Properties and functions of organic materials in poor agricultural soil condition

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*S. Usman¹

¹Natural Resources Institute, Agriculture, Health and Environment Department, University of Greenwich at Medway, UK ME4 4TB [email protected]

SUMMARY 

One of the key goal of sound soil management is to create a healthy soil environment which may retain balance nutrient status (Omotayo and Chukwuka, 2009) by protecting the surface soil cover from unacceptable changes such that its fertility will maintained over time. Generally speaking, little information on properties and functions of most used organic materials for soil quality management in areas such as the Sudan Savannah (SS) of Kebbi State, Nigeria can be found up to the writing of this work. While organic materials protect soil against runoff, mass movement of fine soil particles and surface soil damages. Organic materials are the storehouse of all essential soil and plant nutrient in soil and they are important components of soil fertility, which are associated with a variety of other important soil physical, chemical and biological characteristics (McDonald, 2010). Therefore, to improve the standard balance of the morphological and genetic properties of the deteriorated agricultural surface and subsurface soils in the SS, it is necessary to be able to address and understand the properties and functions of organic material in single and in combination under poor agricultural soil conditions in the SS. However, in the process of addressing and understanding the properties and role of organic materials in soil, the complete management exercise was undertaken according to four principal stages. However, the main objective of this study was assessment of physical, chemical, physico-chemical properties and functions of organic material under soil quality and soil fertility management in the SS. The study would profitably lead to more sustainable and permanent soil management, soil quality and soil fertility rehabilitations for high crop yield in agriculture. 

Physically, important soil particles transformation has been exist between soils texture, structure, consistency and colour under soil quality development whereas chemically, significant amount of essential nutrients were transferred into the soil for soil fertility function. This transformation of the physical and chemical properties over different organic materials has provided a healthy and functional soil condition for proper plant growth. The concentration of percentages organic matter and nitrogen and total exchangeable base saturation were 0.85 to 2.08%, 0.04 to 0.58% and 9.11 to 16.2 whereas the available phosphorus and potassium are 15.7 to 50.8 and 126.6 to 182.8 for all the soil strata respectively.

Similarly, individual soil texture (sand, silt, clay) tends to improves as decomposition of organic materials increased in soil strata. This improvement of soil texture is likely associated with textural properties of different organic materials such as cement, gravely, coarser and fine. Interestingly, the percentages organic matter and clay content were increased as opposed to most of the textural classes and organic matter content observed under similar soils in the SS. 

It is therefore assumed that the transformation observed in the aspect of soil physical properties was due to added organic materials in soil. Because as organic materials slowly decomposed in soil, they colour the surface soil, maintain the soil strength, increase soil resilience (ability of soil to return to its initial state after disturbances), soil aggregation and aggregate stability; thereby transforming soil texture into stable, suitable and good textural quality classes for wide range of crop production. Physically, the high aggregate stability and surface soil colour quality are high under the soil strata 01, 02, 03, 04 and 12 than in soil strata 05, 06, 07, 08, 09, 10 and 11. 

The physical, chemical and physico-chemical properties of different organic materials were separately assessed and analysed. These different organic materials were used under soil quality and soil fertility rehabilitation. Data presented indicated that each individual organic material have unique physical, chemical and physico-chemical properties. Characteristically, all the organic materials contained proto-chemical, sulphurous, and gaseous compounds as well as nitrogen, phosphorus, potassium, calcium and magnesium. These properties have reflected various processes and interactions of physical, chemical and biophysical properties of soil under soil quality and soil fertility rehabilitations. The compounds have also interacted with each other in soil and their interaction improved soil texture, soil structure, soil consistency, soil colour and soil organic matter. Although, further assessments are still needed under each individual organic material, however, it is possible that the outcome of this study will help in the understanding the physical and chemical aspect of organic materials under soil quality and soil fertility management practices in agriculture. The use of organic materials in soil management will be a good way to improve and maintain soil quality and soil fertility rehabilitation under agricultural production.