Spatial Variation of Soil Physical and Biological Properties under Faidherbia Albida System

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Chanda, Patience
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The University of Zambia
Faidherbia albida is a deciduous and indigenous tree species in the Fabaceae (legume family) native to much of Africa and the Arabian Peninsula to western Asia. It is used in agroforestry systems to stabilize and improve soil fertility as it is associated with nitrogen-fixing bacteria. Faidherbia albida (Del.) A.Chev. (Syn. Acacia albida Del.), is appreciated in many parts of Africa for its ability to provide shade in the hot season, good quality fodder, improve soil fertility through litter fall and nitrogen fixation. The tree has received little management and research attention over the years leading to over-exploitation by the local communities. Assessing the spatial variability of soil properties is crucial to efforts designed to introduce sustainable cropping systems. Soil properties vary spatially from a field to a larger regional scale as affected by both intrinsic (soil forming factors) and extrinsic factors (soil management practices). Therefore, knowledge of soil spatial variation is an important determinant of efficiency of farm inputs and yield, as well as in site specific farming and environmental modelling. The study was conducted to evaluate the degree of spatial variability of selected physical, chemical and biological properties under and outside the tree canopy. Spatial interpolation of soil properties was determined by using Ordinary Kriging. The results obtained indicate that soil texture (% sand, % silt and %clay) was highly variable within the sampled site. The spherical model is the best fitting model for predicting sand and microbial activity. Whilst soil reaction and organic matter were best described by both the spherical and exponential modeK^The best fit model for silt and clay was Gaussian and Exponential models respectively using the least sums of square error. The spatial distribution of soil properties provides basic and useful information relevant to soil management and agricultural production. Keywords Faidherbia albida, soil, kriging, sand, silt, clay, soil reacfion, organic matter, microbial activity
Faidherbia Albida , Faiderbia