, Ade, and

host of others for providing me with some useful materials that guided my research work.

Finally, I am not forgetting to thank my typists, friends and well wishers

particularly my family members headed by Mr. Alfred Eze for empowering me with

human and material resources throughout my academic pursuit. May God reward them

million folds and shower them with his favour.

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TABLE OF CONTENTS

CHAPTER ONE

1.0 INTRODUCTION - - - - - - - 1

1.1 Background of the Study - - - - - - - 1

1.2 Statement of the Problem - - - - - - - 5

1.3 Objectives of the Study - - - - - - - 7

1.4 Research Hypotheses - - - - - - - 7

1.5 Significance of the study - - - - - - - 7

CHAPTER TWO

2.0 Literature Review - - - - - - - - 9

2.1 Concept of soil erosion - - - - - - - 9

2.2 History of soil erosion - - - - - - - 12

2.3 Mechanism of soil erosion - - - - - - 14

2.4 Economics of soil erosion - - - - - - - 17

2.5 Factors responsible for erosion in Enugu state - - - - 20

2.6 Classification of erosion - - - - - - - 24

2.7 Erosion control - - - - - - - 30

2.8 Problems and effects of erosion - - - - - - 35

2.9 Documentation of erosion site in Enugu State - - - - 40

2.10 Review of existing erosion control practices - - - - 42

2.11 Theoretical framework - - - - - - - 47

2.12 Analytical framework - - - - - - - 54

2.12.1 Multinomial logit model - - - - - - 54

2.12.2 Partial budgeting - - - - - - - 57

2.12.3 Duncan‘s multiple-range test - - - - - - 60

CHAPTER THREE

3.0 Methodology - - - - - - - - 61

3.1 The Study Area - - - - - - - - 61

3.2 Sampling Procedure - - - - - - - 62

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3.3 Data Collection - - - - - - - - 63

3.4 Data Analysis - - - - - - - - 63

3.5 Test of Hypothesis - - - - - - - 63

3. 6 Model Specification - - - - - - - 64

3.6.1 Multinomial Logit Model - - - - - - 64

3.6.2 Partial Budget Analysis - - - - - - - 66

3.6.3 Duncan‘s Multiple Range Test - - - - - - 68

3.6.4 Likert rating scale technique - - - - - - 69

3.6.5 Profitability index - - - - - - - 69

CHAPTER FOUR

4.0 Results and Discussion - - - - - - - 70

4.1 The erosion control practices applied by farmers in the area - - 70

4.1.2 Combination of erosion control practices applied by farmers - - - 71

4.1.3 Description of Farmland Erosion Control practices applied by Farmers- 72

4.2 Costs and returns for the erosion control practice - - - 74

4.2.1 Multiple Cropping Partial Budget - - - - - 74

4.2.2. Construction of Bonds - - - - - - - 75

4.2.3. Ridging Across the Slope - - - - - - 76

4.2.4 Cover Cropping - - - - - - - - 77

4.2.5 Duncan‘s Multiple Range Test - - - - - - 79

4.3 Socioeconomic Factors Affecting Farmer‘s use of Particular Erosion Control 80

4.4 Possible Causes of Erosion on the Farmland from the Farmers Perspective 84

4.4.2 Causes and extent of cause of erosion as perceived by the farmers - 87

CHAPTER FIVE

5.0 Summary, Conclusion and Recommendations - - - - 90

5.1 Summary - - - - - - - - - 90

5.2 Conclusion - - - - - - - - 92

5.3 Recommendations - - - - - - - - 93

REFERENCES - -- - - - - - - 95

APPENDIX - - - - - - - - - 115

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LIST OF TABLES

Table 4.1.1 Frequency, Percentage and Rank Distribution of

Farmland Erosion Control Practices. - - - 71

Table 4.1.2 Frequency and Percentage Distribution of Combination of

Erosion Control Practices. - - - - - 72

Table 4.2.1 Multiple Cropping Partial Budget - - - - 75

Table 4.2.2 Construction of Bonds Net Benefits - - - - 76

Table 4.2.3: Ridging Across the Slope Partial Budget - - - 77

Table 4.2.4 Cover Cropping Partial Budget - - - - - 78

Table 4.2.5.1 Duncan‘s Multiple Range Test for Net-Benefit - - 80

Table 4.3.0 Result of Multinomial Logit Regression Analysis of the

Socioeconomic Characteristics Affecting the Farmers Use of Multiple

Cropping, Construction of Bonds, Ridging Across the Slope, and Cover

Cropping in Enugu State - - - - - - 83

Table 4.4.1 Frequency and Percentage Distribution of the Possible Causes of

Erosion on the Farmland. - - - - - 86

Table 4.4.2.1: Mean and Standard deviation Distribution of the Perception of

Extent of Causes of Farmland Erosion by the Farmers. 89

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FIGURES

Fig. 1: Technology Options for Erosion Management on Newly Cleared Land 46

Fig. 2: Soil Erosion Map of South Eastern Nigeria - - - - 111

Fig. 3: Potential Erosion Map of South Eastern Nigeria - - - 112

Fig.4: Soil Type Map of Enugu State - - - - - - 113

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ABSTRACT

An economic analysis of farmland erosion control practices was conducted in Enugu

State, southeastern Nigeria. The study aimed at identifying and describing the erosion

control practices applied by the farmers, determining the net-benefit of erosion control

practices, determining the socio-economic factors affecting the farmers‘ use of a

particular erosion control practice and identifying from the farmers perspective the

possible causes and extent of cause of erosion on the farmland as well as making

recommendations based on the findings. An interview schedule and structured

questionnaire were used to elicit primary data from 168 farmers, randomly selected from

the three agricultural zones of the state. Analysis of the data were done using multinomial

logit model, partial budget analysis Duncan‘s Multiple range test and descriptive

statistics. Four erosion control practices were used by the farmers: Multiple cropping, as

indicated by 41% of the respondents, Construction of Bonds, 20%, Ridging across the

slope, 18% and Cover cropping, as indicated by 21% of the respondents. The Partial

budget analysis showed the net-benefits of each of these erosion control practice as N393,

953.88k for Multiple cropping, N26, 115.30k for Construction of Bonds, N33, 741.66k

for Ridging Across the slope and N891.10k for Cover cropping. 7.36 (Multiple cropping),

1.59 (Construction of bonds), 1.14 (Ridging across the slope) and 1.10 (Cover cropping)

were shown as the profitability index for the erosion control practices. Duncan‘s

comparison test showed that there was statistically significant difference in the means of

net-benefits of erosion control practices at 5%. The Multinomial logit Regression analysis

indicated a seemingly low explanatory powers of the factor as reflected by Pseudo- R2 of

0.2449, but this is not uncommon in cross sectional analysis. The overall goodness of fit

as reflected by prob>Chi2 was however good (

1

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

A dramatic acceleration in population growth has taken place in sub-Saharan

Africa since the 1960s (World Bank, 2006). The increasing demand to feed this growing

population has lead to resource use intensification (Junge, Birte, Abaidoo. Chikoye ,D.

Alabi ,T. and Stahrand Karl,(2006). and Non- adaptable land use practices which lead to

soil degradation (Hudson, 1995). In sub-Saharan Africa, soil degradation has already

become the most critical environmental problem (Mbagwu,Lal, and Scott,(1984) Eswaran

,,Lal and Reich,( 2001). Soil erosion is one manifestation of soil degrading processes that

results in reduced soil quality and productivity (Akamigbo, 2001, Morgan, 1995, Lal,

2001). There is an urgent need to combat the accelerating trend of soil degradation, to

maintain soil productivity and to contribute to the food security of current and future

generations (UNEP, 1997).

Ecological disasters rank high among factors which encourage inefficient

utilization of resources in Nigeria and limit the country‘s development potential. They

occur in various forms but typically include droughts, soil and wind erosion, flooding, oil

pollution and bush fires. Soil erosion is one of the most important physical problems

affecting our development in this part of the world today. Apart from the fact that it

constitutes a menace to the environment and its destruction of our infrastructures-high

ways, big structures etc, it creates a major problem in our agricultural soils, thereby

interfering seriously with the mass food production campaign. We cannot afford to over-

look these problems created on our soils by soil erosion because there is no real evidence

that we may some day detach our lives from the soils. It is the soils that sustain us

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because soils are the foundation of our worldly goods-a basic wealth upon which our

existence as inhabitants of the earth depends (Akamigbo 1987).

The web definition of erosion says it is the wearing away of the earth‘s surface by

running water, wind, ice, or other geological agents, processes, including weathering,

dissolution. Akamigbo (1988) defined erosion as a systematic removal of soil, including

plant nutrients, from the land surface by the various agents of denudation. According

Ofomata (1988), soil erosion can be regarded as merely a geomorphologic process,

whereby the surface layer of weathering rock is loosened and carried away by wind or

running water and a lower horizon in the soil is exposed.

Soil erosion occurs in several parts of Nigeria under different geological, climatic,

and soil conditions. The degree of occurrence varies considerably from one part of the

country to the other. Soil erosion occurs all over southeastern Nigeria. The incidence of

soil erosion in southeastern Nigeria especially Enugu state is not new, as it has formed a

subject for serious consideration since the beginning of this century. For instance, the Udi

forest Reserve was created in 1922, followed by an Anti-Erosion plantation, also at Udi,

in 1928 (Sykes, 1940), all aimed at combating the nefarious effects of soil erosion as

highlighted by the general review of the state of soil erosion in Nigeria by late Sir.

Dudley stamp in 1938. Stamp‘s review was followed by the special study of the

phenomenon by Grove (1951) in part of former Eastern Nigeria as well as by Ofomata in

some greater detail in parts of southeastern Nigeria (Ofomata, 1964, 1965, 1966, 1967,

1973, 1980, 1981a, 1981b, 1981c, 1982, 1984, 1985a, 1985b and Stone, 1996). Soil

erosion is a major limitation to sustainable production in most farmland of Africa (Lal,

1995) in general and southeastern Nigeria (Enugu State) in particular. It ranks as one of

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the most serious problems on agricultural lands, threatening large populations with

starvation (Oti 2002). Studies have shown that soil erosions is by far the most severe

hazard affecting the lands of Nigeria, ravaging all of its bio-climatic regions as rill, sheet,

and gully erosion (Ofomata 1964,1980,1982,1984a, and b, Ologe, 1971: Oganuga 1978, ,

Anon, 1988). Soil erosion causes the loss of a tremendous amount of valuable soil, (Kio

and Okorie (1986). It has been estimated that about 30 million tones of soil are lost

annually throughout the country with the eastern states losing over 15million tones,

(Onyeagocha, 1980, Okorie and Adeola, 1985). The depletion of agricultural land

resources occurs through different forms of land degradation namely, leaching of

nutrient, erosion by water which has led to devastating gullies in some parts of the

country especially southeast, drought and wind erosion resulting in desert encroachment

in the northern parts of the country and wastage of land by flood and coastal erosion,

(Akamigbo, 2006). As soil becomes depleted by water erosion, people attempt to move to

other more productive land. Eventually, when there is no more land available they are

forced to adapt themselves to smaller amounts of food which require harder work to

grow. This condition lead to malnutrition and hopelessness. (FAO 1965). Erosion, as an

environmental hazard has numerous adverse economic effects on the lives and livelihood

of people. Generally it results in a degradation of the environment, and reduction in land

area available for habitation, agriculture, industry, recreation, road construction, as well

as loss of soil fertility. Furthermore, erosion also leads to pollution and blocking of

waterways, loss and destruction of social centers, and social amenities. (Ezebube, 1989

and Akamigbo, 1999). Soil erosion also leads to pollution and blocking of waterways,

loss and destruction of social complex process that depends on soil properties, ground

slope, vegetation, and rainfall amount and intensity (David, 2007).

4

The major environmental cause of soil erosion in southern Nigeria is rainfall with the

mean annual rainfall reaching about 3000mm in some parts and with rainstorms often of

long duration and intensities which may be up to 200mm-1

, it would be expected that the

erosivity factor plays a dominant role in the soil loss problem (Obi and Asiegbu, 1980).

Controlling erosion on productive land must usually be done while growing crop.

Therefore many control measures are closely related to ordinary methods of agriculture.

The common ones are land use, cropping systems, cover crops, fertilizers and

manures, ridging across the slope, construction of bonds, grassing of water ways, hedge-

row planting / vetiver grass and tillage practices (FAO, 1965., Akamigbo, 1988, 1998.,

Ofomata, 1988., Chude, 2005., Lal 1995., ENADEP, 2007). Management of soil for

water and wind erosion control is based on sensible soil conservation practices. The

majority of these practices are recognized components of good soil, crop, and water

management for effective erosion control. It is important to maintain good soil structure,

protect the soil surface by adequate crop and residue cover, and use special structural

erosion control practices where necessary. These factors often control both water and

wind erosion. Not all erosion control practices will fit into every farm management

scheme. However, each erosion problem can be remedied by choosing one or more of the

remedial practices appropriate to the problem. (Stone, 1996). Of all types of erosion the

most pernicious and serious on the farmland in the southeast is the sheet erosion. It

causes the gradual but significant losses of soil particles and mineral nutrients which are

carried away in surface run-off during rainfall or blown away as loose particles by strong

winds in drier areas. The activities of man and other land animals, which destroy

vegetation cover, predispose the soil to accelerated sheet erosion. For instant, the hooves

5

of cattle in any fragile soil environment pulverize the soil as they move and render the

soil susceptible to both wind and water erosion, (Akamigbo, 2006).

1.2 Problem Statement

Farm land erosion poses a very serious set back to farmers in Enugu state and the

extent of the spread and damage have reached an alarming proportion that if efforts are

not intensified to remedy the ugly situation, it could cause untold hardship and put the

communities in a state of jeopardy. It has been estimated that available arable lands in

the states of the southeastern Nigeria have been reduced by 50% as a result of erosion

(Braide, 1982). Erosion leads to the pollution and destruction of the environment. Rural

water supply from streams is also constantly being polluted by heavy sediment load,

thereby adding health hazard to the problem of damage to infrastructure (Akamigbo,

1999). Some of the most ravaging erosion related environmental hazards are found in

many parts of the southeast, especially Anambra, Enugu and Imo states (Ofomata, 1985,

Akamigbo, 1988 and Ogbukagu, 1986). Many farmlands from which majority of the

households earn their livelihood are especially affected; a situation which has led to thigh

population pressure on the available land (Onuora, 1985, Ezebube, 1989, and Akamigbo

1999). This condition according to them have inflicted great losses in the production

potentials, crop land, crop quality, biodiversity, genetic resources as well as excessive

field fragmentations.

The economic cost of erosion is very difficult to quantify, but it is definitely very

large, Huge sums of money are spent each year repairing damage caused by erosion or

reinforcing existing structures and land against erosion, (Akamigbo, 1999).

Money that should be used by rural farmers in Enugu state for solving their family

problems is spent on erosion control.

6

Erosion control is usually expensive and many efforts have been made by

successive governments to control erosion in southeastern Nigeria but not much success

have been achieved. This could be attributed to lack of proper understanding of the

techniques involved in handling erosion control. Agro-engineering findings indicate that

farmers in the rural southeastern Nigeria apply many techniques to conserve soil, control

erosion and prevent soil degradation. (Onuoha, 1985 and Ofomata 1982). Young (1989)

states that the costs or labour requirements of physical erosion control works necessary to

control run-off by such means as bunds and terraces were commonly found to be

expensive. ―Conservation farming‖ or ―integrated land use‖, the emerging farming

systems approach to environmental conservation, has been practiced by Nigerian farmers

for a long time (Okoye, 2001).

Young (1989) advocated the use of simple methods of erosion control such as

mulching, bunding, and cover cropping, which are within the capacity of the farmers to

establish and maintain, and endorses external support for sound traditional farming

practices. Despite the awareness of these traditional techniques and management actions

of the local farmers to control erosion and protect the environment, they have remained

largely under studied, unexplored and neglected especially with regards to the economic

evaluation of these indigenous techniques. (Reiji 1990, Eboh 1991).

Although, Utazi (2002) carried out an economic study of farmland erosion control

practices in Imo state where he identified the different erosion control practices used by

farmers in the area and determined the cost benefits of erosion control practices, he failed

to describe from the farmers perspective the possible causes of erosion on the farmland as

well as determining the socioeconomic factors affecting the farmers use of a particular

erosion control practice. Another missing value is the difference in location of the study.

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This study therefore aims at addressing these missing links in Enugu state.

1.3 Objectives of the Study

The broad objective of this study was to conduct an economic analysis of

farmland erosion control practices in Enugu State. The specific objectives are to;

i. identify and describe the erosion control practices (or combination of practices)

applied by farmers in the area.

ii. determine the net benefit of erosion control practices.

iii. determine the socioeconomic factors affecting the farmer‘s use of a particular

erosion control practice.

iv. identify from the farmer‘s perspective the possible causes of erosion and extent of

cause on the farmland.

1.4 Hypotheses

In line with the specific objective this research was guided by the following null

hypotheses;

1. There is no relationship between the socioeconomic characteristics of the farmers

and the type of erosion control practices used.

2. There is no significant difference between economic benefit of different erosion

control practices by the farmers.

1.5 Justification of the Study

The study will provide information to farmers on the net benefits of farmland

erosion control practices for increased crop productivity and food security. Measures

aimed at controlling farmland erosion will to a large extent save soil fertility, economic

trees and crops and farmland from being devastated. The knowledge of the economics of

8

erosion control measures will guide the policy makers in quantifying the control practices

for future planning.

On the other hand, information on the economic analysis of farm land erosion

control practice will equip the Environmental Protection Agency (EPA),in formulating

appropriate environmental related policies in order to ensure environmental

sustainability. Achieving certain standards of erosion control, will provide information

about the value given to land in the market to erosion control, what will help investment

decision.

Finally, other researchers that are interested in searching for solutions of the

devastating effect of erosion will be assisted with the information that will be provided in

the study. It will invariably provide information on how best to increase the farm land

value in other to consequently increase its productivity and alleviate poverty.

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CHAPTER TWO

2.0 LITERATURE REVIEW

The literature was reviewed under the following captions:

2.1 Concept of soil erosion

2.2 History of soil erosion

2.3 Mechanism of soil erosion

2.4 Economics of soil erosion control.

2.5 Factors responsible for erosion in Enugu state.

2.6 Classification of erosion

2.7 Erosion control

2.8 Problem and effects of erosion

2.9 Documentation of erosion site in Enugu state.

2.10 Review of existing erosion control practices

2.11 Theoretical framework

2.12 Analytical framework.

2.1 Concept of Soil Erosion

Several definitions has been given to erosion as a concept from different

perspective.

Definitions of erosion from the web: The wearing away of land or soil by the action of

wind, water or ice.

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The wearing away of land surface by water, intensified by land-clearing practices related

to farming, residential or industrial development, road building or logging. The gradual

diminishing of land or soil as a result of the action of water wind rain etc.

‗ Erosion‘ comes from erodere, a Latin verb meaning ― to gnaw‘ Erosion gnaws

away at the earth like a dog at a bone. This has given rise to pessimistic view of some

writers who see erosion as a leprosy gnawing away the earth until only a whitened

skeleton is left (Roose1996). Holy (1982), opined that erosion is manifested by the

deterioration of soil surface affected by exogenous forces. According to Mumel (1992),

erosion is the removal of surface material from the earth crust, primarily soil and rock

debris and the transportation of the eroded materials by natural agencies from the point of

removal. Goudre (1990), saw erosion as the most destructive process that acts to reduce

productive farmland. Wood (1995), defined erosion as the wearing away of the soil

surface by running water, wind, ice or other geological agents, including such processes

as gravitational creep, detachement and movement of soil and rock fragments by water,

wind, ice or gravity. Dike (1995) stated that erosion is a natural phenomenon which is the

wearing away of the earth‘s surface by water, ice or other natural agents under natural

environmental conditions. Lal (1990) defined erosion as the washing and blowing away

of the top soil by running water and wind respectively. Middleton (1990) defined erosion

as detachment and transportation of soil particles by water and wind.

Erosion is a natural process which indeed wears down all mauntains ( also

referred to by the English school as the denudation rate, which is the lowering rate of the

soil level), however, at the same time erosion enriches valleys and forms the rich plains

that feed a large part of humanity, (Roose, 1996). It is therefore not necessarily desirable

11

to stop all erosion, but rather to reduce it to an acceptable or tolerable level.Ofomata

(1988) categorized the factors of soil erosion in south-eastern Nigeria into two

components: Physical (geological or natural) and Anthropogenic (human or accelerated).

Close study has, however, revealed that the human component in soil erosion is often

exaggerated while the effects of the physical component are usually underestimated

(Ofomata, 1965 and 1978)

Roose(1996), stated that Normal or geological erosion (morphogenesis) is

generally defined as the process that slowly shapes hillsides, allowing the formation of

soil cover from the weathering of rocks and from alluvial and colluvial deposits

(pedogenesis). Roose (lbid) on the other hand, opined that erosion accelerated by human

activities, following careless exploitation of the environment, is 100 to 1000 times faster

than normal erosion.

Oradiegwu (1980) grouped soil erosion into two classes, gully and sheet erosion.

His classification was based on the depth to breadth ratio to the surface affected. When

the depth of the erosion is negligible in relation to its breadth, the erosion is referred to as

sheet erosion. On the other hand, when the depth of the erosion is significant in relation

to its breadth, it is called gully erosion. Whenever there is surface run –off, there must be

sheet as well as linear erosion. According to Forth (1984), the soil carried away by

erosion frequently ceases to be of value in crop production. Furthermore the remaining

soil denude of the surface or pillow layer is much decreased in productivity, in comparing

the nutrient losses through erosion and its uptake by plants, the loss of nutrients by

erosion even on a 4% slope, may easily exceed the removal of nutrients by crops

12

occupying the land. Arakeri, (1959) also stated that the fertility losses by erosion have

been estimated to be 20 times greater than losses through the crop removal or leaching.

Ofomata (1981) evaluated the impact of erosion upon local environmental

knowledge and indigenous systems of management and organization. His general

consensus is that indigenous soil and water conservation practices forms an indispensable

starting point for the development of counter erosion projects.

The case of studying traditional erosion prevention and control practices in

southeastern Nigeria, is self evident. The failure of ―top down‖ projects have led to

increased call for ―bottom top‖ projects that would be farmer based, cost effective and

locally sustainable (FDALR, 1990).

2.2 History of Soil Erosion.

Erosion is an old problem. From the time land emerges from the seas, it is lashed

by the forces of wind, waves and rain, (Roose, 1996). Erosion is as old as agriculture,

(Amechi ,1997 and Edward, 1993). The Nigerian civil war 1967-1970 did not only take

its toll of human lives but left many plantations, forest reserves and farmlands devastated

and unprotected. Massive refugee camps usually constructed under thick forest covers

turned into gulling areas even when the inmates were still in settlement. The operations

of the ‗land army‘ by farming on every available land space created an additional

favourable environment for serious sheet and rill erosion, both of which were precursors

to many of the present gullies in Anambra and Enugu state, (Akamigbo, 1988).The

decisive epoch of the development of soil erosion according to Holy (1980) began when

man settled down and began turning pasture land into farms. The intensive exploitation of

13

the land disturbed the natural soil vegetation cover and exposed the surface to the effect

of erosion agents and introduced such forms of agriculture that did destroy the land.

The present land mass known as Anambra and Enugu state had been bedevilled

by the menace of gully and sheet erosion long before the arrival of the British colonial

Government. Gullies by their nature are more perceptible and spectacular. Those at udi,

Nanka, Adazi, Alor, Oraukwu and Agulu are older than 150 years, predating any living

human being in the areas concerned. The efforts of the colonial government in stabilizing

some of these degraded areas at Enugu and Udi (the capital territory of former Eastern

Nigeria) dated back to the 1920s. (Akamigbo, 1988).In 1928, erosion control work was

started in Udi by treating the badly eroded areas with simple mechanical devices

combined with planting of seeds of Actio barteri, Anacardium occidentale,

Erythrophleum svaveolens and Pentaclethra macrophylla, (Okafor,1986).

As early as 1944, the geographic harmony had clearly realized why ―Africa is a

dying land‖. It was dying as a result of the destabilizing methods of colonial systems

which intensified soil use, hastened removal of assimilable nutrients and mineralization

of organic matter, and pushed the indigenous people on the poorest and most fragile land,

reducing the length of fallow periods (Roose, 1996).

During the Biafran war, the cohesionless soil mass of southeast was subjected to

motar bombardments in addition to series of deep trenches which were not refilled. It was

not surprising then that the first environmental problem experienced by the people of

Anambra. Enugu, Imo and Akwaibom states immediately after the civil war was the

upsurge of serious sheet and gully erosions. (Akamigbo,1988).

14

The deceptive sheet erosion was more devastative and crop yield was rapidly

decreasing. The cries for help spread quickly from one village to the other. The then

federal military Government in 1974, intervened by signing a contract with an Italian

firm of consultants, technical S. P. A. Rome and Nigeria techno Ltd Lagos to undertake a

per-feasibility study of the parts of the then East central state in order to determining the

cause and seriousness of soil erosion in the state.(Akamigbo, 1988).

Soil erosion menace in Enugu state has therefore continued unabated to take its

wants toll of indispensable soil and water resources, civil infrastructures, property and

life and has placed agriculture and the entire environment in a very serious jeopardy. The

situation continues to assume more catastrophic dimensions as the rains come and go

every year.

2.3 Mechanism of Soil Erosion.

Soil erosion requires energy, and the energy of an intense rainstorm is

tremendous. The energy from raindrops packs the bare soil surface and disperses soil

aggregates. The dispersion products (Mostly clay) are washed into surface voids and

along with the packing done by the raindrops form a film at the soil surface. The

permeability of this film is very low, and most of the water begins to run off in sheets

after it is formed. These sheets of water have virtually no carrying capacity for soil

because they are so thin. However, when the energy of raindrops is added to these sheets

in the form of turbulence, the carrying capacity is increased manifold. The dispersed

material released from the aggregates is carried off resulting in so-called sheet erosion,

which is responsible for most of the erosion from crop land soils, (FAO, 1965).

15

Holy (1980), stated that erosion is manifested by the deterioration of soil surface

affected by exogenous forces, especially water, ice, wind and man as the significant

anthropogenic factor. He went further to state that the disturbance of the soil surface is

accompanied by the removal of detached soil particle by the forces of kinetic energy of

the erosion agent namely water and wind and the depositions of these materials with a

decrease in the energy.Erosion is basically an interactive process. The interactors are the

failing raindrop or flowing water on the land, and the soil on the other. The energy of the

raindrop or flowing water has the ability to detach and transport the soil particles. This

ability is referred to as Erosivity of the water. On the other side of the interaction is the

soil, whose particles may or may not yield to a given level of erosivity. The measure of

the ease or difficulty of detachment (and transport) of soil particles under erosive

influence is referred to as Erodability. Therefore for erosion to occur, the water must be

erosive and the soil must erodable, (Akamigbo 1998).Lal (1986) described soil erosion by

water as a work process involving two phases; detachment of soil particles and their

transport. He stated that soil detachment involves the removal of transportable fragments

of materials from a soil mass by raindrop impact or shearing forces of overland flow. On

the other hand, transport or entrainment of detached primary or secondary particles occur

through splash and overland flow.

The process of sheet erosion consists of two essential component; rain splash

erosion and surface wash. Rain splash erosion is due to the impact of raindrops on the

ground surface. As a rain drop hits the soil, it tears loose particles of soil and kicks them

into the air. Most of the soil particles land away from the point of impact with more of

them landing on its down slope than on its upslope side. Thus, the net result is the

16

downward slope translocation of soil particles. The process is also important in aiding

surface wash by loosening the soil and making the particle available for transportation.

Surface wash is the process whereby water running down the slope as a turbulent sheet

removes particles of soil and carries them away. This surface runoff occurs during and

immediately after rain storms in which the rainfall intensity exceeds the soils infiltration

capacity (Ologe, 1986).Raindrop on striking the soil surface, expends its kinetic energy in

detaching soil particles. According to Wischmeier (1959), the erosion generating power

of the raindrop is the product function of the raindrop energy and the maximum 30-

minute rainfall intensity.

Running water is the main agent of erosion in the Enugu state and the process of

erosion depends on the manner in which runoff is organised over space. The mechanics

of erosion in the area also vary with the types/process. Sheet erosion occurs where runoff

is unconcentrated but rather flows as a thin sheet over the entire surface or over a good

proportion of that surface. Gully erosion occurs where runoff is concentrated along

definite channels. The gullies lengthened by headward erosion, also known as head-scarg

retreat and widens through basal sapping leading to the collapse of materials on gully

walls in the form of sliding and or slumping, (Ofomata, 1986).

Rain tends to run off surface of the soil in deforested or over-grazed areas,

thereby removing the top soil. Deforestation and over-grazing remove the original

vegetation which breaks the fall of rain and also supplies the topsoil with the humus

which allows rapid absorption of water. Rain which falls on unprotected soil tends to clog

the normal openings of the soil with bits of silt, so that the run off is increased. Run off is

the part of rainwater which does not sink into the soil, but flows away over the surface to

17

steam or rivers or oceans, (Akinsanmi, 1975). The wind exercises a pressure on solid

particles in repose. This pressure is exerted above the centre of gravity on the surface

exposed to wind and is opposed by a friction centred on the base of the particles. The two

forces combined tend to lock particles (0.5 to 2mm) and make them roll, (Roose, 1996).

Moreover, the difference in speed between the top and bottom of particles means

that they are drawn upwards. The lighter particles rise vertically until the gradient of

velocity is too low to bear them, at which point, they fall back pushed by the wind,

following a sub-horizontal curve. As they fall, these grains of sand transmit their energy

to other grains of sand (as in a game of bowls) or degrade loamy clay aggregates,

releasing dust (Heusch 1988).

2.4 Economics of Erosion Control

It has become very clear in recent times that soil conservation schemes has

continued to reduce the amount of soil carried away by erosion and can answer the needs

of farmers in tropical region. Indeed, experts have been saying for a long time that soil

has to be conserved so as to maintain the productivity of land; thus the title of the fifth

ISCO conference (Bangkok, 1988) was ―land conservation for future Generation‖.

Farmers (not always of their own volition) have undertaken to devote considerable efforts

to schemes to control erosion on their land, but have been disappointed to see that their

land still deteriorated and crop yields still fell. The erosion control structures imposed

(drainage ditches, diversion channels, bunds) have often reduced the arable land area (by

3% to 2%) without any equivalent improvement in the productivity of ―protected‖ plots.

If farmers are to be motivated, it is not enough to keep the soil in place, water must be

18

managed and soil fertility restored in order to see a significant increases in yields from

these tropical soils, the majority of which are already very poor (especially tropical

ferralitic and ferruginous soils that are sandy on the surface) (Roose, 1996).

Soil erosion is a major environmental threat to the sustainability and productive

capacity of agriculture. During the last 40years nearly one third of the world‘s arable land

has been lost by erosion and continues to be lost at a rate of more than 10 million hectares

per year. With the addition of a quarter of a million people each day, the world

population‘s food demand is increasing at a time when per capita food productivity is

beginning to decline (David et al 2007).The brain behind conserving the soil is for

environmental sustainability and the survival of mankind. The implacable nature of soil

does not permit us to have a purely economic view point of soil conservation. Every

piece of land has a certain market value that is related to its present and potential

productivity. But actually, the intrinsic value of land is much greater than money, it lies

on its ability to feed and clothe man for countless centuries. This can not be expressed in

monetary terms (kohnke and Bertrand, 1959). The most important characteristic of land

resource is the relationship between the amount of soil lost and the land productivity

(Mbagwu, 1986).Gully erosions processes cause damage to many branches of the

economy of a nation and much of these damages especially the social consequences is

difficult to express in numerical values (Holy, 1980). One of the major contemporary

challenges facing environmental scientists and policy makers is the growing enormity of

resource degradation and related soil erosion problems in part of sub-Saharan Africa.

These challenges becomes more glaring considering that the region loses about six tons

of soil to erosion each year (steri-Younis, 1986).

19

In Nigeria, some of the most devastating erosion related environment hazards are

found in many parts of the southeast especially Anambra, Enugu and Imo States

(Ofomata 1981 and Ogbukagu, 1986). Over half of the total land area is believed to suffer

different forms of erosion ranging from mild sheet wash, severe sheet wash to gulling

processes. Sheet erosion of the humose topsoil causes fertility decrease because the

topsoil contains most of the nutrients needed by the plants to grow. The cost of

replenishing these nutrients is quite high and when they are not replenished, poor crop

yields results (Akamigbo, 1999). According to Risser (1985), erosion is a massive

hidden‖ cost on the economy of any community and as erosion increases, so do food

costs. Farmers must then apply more chemicals to the land in order to compensate for the

fertility loss caused by erosion and must spend more money for tillage activities because

eroded soils are more compacted and difficult to till.

Conservation of soil and water has many benefits as enumerated by Winpenny

(1991) Viz,

Avoided losses in crop yields from soil erosion, loss of soil depth and fertility, or

loss of land through gully erosion; alternative savings in fertilizer to maintain

yields on eroded soils.

Value of wood production from tree planting (timber, poles, fuelwood, forage,

fruit etc);

Value of enhanced livestock productions from restored or improved pasture,

better use of crop residues, or from fodder, trees (meat, milk, wool, dung)

20

Increased crop yields from ecological benefits of a managed mixed regime

(increased soil organic matter, more soil moisture retention, shading etc).

Farmland erosion control in Enugu state is crucial in order to avoid the

devastating consequences of soil and water degradation.

2.5 Factors Responsible for Erosion in Enugu State.

According to Onyeagocha (1980), the agent of soil erosion in Anambra and Enugu

state is water and Ude,N.C.,Uzuakpunwa,A.B.and Ezeike,G.O.I. (1980) agreed that

rainwater in any form is the most active agent causing erosion in the area but the causes

of .erosion in the old Anambra state were summarized by the form of consultants (Niger

Techno Ltd. And Technical International General Engineering, 1974) as concentrated run

off water within lithological units consisting of sands and sand-stone bed rocks covered

by a thick porous weathered layer, the disappearance of rain forest vegetations and civil

anthropogenic activities. Besides, these causative factors, other factors that play

significant role in soil erosion in Enugu and Anambra include topography (relif \slope),

climate and surface material (Ofomata 1985). Others are population density and some

.sociological life patterns such as land tenure system and local belief system of the

people.

Anthropogenic activities which either initiate or aggravate soil erosion in the

study area include poor road construction, indiscriminate house construction across

natural drainage routes, quarrying of sand and gravels, bush burning, indiscriminate tree

felling and poor farming techniques. Urbanisation, industrialization, unplanned location

of borrow sites and poor sanitary disposal measures also render the soil prone to soil

21

erosion (Akamigbo, 1988). Human erosion action is made manifest on the earth‘s surface

through his agricultural activities, especially through the clearing of the original

vegetation or the periodic forest regrowth. These activities in southeastern Nigeria

particularly in Enugu state have largely succeeded in replacing the former rain forest by

grassland (.derived) savannas. When man destroy the vegetation, it affects the soil very

adversely because, first, it interrupts the building up of organic matter, and secondly it

accelerates the decomposition of the humus inherited from the former vegetal cover.

This humus affects both the permeability of the soil and the rate at which water infiltrates

through it. Indeed it is thought that the humus content of soils explains in part the

generalized nature of the runoff in an area. (Ofomata, 1988)

Erosion is as old as agriculture. It is a process which is continually transforming

the earth‘s surface and it is initiated by natural forces and intensified by human activity

which has been significant in the recent period as man began to step up the exploitation

of natural resources (Amechi, 1997 and Edward, 1993). Whitlow,(1987) and

Aneke,Obuji,and Nwafor,(1982), opined that erosion is due to. growing pressure on the

land from human and livestock populations while Gowon (1981) stated that erosion in

Nigeria is .caused by careless use of land for agriculture and other purposes.The common

farming practices that lead to soil erosion are; the ploughing of land up and down the

slope, clearing a piece of land by burring, continuous farming and cropping,

deforestation of forest especially on the higher slopes and the overgrazing of grasslands

especially by goats and sheep (Middleton, (1990) and Lal (1990). As long as vegetation

remains, there can be little if any erosion, because the roots of the plants bind the soil

particles together and the vegetation itself protects the soil from the action of wind and

22

rain (Pitman, 1987).Lal (1990) noted that rainfall leads to leaching and runoff which is

the central agent in soil erosion system. When runoff is concentrated, it gives rise to gully

erosion and when it is unconcentrated it gives rise to sheet erosion.

According to Nigeria Institute of Social and Economic Research (NISER, 1988),

the choice crop that are labour intensive or attract human traffic may cause severe soil

erosion. For instance cashew tree (Anacardium occidentale) was introduced in some

gullied areas in the southeastern Nigeria including the Agulu-Nanka gully axis, for the

purpose of reafforestation and stabilization of the gullies. Cashew suppresses .many

undergrowths and encourages overland flow and erosion. Manual harvesting of cashew

fruits and its transport action causes soil compaction and encourages gully erosion

(Okafor, 1986).

Going by Gobin,Campling,Deekers,Poesen,and Feyen,(1999), biophysical and

participatory research methods were combined to examine factors contributing to soil

erosion at field plot, village and regional scale on the sandstone dominated Udi-Nsukka

cuesta in southeastern Nigeria. At field plot scale, the properties of seven pedons were

related to soil erodibility. Very high infiltration rates measured with a double ring

infiltrometer and permeameter, were not in accordance to reported runoff and soil loss.

The effect of groundcover and canopy height was incorporated into rainfall erosivity for

plots under cashew, oil palm dominated forest and secondary natural vegetation.

Cropping systems and field management practices were compared for different positions

along a toposequence transversing the plateau and escarpment of the Udi-Nsukka cuesta.

Soil loss, calculated by a modified version of the universal soil loss equation, was 10 to

100 times higher on escarpment than on plateau plots. According to Gobin

23

Campling,Deekers,Poesen,and Feyen (1999), Ravine and gully formations seemed

influenced by a combination of infrastructure, geohydrology, topography, vegetation and

land use.

The relationship between climate and soil erosion is fairly well known and for

south eastern Nigeria, especially Enugu state, rainfall and soil type constitutes the

dominant sub-factor. In the environment of south-eastern Nigeria, the rains come in the

form of intensive, violent showers of short duration, especially at the beginning and end

of rainy season. The erosive capacity of raindrops seems to result from three factors, the

amount and intensity of rainfall, the diameter of the drops and the velocity of the drops as

they strike the soil. Rainfall gives rise to runoff which is the central agent in the soil

erosion system and the nature of the concentration of the runoff leads to sheet and gully

erosion as the case may be (Ofomata, 1985,1988).The nature of surface materials

influence the rate of infiltration and thereby, of slumping and/ or sliding. Surface

configuration (relief/ slope) aids runoff, sheet erosion and gullying. Sheet erosion is

expected to be more common over fairly uniform and gentle slope, while gullying is

expected to be more characteristic of stepper slopes (Akamigbo(1999) and Ofomata

(1988).

In spite of the important role of the physical factors discussed so far, there can be

no doubt that almost unique dimension which soil erosion has attained in south eastern

Nigeria is related in very direct way to the lithological composition of the soils of the

area. This derives from their parent materials which are mainly soft sandstone formations

of cretaceous and tertiary age. Under the intensive chemical action resulting from the

high temperature and humidity conditions, of the area, these sandstone, mostly false-

24

bedded and with a high Iron content, weather down to what are generally referred to as

―red earths‖. Owing to the intensity of the chemical weathering, the red earths give rise to

soils which show a conspicuous absence of pebbles. Nonetheless, the predominant

component of the soils is sand, especially medium, grained sand (0.2 t0 0.5mm)

(Ofomata, 1988).

2.6 Classification of Soil Erosion

Soil erosion in south-eastern Nigeria can be classified into two major categories;

physical (geological or natural) and anthropogenic (human or accelerated) (Ofomata,

1988). The type of geology, soil, topography and climate of Enugu state predispose the

physical setting of the state to erosion of all types. Sheet erosion and gully erosion are

most devastating and prevalent (Akamigbo, 1988).

Several types of erosion exist in the study area. They include;

A. Natural erosion: Erosion is considered to be natural when the earths surface is being

removed by water, ice or natural agents under natural environmental conditions of

climate, vegetation and so on, undisturbed by man. This is synonymous with geologic

erosion, and its effect is not disastrous (Akamigbo 1986and 1998).According to

Chude(2005), natural erosion takes place all the time and is part of the natural process in

the formation of the landscape. This type of erosion is not a problem in agriculture

because as the soil is removed from a spot, some soil is being formed on the same spot.

B. Normal erosion: This is the gradual erosion of land used by man which does not

greatly exceed natural erosion. When we farm, it is the purpose of good soil conservation

25

and management that the erosion that occurs in the farm land would not exceed normal

erosion. The loss here is very minimal (Akamigbo, 1986and 1998).

C. Accelerated erosion: This is the erosion much more rapid than normal natural

geological erosion. This is primarily as a result of the influence of the activities of man

or, in some cases, of animals and other factors (Akamigbo ibid and ibid). Man, made

erosion is the type of erosion which the quantity of soil lost and the rate of soil loss is far

higher than the natural erosion. It is induced by human activities such as deforestation,

bush burning, cutting of hills, harvesting of stones and sand etc and is therefore referred

to as anthropogenic (Chude, 2005).

D Splash Erosion: This is the process of the detachment of soil particles by raindrops.

This occurs when rain-drops hit on an exposed soil surface free from vegetative cover

and the surface is wet. On some soils, a very heavy rain can cause a soil particle to rise or

jump as high as 2ft above the ground and move up to 5ft horizontally. In terms of

quantity, as much as 224t/ha can be splashed up by a very heavy rainfall. Splash erosion

even on cropped land is evidenced by the presence of soil particles on the underside of

green vegetables. Splash erosion is directly related to the raindrop size and the type of the

soil structure. The defaced particles are removed by surface runoff as sheet erosion

(Akamigbo 1986 and 1998).

E. Sheet Erosion: This is the removal of a fairly, uniform layer of soil from the land

surface by runoff water, and other agents. This type of erosion is most dangerous for our

agricultural lands as it carries away the humus top soil. It often goes on unnoticed due to

its gradual, constant and uniform action. It renders the soil infertile and its disastrous

26

influence lies in the fact that it is not easily perceptible by the farmer. It may finally result

in a complete removal of the arable parts of the top soil. Through this action of sheet

erosion, the topsoil is gradually swept clear of its finer elements and plant nutrients, and

only coarse, infertile materials are left behind (Akamigbo 1986 and 1998 and Chude,

2005).

UNEP (2008), opined that sheet erosion is a phenomenon whereby a large area of

surface soil is lost by almost even blanksheet flows of surface or mear surface water.

Sheet erosion occurs nation wide, but it is last perceived because of its ―deceitful‖ slow

progress. It slowly removes the surface soil layers by rainfall runoff down slopes,

producing a devastating effect on agriculture.

F. Rill Erosion: This is an erosion process in which numerous small channels of only

several centimetres in depth are formed. It occurs mainly on recently cultivated areas

after a rain event. Rill erosion occurs when soil is removed by water from little streamlets

that run through land with poor surface draining. Rills can often be found in between crop

rows. Although its effects can be easily removed by tillage, it is the most often

overlooked and if it is not filled up, it could develop to gully erosion. Farmers can easily

handle it (Akamigbo 1998)

G. Gully Erosion: This is an erosion process whereby water accumulates in narrow

channels or rills or crevices and, over short periods, removes the soil from this channel to

considerable depths ranging from 30 to 60 centimetres to as much as 23 to 30 meters or

more. Gully erosion unlike sheet erosions is more obvious as it makes a remarkable

impression on the surface of the earth. The physical loss of the land is visibly manifested.

27

Gullies can grow in both up hill and downhill directions. A heavy rainfall can enlarge a

small rill into a big gully overnight. Gully erosion is infact another term for accelerated

soil erosion and once it is formed it difficult to stop it from growing and it is very

expensive to rehabilitate the land. The process, in most cases, is related to the activities of

man, especially those connected with the destruction of vegetation cover (Akamigbo`

1986, 1998, Chude,2005``).

Gully erosion, in contrast to sheet erosion is very obvious because of it disastrous

nature and rapid progress. It is particularly severe in Abia, Imo, Anambra, Enugu, Ondo,

Edo, Ebonyi, Kogi, Adamawa, Delta, Jigawa and Gombe States. In the southeast,

Anambra and Enugu States alone have over 500 active gully complexes, with some

extending over 100 metres long, 20 metres wide and 15 metres deep (UNEP, 2008.)

H. Streambank Erosion: While sheet, rill and gully erosion are active only during or

immediately after rainfall, erosion along the river banks occurs even during and between

rainfall. Impact on surrounding arable soil is remarkable since alluvial soils damaged by

stream bank erosion are usually the more fertile soils (Akamigbo, 1998).

I. Wind Erosion: This is the movement of soil particles by the wind. The particles may

be as fine as sand, which can be moved by drifting at or close to the ground. There is

considerable wind erosion in West African dry tropical Zone where annual rainfall is

below 600mm, the dry season lasts more than six months, and steppe-type vegetation

leaves large stretches of bare soil. It can also develop else where when the soil is being

prepared and large amounts of surface matter are crushed fine. In the areas of Nigeria

which are most affected, wind erosion is most active during the dry season and in the

28

early part of the raining season when the vegetation cover on the landscape is less (Ologe,

1986 and Roose, 1996)

According to Ologe (1986), indicators of wind erosion in the field include;

(i) Occurrence of dust haze: the dust- laden wind called the harmatan cover the

whole of Nigeria for long and short periods during the dry season. The dust

commonly settles on all exposed objects, including vegetations and ground surface.

(ii) Presence of drifting sand; In areas covered by sands and sandy soils, much

blowing of sand is often seen where the protective cover of vegetation has been

removed. This is common between the harvest and the beginning of the raining

season. The drifting sand may overwhelm, young crops, pile up against obstructions,

such as trees and tufts of grass or obstruct roads.

(iii) Occurrence of deflation hollows: These may be quite small measuring a fraction

of a square metre in area, or they may be several square metres in area. They are

typically surrounded by sharp edges which may still retain their cover of grass

vegetation.

Chude (2005), opined that wind erosions occurs when poorly covered soil is exposed to

winds higher than about 20km/hr. soil loss by wind erosion increases rapidly above the

normal wind level. Fine sand seem to be the most easily moved soil fraction relative to

sand and dry particles. He further stated that the process of wind erosion is as follows; a.

Wind abrasion detaches tiny soil particles. b. Soil particles begin pilling and sliding (soil

creep). c. Tiny particles are carried upward and transported to other places.

29

Ofomata (1988), further classified erosion into two broad subheadings of Actual

erosion and Potential erosion. He stated that the importance of this approach is to

ensure that while we engage in activities aimed at dealing with the existing forms of

erosion, we do not lose sight of the great potentialities of the problem that could empty

any moment under inadequate management strategies. Actual erosion refers to the

different types of erosion on ground while potential erosion is the erosion that occur as

result of the susceptibility of the area to erosion of varying types and degrees.

Actual Erosion:

Fig 3 is the outline map of soil erosion and shows the general state of actual

erosion in south; eastern Nigeria, particularly Enugu state. Two broad types of erosion

are represented on the figure- gully and sheet erosion. The figure also reveals that sheet

erosion is the most widespread type of erosion in the area, the figure also reveals that

erosion in the areas is due mainly to the action of running water. The typology of erosion

outlined above reflects the manner in which this running water, especially its rainwater

run off component, is organized over space. Gully results where running water is

concentrated whereas unconcentrated run off leads to sheet erosion (Ofomata, 1988).

Potential Erosion:

A potential erosion map of the area is embodied in fig 4. The map reveals that all

parts of the area are susceptible to erosion of varying types and degrees. Generally, two

categories of susceptility to erosion could be identified: high susceptibility and moderate

susceptibility. The map is adapted and modified from a preliminary ―map of Nigeria

30

showing erosion susceptibility‖ produced by the Geological survey of Nigeria as GSN

2215 (Ofomata, 1988).

From the map it could be observed that Enugu state is susceptible to various erosion

types and degree (Ofomata 1988).

2.7 Erosion Control

Chude (2005) stated that if one wants to stop water erosion, he or she should have

the following in mind:

a. Reduce the force of rain impact: That is to protect the soil against direct force of

rain.

b. Improvement of soil stability: That is to improve the ability of soil structure to

resist deformation/disruption by rain impact.

c. Reduce the amount of water causing runoff by allowing more water to infiltrate

into the soil.

d. Reduce the speed (velocity) of flood water,

Erosion control is indispensable in view of the expanding economic activity of

society and the endavour to use natural resources purposefully and economically. The

objective of erosion control is to protect the two valuable natural resources (soil and

water) and to prevent the occurrence of the unfavourable consequence which

deterioration could have for various branches of the national economy which are

agriculture, water management and human environment (Middleton 1990).

31

The method of erosion control measures to be adopted depends on the type of erosion

and there are two type or control; preventive control measures and curative control

measures. The prevention of erosion has always been a much easier, effective and

cheaper task than undertaking curative measures of eroded areas which is more

expensive. Preventive measures involve the use of conservation farming or cultural

practices that minimize raindrop impact, increase or enhance structural stability of the

soil and improve the water intake or infiltration. The curative measures involve

management of surplus water or overland flow for its safe disposal at low velocities

(Abarikwu 1988) , Akamigbo (1998), Ofomata (1982) and lal (1990). According to

Abarikwu (1988), capability classification of the land is an important feature of

conservation farming and conservation practices such as terracing, strip cropping, contour

strip cropping, crop rotation, mulching, minimum tillages, irrigation and drainage are

used depending on the land and the soil.

Erosion can also be controlled either by agronomic measures or soil management

measures or mechanical methods. A range of techniques is available and the decision on

which to adopt depends on whether the objective is to reduce the velocity of runoff,

increase surface water storage capacity or safely dispose of excess water. Mechanical

method are normally employed in conjunction with agronomic measure. Mechanical field

particle are used to control the movement of water over the soil surface. Agronomic

measure for erosion control are those concerned with the utilization of vegetation and

crop to provide cover on the surface to minimise and dissipate erosive forces (Akamigbo

1998, and Middleton 1990) .Akamigbo (1986) opined that erosion control can be carried

out in two broad measures, biological and engineering measures. He stated that biological

32

measures are largely preventive and consequently cheaper. According him, engineering

measures are adopted especially when the erosion problem is already initiated and in

advanced stages and are much more expensive to apply.

Agricultural and forestry measures used for erosion control exist in the correct

location of cultures, a well designed layout of plots and communication system, correct

cultivation of field and forest soils and use of the preventive effective vegetative cover

(Lal, 1982). Use of vegetation for soil conservation involves the use of agricultural and

forest plants. The methods include soil conservation, crop rotation, strip cropping, grass

land farming, protective forest belt, alley cropping agroforestry and afforestation (Senft

1994).

Effects of Agroforestry practices on soil conservation:-

Agroforestry practices encompass an entire spectrum of land use systems in

which woody perennials are deliberately combined with agricultural crops and or animals

in some spatial or temporal arrangement(Lundgren and Raintree, (1982).The presence of

woody perennials in agroforestry systems may effect several bio-physical and bio-

chemical processes that determine the health of the soil substrate (Nair, 1993). The less

disputed of the effects of trees on soil include amelioration of erosion primarily through

surface litter cover and under story vegetation maintenance or increase of organic matter

and diversity, through continuous degeneration of roots and decomposition of litter,

nitrogen fixation, enhancement of physical properties such as soil structure, porosity, and

moisture retention due to the extensive roots systems and the canopy cover, and

enhanced efficiency of nutrient use because the tree root system can intercept, absorb and

33

recycle nutrients in the soil that would otherwise be lost through leaching (Subhrendu and

Evan Mercer, 1996 and Sanchez, 1987).

Ojanuga (1986), advises that combating soil erosion in Nigeria requires a

judicious development and management of the land, based on sound scientists principles.

He continued by opining that it calls for judicious land use planning at national, state,

local and more importantly at individual farm level. Morgan (1980),also observed that the

impact of the soil erosion on the environment is not of primary concern to the individual

farmers alone, it is the responsibility of the national or regional authorities advised by

experts dealing with soil conservation.Akamigbo (1986), proposed the adoption of target

erosion control methods. According to him, certain areas are more prone to water erosion

than others. It is not feasible to move towns from their ancestral homes to other

ecological zones. He therefore advocated that such highly susceptible and already

devastated areas of Agulu/Nanka must form target areas for the federal government.

Measure to combat the soil erosion process and thereby save farmlands,

employment and income have for long been implemented by the federal, state and local

governments. The strategies were preventive as well as curative and include the Udi-

Forest consolidation Scheme established in 1922 by the former British colonial office, the

Agulu soil conservation scheme established in 1945 and the Ronasco Anti-Erosion

project executed between 1980-1984 in six designated erosion sites. These and many

other Anti-erosion Schemes were designed and implemented by government officials

without any consultations with the local people (Floyd, 1969).

34

Limited information obtained from scattered sources, however indicate that the

native people of South-eastern Nigeria apply a wide range of traditional techniques to

conserve soil control erosion and prevent soil degradation. These techniques which range

from the agronomic and agroforestry to enthno-engineering (mechanical) aim at two

major results; to prevent as much runoff as possible from reaching the gullies and to

reduce the extent of bare soils susceptible to sheet and rill processes (Ofomata, 1982).

Reference could be made to the popular use of ―mkpuruji‖ (Local mounding) ―ekpe‖

(contour bunds), ―Ogwugwo‖ (pitting systems) and ―Igba‖ (ridging systems) as anti

erosion practices in many parts of the region. These practices are sustained by a

communal works scheme under which household participation is mandatory (Lemchi,

1992).

Eventhough evidence shows that these traditional techniques are curtailing further

gullying, reducing sheet wash and managing run-off, they remain largely understudied,

unexplored and neglected (Reiji, 1990). Despite the fact that these indigenous anti-

erosion techniques provide indisputable starting point for a sustainable environmental

project in the area, local environment knowledge, skills, experiences and expertise cannot

be dismissed as irrelevant in the design and implementation of anti-erosion projects.

Rather, for them to be successful and sustainable, such projects would rely on indigenous

expertise and skill during planning, execution and evaluation (Lemchi 1992). The

environmental researchers and conversationalist have been drawing attention of policy

makers to the approach weakness of the top-down approach to soil conservation

(Reiji.1990, O‘ Riordan, 1990, Showers and Malahcela, 1990).

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The challenges facing erosion researcher is to articulate, in collaboration with the

local peoples understanding of the technical, agronomic and organisational dimensions of

traditional anti-erosion compain. Therefore, there indigenous systems of anti-erosion

management could be built upon and improved for long term sustenance (Lemchi;

1992).We must strive to protect and enhance the nutrient cycle and to enhance soil

fertility. This means promoting and implementing sustainable technologies and

approaches like alley farming and agroforestry, while eliminating burning and other

wasteful practices. It also means supporting reforestation programs and community tree

planting efforts and letting land rest once every three or four years (Tacio, 2007).

It is our task to conserve the productive capacity of our soils. The wealth and

culture of any country depends upon its topsoil. Once this is gone no agricultural

manipulation will bring it back to full production. Improved methods may increase the

productive capacity of a worn out soil, but the same methods would have resulted in

much larger yields if the soil had not been degraded in the first place. Such soil

restoration becomes necessary in many cases, but our aim should be the conservation and

increase of soil productivity for present and future generations of Nigeria (Ali, 2006).

2.8 Problems and Effects of Soil Erosion.

According to Green (1982), the question of the proper use of agricultural land

touches on the livelihood of every citizen for it is an essential support of human life not

only in relation to food supply, but also for the production of fibre and shelter.

Erosion affect a number of branches of the natural economy and has a far

reaching effect on the social and cultural lives as well as health of the helpless inhabitants

of the affected areas. Agriculture is that branch of the national economy which is most

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affected by the erosion processes. Millions of hectares of farmland are being affected

these days by soil erosion.

Akamigbo (1998) reported that erosion, as an environment hazard has numerous

adverse effects on the lives and livelihood of people and that it generally results in a

degradation of the environment, and reduction in the land area that is available for

habitation, agriculture, industry, recreation, road construction and other uses. Topsoil

were lost to soil erosion, exposing the gravel layer and the less productive subsoil (Obi

and Asiegbu (1980) and Lal, 1979).Soil erosion is one of the problems menacing

agricultural soil and it results in degradation of soil physical characteristic such as

infiltration rate, soil structure and crusting. It also decreases the efficient use of fertilizers

by increasing the nutrient losses. Woomer and Muchena (1995) opined that soil erosion is

chronic depletion of the soil.Currently the biggest threat to meeting future agricultural

needs comes from soil erosion degradation which according to Douglas (1994) have the

following far- reaching consequence;

* Soil and vegetation: declining soil productivity means less vegetation cover to soil,

less return of organic matter and less biological and nutrient activity.

* Yield: as soil productivity declines, the useful economic yields from crops and pastures

will decline,

* Return to the farmers: declining productivity means that direct returns are reduced,

cost of production increased and sustainability of return is less.

Furthermore erosion also leads to pollution and blocking of water ways, loss and

destruction of social centres and social amenities (Ezeebube, 1989, Akamigbo,1999).

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FAO (1979) stated that 2.5m of top soil layer was lost in a matter of hours to days in

heavy storm or runoff where the soils were saturated. Soil erosion affects farming in

detrimental ways. Physical damage is the most visible form of soil loss, and most likely

to be remedied (Seafriends,2001).

Akamigbo (1984) reported that appreciable reduction in colloids and clays could

result from vertical erosion with a consequent reduction in fertility. FAO(1965) observed

that losses through water erosion were usually the most fatal, containing the plant

nutrient, humus and the fertilizer that the farmer had applied. Jungerius (1964) reported

that organic matter content was low in the erosion sites of soils of eastern Nigeria

particularly in Enugu state. Tropical soils have a higher concentration of nutrients in the

top soil as compared with temperate soils and this feature was greatest in the highly

weathered soils of intrinsically low fertility (Young, 1989).

Erosion may adversely affect the functioning of the trees themselves in an

agroforesty systems. Habte and Eleswaity (1986) noted in Hawii that stimulated erosion

removal of 7.5 to 37.5cm topsoil greatly reduced nodulation, nitrogenase activity,

nutrient uptake and growth of Sesbania gradifora. Dike (1995), opined that erosion

reduces yield and productivity of crop and soil through the various ways; loss of plant

avaiblewater, loss of plant nutrient, degradation of soil structure, non-uniform removal of

soil within a field and affecting timing of farming operations. Apart from the effects of

erosion on agriculture, rivers are filling rapidly with sediments of soil particles which

threatens both domestic and irrigation water supply (Cooke,,Doorkamp,Brunsden, and

Jones,(1995) and Mumel,(1995).

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The transportation of soil particles by wind erosion had adverse effects on whole

areas. Debris and soil removed by wind erosion are often deposited on vegetation and

they damage buildings, communication, canals, and ditches (Middleton, 1986). Skidmore

(1986) stated that blowing soil fills roads and ditches, reduces seedling survival and

growth, lowers the marketability of vegetable crops like asparagus, green beans, lettuce,

and okra, increases the susceptibility of plants to diseases and contributes to transmission

of some plant pathogens. Leather, (1981) reported that soil particles carried by wind

pollute the atmosphere causing health hazards to people and animals who suffer from

disease of the respiratory track and eye inflammation.Pye (1987) proved that about 310

tons of dust particles are in 1km3 of air in a dust storm and dust pollution obscures

visibility and causes antomobile and aircraft accidents.

Another grave danger of erosion to the society is the transportation of chemical

substances which infiltrates surface and underground water and limits the use of water

resource (Goudie, 1983). The fragment sources of these chemicals are chemical

fertilizers, and the different pesticides, herbicides and fungicides applied in large

quantities in agriculture as well as industrial and agricultural wastes discharged on or into

the soil. Also large scale atmospheric dust concentrations affects local meteorological

processes and may over long period lead to reduced rainfall (Middleton, 1989).

Deposition of chemicals on the sea, river, streams, oceans affects biological

balance in streams, rivers and other bodies of water leading to eutrophication (excess

nutrient) phenomenon in streams, rivers and lakes (Svatos,1975). Mellanby (1967),

noticed that polluted water especially by pesticides is a health hazard to man not only

directly through contact but also through food chain. Other problems of erosion as

39

reported by Odoh (1995) and Akamigbo (1999) are destruction of roads, lives, houses,

flooding and starvation As far back as 1964, 47% of the soil of Eastern Nigeria was

affected by measurable sheet erosion while 20% suffered from severe sheet erosion

(Ofomata 1976). By 1990, gullies occupied 4% of the land area of Anambra, Imo, Abia

and Enugu states and the rate of gully formation and the extension of existing ones was

still increasing (World Bank, 1990).Soil erosion causes a reduction in available farm

lands (Chude, 2005).

The world loses the equivalent of five to seven million hectares of farmland

through erosion each year. This is equivalent to the land area of Belguim and the

Netherlands combined. Soil experts says there is nothing wrong with normal soil erosion,

which in even beneficial to man, but accelerated erosion usually caused by man himself

is harmful. Studies have shown that as much as 20 percent of eroded materials end up in

rivers, reservoir, and irrigation canal and siltation also cause serious damage to coral

reefs and coastal fisheries (Tacio, 2007). Soil erosion is main agricultural externality and

a main threat for sustainability in agricultural systems, as it reduces the potential for

agricultural production. The loss of topsoil affects main‘s ability to grow food in two

ways. First, it reduces the inherent productivity of land, both through nutrient loss and

degradation of the soil‘s physical structure, second, it increases the cost of food

production to maintain the level of agricultural production in the farm (Franco and

Calatrava-leyva (2006) and Tacio, (2007). Tacio (2007), and Akamigbo (1999)

concluded that if productivity drops tow low or cost rise too high farmers will be forced

to abandon their land. In both cases, soil erosion result in a land rent loss and in

40

productive capital loss that may result in a decline in the market value of eroded land

(Franco and calatrvaa-leyra (2006) and Akamigbo, 1999).

Erosion has social and psychological impact on people‘s lives. This impact is

incalculable (Onwueme and Asiabaka, 1992). Many villagers in gully- prone area live in

constant fear of their lives and properties, not knowing whether the buildings which they

occupy today will end up in the bottom of a gully the following day. There is high degree

of personal and communal insecurity. It results in social up heaval. Erosion also induces

superstition since some people claim that gully erosion is a retribution from the gods.

Quarrels and fighting often arise as the available uneroded land is fragmented to unviable

agricultural tracts for an agricultural community (Akamigbo, 1999).

Gully erosion has had and will continue to have destructive impacts in and around

southeast of Nigeria in the absence of immediate corrective and preventive measures

(Orabuchi, 2006).

2.9 Documentation of Farmland Erosion Sites in Enugu State.

Devastating erosion sites cut across the state . some of them are listed below.

EROSION SITES IN ENUGU STATE

1, Ajali Owa water Works - Major

2, 9th

Mile by Ama on Road Leading to Eke in Ezeagu -Major

3, Agbani (Eke Market) Erosion Site

4, Akugo Ndiagu to Obuno Akpugo Erosion Site -Major

5, Ezimo Uno Erosion Site –Major

6, Obiekpo-Abor Erosion Site -Major

7, Umualor Mamu Forest Ugwuoba Erosion Site

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8, Ugwu Egbe Obollo-Afor Gully Erosion Site

Leading to Federal College of Education, Eha-Amufu -Major

9, Ugwugo- Opi Road Gully Erosion

10 Ebe Erosion Site

11, Ozalla Nkanu Erosion Site

12, Obinagu Gully Erosion Site

13 Eke Ogbaku Erosion Site

14 Ugbawka Erosion Site

15 Akegbe Ugwu Erosion Site

16 Agungwu Ugwuoba Gully Erosion Site -Major

17, Access Road to Ajali Water Workes/ Ajali Erosion Site -Major

18, Timber Shed Erosion Site

19 Agulu- Amokwe Road Erosion Site

20,Ukehe-Agukehe- Agu Umunko Erosion Site

21, Enugu-Port Harcourt Express Road Erosion Site (by Nyaba Bridge)

22, Umuokoloma-Affa -Major

23, Okwojo Ngwo/Agbaja Ngwo Erosion Site

24 Ogugu- Awgu Erosion Site

25 SEDES SPIENTIAE Oghe

26 Community Secondary School Amokwe

27 Airport-End of Run Way 26 by Niger Gas Emene Enugu

28 Obeleagu Umana Erosion Site. –Major

29 Coca Cola 9th

Mile Corner Erosion Site - Major

30 Obimo Erosion Site -Major

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31 Ugwuoba-Nidukwuenu Awa -Major

32 Eke Oghe -Major

33. Onyeama Mine (Erosion-Onitsha Expressway) -Major

34 Egede Amozalla-Affa Road Erosion Site -Major

35 Lejja Nsukka Erosion Site -Major

36 Amokwu Affa Erkosion Site Major

Source: Enugu State Ministry of Environment, (2008).

2.10 Review of Existing Farm Management Erosion Control Practices.

1. Crop Rotation: This is the method of farming in which the same piece

of land is kept under cultivation every year in such a way that the crops follow a definite

order planned in such a way as to restore nut