This is the conceptual perspective of pedology and edaphologythe two main branches of soil science. Pedology is the study of soil in its natural setting.
Vast areas of the rainfed uplands in the humid and subhumid tropics currently used for traditional food crop production are dominated by these "fragile" soils.
As the clay fraction of these soils are composed mainly of kaolinite, halloysite, and oxides of Fe and Al, the soil ECEC depends mainly on the soil organic matter level, which controls nutrient absorption and release. Significant changes in soil chemical and biological properties also occur following forest or bush fallow clearing and cropping.
Soil organic matter declines sharply during the first few years under cropping and the effect is more pronounced with intensive continuous cropping.
The loss of organic matter and acidification resulted in a decrease in the effective cation exchange capacity ECEC and the loss of Ca and Mg Kang and Juo, The arbitrary application of exotic, high -input food crop production technologies on these fragile soils The classification and application potential of often leads to rapid chemical, physical, and biological degradation of the soil.
Although soil fertility problems on the LAC soils can be corrected by liming and appropriate fertilization, socioeconomic constraints often limit the application of these crop production technologies in many areas of tropical Africa.
Currently, sub-Saharan Africa's per capita and per hectare fertilizer use is very low compared with that of other regions.
There is a need to develop integrated soil fertility management systems for the region based on better utilization of local nutrient sources. Such systems should be supplemented with external inputs wherever that is feasible and affordable. For sustained crop production in addition to adequate supply of plant nutrients, the LAC soils also require continuous addition of organic matter.
Integrated soil fertility management for LAC soils can be achieved by various methods including: Use of low levels of chemical inputs in combination with fallowing and agroforestry systems has shown varying degrees of success.
Fallowing and addition of organic mulches may correct chemical soil degradation resulting from continuous cultivation; at the same time, it may also increase efficiency of fertilizer use. Crop residue management and seed bed preparation methods can play an important role in sustaining the productivity of these soils for crop production.
The presence of adequate amounts of mulch cover helps maintain high soil nutrient status and high biological activity. Mulch also protects the soil against high temperatures, soil erosion, and run-off, thereby preventing the breakdown of soil structure and the resultant soil compaction and decreased permeability.
Furthermore, mulching increases soil moisture retention and reduces runoff and soil erosion Lal, ; Kang and Juo, Results of long-term field experiments carried out on Alfisols have also shown that with judicious fertilizer use and crop rotation, high and sustained crop yields can be obtained Kang and Juo, However, little information is available on the soil requirements for growing the MPTs.
As with crops, the capacities of MPTs for biomass production and nutrient recycling are affected by soil and climatic conditions.
Additions of nutrients may be needed for good growth of MPTs. MPTs for alley farming such as Leucaena leucocephala and Gliricidia sepium do well on non-acid or slightly acid Alfisols.
Both species perform poorly on acid soils.
A great number of systems of land classification are in use, varying mainly according to the purpose for which the land is classified.
Land may be classified according to its present land use, its suitability for a specific crop under the existing forms of management, its capability for producing crops or combinations of crops under optimum management, or its suitability for non-agricultural types of land use.
A good knowledge of the land capability and suitability combined with good understanding of the soil characteristics and management aspects are the keys to more productive and sustainable agriculture. The purpose of land capability classification systems is to study and record all data relevant to finding the combination of agricultural and conservation measures which would permit the most intensive and appropriate agricultural use of the land without undue danger of soil degradation.
The USDA land classification system is interpretative, using the USDA soil survey map as a basis and classifying the individual soil map units in groups that have similar management requirements.
At the highest of categorization, eight soil classes are distinguished, namely: Class I soils have few limitations restricting their use.application allows a user to either take a picture or upload an existing picture of a leaf and the mobile application displays a listing of potential classifications with percent likelihoods for each of the top three results and an image of each given classification.
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