Effect of Farmer Resource Endowment and Management Strategies on Spatial Variability of Soil Fertility in Contrasting Agro-ecological Zones in Zimbabwe

Abstract

Variability of soil fertility within and across farms poses a major challenge for increasing crop productivity in smallholder systems of sub-Saharan Africa (SSA). This study assessed the effect of farmers’ resource endowment and nutrient management strategies on variability in soil fertility and plant nutrient uptake between different fields in Gokwe South (average rainfall ~650 mm yr–1; 16.3 persons km–2) and Murewa (average rainfall ~850 mm yr–1; 44.1 persons km–2) districts, Zimbabwe. In Murewa, resource-endowed farmers applied manure (>3.5 t ha–1 yr–1) on fields closest to their homesteads (homefields) and none to fields further away (outfields). In Gokwe the manure was not targeted to any particular field, and farmers quickly abandoned outfields and opened up new fields further away from the homestead once fertility had declined, but homefields were continually cultivated. Soil-available phosphorus (P) was more concentrated in homefields (8–13 mg kg–1) of resource-endowed farmers than on outfields and all fields of poor resource farms (2–6 mg kg–1) in Murewa. Soil fertility decreased with increasing distance from the homestead in Murewa, while the reverse trend occurred in Gokwe South, indicating the impact of different soil fertility management strategies on spatial soil fertility gradients. In both districts, maize nutrient uptake showed deficiency in nitrogen (N) and P, implying that these were the most limiting nutrients. It was concluded that besides farmers’ access to resources, the direction of soil fertility gradients also depends on agro-ecological conditions, which influence resource management strategies.