ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 68 Number 2
Improving site-specific fertilizer distribution in peasant agriculture in Zimbabwe
A study was undertaken to determine the ability of a sampling survey of plant and soil material from Zimbabwe farmers' fields to characterize and delineate, at the village level, geographic areas that differ with respect to the order and degree of nutrient limitations to crop production. 30 farmers' maize (Zea mays L.) fields (0.25-3.0 ha) were sampled in a 100 km2 area of peasant agriculture, approximately 40 km SE of Harare, Zimbabwe. Of these fields, eight were from an area of red clayey soils and 22 from an adjacent area of granitic sandy loams. Composite soil samples and whole maize plant samples were taken at the 8-12 leaf stage of maize growth. Earleaf samples were also taken from these same fields at maize tasseling to silking stages. Analyses of the N, P, K, Ca, Mg and Zn contents of the soil and plant samples dearly reflected the differences between the two contrasting soil areas, despite the considerable range of manuring and crop management practices used by the individual farmers. Fertility requirements were best indicated by the plant analyses, especially when used to calculate Diagnosis and Recommendation Integrated System (DRIS) indices, and least well by the soil test values. It was concluded that it might be feasible, in peasant agriculture, to conduct a soil and plant sampling survey to delineate geographic areas requiring different fertilizer treatments.
Keywords: DRIS; Spatial variability; Tissue analysis; Maize; Zimbabwe; Soil testing