Assessing The Physical And Chemical Properties Of Soil In Nigeria

Project and Seminar Material for Soil Science

Abstract

This study was conducted to evaluate the physical and chemical properties of some selected soils of rain forest zones in Delta State; Latitude 50 and 60 and 30’ North and longitude 50 and 60, 45’ east. Hence, representative soil samples were obtained from four locations viz: Abraka, Sapele, Mosogar, Aghalokpe (Rainforest zone) at 0-15cm and 15 -30cm depths. These were analyzed for their physical and chemical properties. The soils studied were mainly sand and loamy sand, with sandy texture predominating. The soils had a pH range of 4.72 to 6.52 at the surface, and were marginal inorganic carbon, total nitrogen, exchangeable Ca, Mg, and ECEC. Zinc, Fe, Cu and Mn contents were found to be adequate based on established critical levels for the various nutrients. Potassium levels were found to be deficient in the soils.

Table of Content

Chapter One

1.0 Introduction

1.1 Background to the Study
1.2 Statement of the Problem
1.3 Aim and Objectives
1.4 Research Question
1.5 Significance of the Study
1.6 Scope of Study
1.7 Definition of Terms
1.8 Organisation of the Study

Chapter Two

2.0 Literature Review

2.1 Conceptual Review
2.2 Organic Matter and Soil Erosion
2.3 Organic Matter and Soil Physical Conditions
2.4 Structure of Soil Aggregates
2.5 Chemistry of Soil Aggregation
2.6 Soil and Land Use in Nigeria
2.7 Effects of Land Use on Soil Properties and Soil Erodibility
2.7.1 Physical Properties
2.7.2 Chemical Properties
2.8 Soil Degradation
2.8.1 Causes of Land/Soil Degradation
2.8.2 Effects on Land Degradation
2.8.3 Monitoring of Land Degradation

Chapter Three

3.0 Materials and Methods

3.1 Study Area
3.2 Soil Evaluation
3.3 Soil Preparation and Analytical Methods
3.4 Soil Analysis
3.5 Statistical Analysis

Chapter Four

4.0 Results and Discussion

4.1 Result
4.2 Discussion of Findings

Chapter Five

5.0 Summary, Conclusion and Recommendation

5.1 Summary
5.2 Conclusion
5.3 Recommendation
References

Chapter One

1.0 Introduction

1.1 Background to the Study

Through the ages the relationship of man to the soil has been of primary importance to his survival. It has been observed that where soil is lost, civilization goes with it. Today, soil is as essential for the production of food, shelter, fibre and fuel as it was in the Neolithic age. Loss of agricultural soils through soil degradation has been and remains a major conservation problem (Adu, 1972). Degradation of agricultural soils usually begins with the deterioration of the vegetative cover due to over grazing, wood-cutting, improper cultivation and bush fire (Weert and Lenselink, 1972). These lead to accelerated water erosion, soil compaction, increase in bulk density, decrease in porosity and reduction in infiltration rate, surface crusting and loss of soil fertility. Structural deterioration through lack of organic matter is a danger to productivity of agricultural soils (Hubert, 1983).

The methods of combating soil degradation include contour ploughing or a system of contour ridging, cover cropping, manuring and mulching, which tend to improve the soil structure. Another method is to practise shifting cultivation. The chief problem with shifting cultivation, however, is that the demand for higher food production to feed the increasing population is pressurising many farmers to shorten or even eliminate the long fallow period. Without the full period of regeneration, the land does not recover from the loss of nutrients, erosion and deterioration of soil structure resulting from continuous cultivation. The consequence of shortening the fallow period, therefore, is a decrease in soil productivity. A permanent destruction of the soil can even occur (Hubert, 1983).

It is important to note that due to the scarcity of food it is not easy to leave the land to fallow for the 25-30 years as suggested by Gourou (1965) or 6-8 years as proposed by Morgan and Pugh (1969). Therefore, as a means of sustaining soil productivity, farming systems research has focused on agroforestry which is gaining widespread popularity in the tropics. The concept of alley cropping i.e. a cropping system where arable crops are grown in the interspace (or alleys) between rows of planted trees or woody shrubs (pruned periodically to prevent shading and to provide green manure and/or mulch to the arable crop – Nair, 1984), is possibly the most versatile, effective and widely adaptable practice in soil conservation farming.

Several advantages are attributed to alley cropping. These include sustained use of land through recycling of high amounts of organic matter, maintenance of a humid micro-climate, reduction in runoff, erosion and siltation, and regulation of stream flow which affords a means of combating desertification. This approach, is therefore based on “self-maintenance” (Bene et al., 1977; Nair, 1984). Thus, the system and the management practices associated with them should strive to attain maximum efficiency of inputs, while maintaining the productivity of the soil in a sustainable manner, with a strong bias towards resource conservation.

The integration of trees as a modification for improving shifting cultivation in Africa started in the 1950s (Pereira et al., 1958; Jurion and Henry, 1969). Agroforestry systems have been also found useful for cultivating steeplands in densely populated regions of the Philippines, Northern India and Indonesia (Lai, 1989) . In Nigeria, the need to plant trees (Woodlots) to check the spread of the desert dates back to 1937 (Benneh et al., 1990). In 1986 the Ministry of Agriculture also established a unit to promote the objectives of agroforestry in the country. Elsewhere in Africa, studies have centred on the effects of alley cropping on yield and nutrient availability (Chijioke, 1980; Nair, 1984). In Nigeria, however, more work remains to be done especially on soil physical properties. It would, therefore, be of interest to study the effects of alley cropping on some selected soil physical properties in Nigeriaian soils.
Since organic matter plays an important role in the chemical and physical properties of soils e.g. improved soil fertility, cation exchange capacity, good soil structure, and soil aggregate stability among others, it would be of interest to study soils under the system of alley cropping with a view to comparing the changes in some soil properties with those of pure wood-stands. It is anticipated that this study would give the much needed quantitative information on the measured soil physical and chemical properties.

1.2 Statement of the Problem

Nature of parent material has been found to influence development and characteristics of soils. The ability of a soil to support plant growth depends on its physical and biological properties which have been found to play significant roles in crop production. A soil that supplies adequate nutrients needed by plants with favorable soil pH will produce better crops quality and yield if other conditions of growth such as biological and physical properties of the soil are favorable. The quality of soils does not depend on its ability to supply adequate nutrients alone but the nutrients must be in the right proportion as needed by plants [1]. The declining soil fertility have been reported as a major limitation to increasing yields, and a threat to sustainability of crops [2] is the need to take the inventory of their nutrient status in the soils.

1.3 Aim and Objectives

The broad objective of the study was to evaluate the physical and chemical properties of some selected soils in rain forest zone of Delta State. The specific objectives were to;

Identify the physical properties of some selected soils in rain forest zone of Delta State
Identify the chemical properties of some selected soils in rain forest zone of Delta State
Examine the micro nutrient of some selected soils in rain forest zone of Delta State

1.4 Research Question

The following research questions are formulated to guide this research:

What are the physical properties of some selected soils in rain forest zone of Delta State?
What are the chemical properties of some selected soils in rain forest zone of Delta State?
What is the micro nutrient content of some selected soils in rain forest zone of Delta State?

1.5 Significance of the Study

A good knowledge of the variations of soil physical – chemical properties as it relates to micronutrient status is essential for good land evaluation which is a pre-requisite for sound land use planning. Moreover, information on the profile distribution of these elements in arable crop growing soils will provide the basis for making informed decision with respect to fertilization and other soil management practices. The findings of this studywill help us to know which one meets up the standard while promoting public health awareness.

1.6 Scope of Study

This study was carried out in rain forest zone of Delta State. The study was limited to assessing the physical and chemical properties of soil in Nigeria.

1.7 Definition of Terms

Physical Properties:

Refers to any characteristic that can be determined without changing the substance’s chemical identity.

Chemical Properties:

Refers to any characteristic that can be determined only by changing a substance’s molecular structure.

Soil:

Is the loose surface material that covers most land. It consists of inorganic particles and organic matter. Soil provides the structural support to plants used in agriculture and is also their source of water and nutrients. Soils vary greatly in their chemical and physical properties.

1.8 Organisation of the Study

This research work is organized in five chapters, for easy understanding it is broken down as follows:

Chapter one kicks off with the introduction, which consists of the background of the study, statement of the problem, objectives of the study, research hypothesis, scope and significance of the study.
Chapter two begins with the conceptual framework on which the study is based, the theoretical literatures and also the empirical literature and thus the review of related literature.
Chapter three deals on the materials and methods used for the study.
Chapter four concentrate on the data collection and analysis, interpretation and presentation of finding.
Chapter five gives summary, conclusion, and recommendations made of the study.

Chapter Five

5.0 Summary, Conclusion and Recommendation

5.1 Summary

The study was carried out to assess the physical and chemical properties of soil in Nigeria. From the findings, the texture of the soils varied from sand to loamy sand. Soil samples from K Abraka, Aghalokpe and Mosogar were found to be sandy at the topsoil and subsoil. Soil samples from Sapele were found to be sandy at the surface and loamy sand at the sub-surface. pH values of various locations ranged from 4.72 in Abraka to 6.52 in Sapele, that is, from strongly acidic to slightly acidic. The percentage organic carbon values showed decrease with depth. At the surface it varied from 0.70% in Sapele to 1.73% in the soil from Abraka. Available phosphorus for all the locations ranged from 35.2mg/ kg in Sapele to 50.1mg/kg in Aghalokpe at the surface. Exchangeable potassium for all the locations ranged from 0.03 to 0.57cmol/kg in the surface and 0.10cmol to 0.25cmol/kg in subsurface. Exchangeable magnesium value ranged from 0.16 to 0.80cmol/ kg at the surface, while at the subsurface, it ranged from 0.80 to 1.92.

Zinc content ranged from 20.9mg/kg in Abraka to 46.6mg/kg in Mosogar at the surface soils and from 20.9mg/kg in Sapele to 40.3mg/kg in Mosogar at the sub-surface soils.

5.2 Conclusion

The determination of the physical and chemical properties of the rain forest zone of Delta State was the principal objective of this study. Soil analysis to determine the levels of plant nutrients in the soils was carried out. Consequently, the results from this study showed the soils of the area of study were mainly sandy loam; and that the soils of the area of study had suitable pH, marginal nitrogen, exchangeable calcium, magnesium and ECEC. The soils were sufficiently supplied with micro-nutrients; especially, zinc, lead, iron, copper and manganese. However, the soils are deficient in available phosphorus and exchangeable potassium.

5.3 Recommendation

The following recommendations were made;

It is recommended that phosphorus and exchangeable potassium should be artificially supplemented for growth and yield of crops needing higher level of these nutrients.
Soil properties most be considered for sustainable agriculture and proper land management practices that will promote the environment. Application of organic matter will be essential for most of the nitrogen and basic cation to be utilized by crops for quality productivity.