Influence of nutrient management strategies on variability of soil fertility, crop yields and nutrient balances on smallholder farms in Zimbabwe

An improved understanding of soil fertility variability and farmers' resource use strategies is required for targeting soil fertility improving technologies to different niches within farms. We measured the variability of soil fertility with distance from homesteads on smallholder farms of different socio-economic groups on two soil types, a granite sand and a red clay, in Murewa, northeast Zimbabwe. Soil organic matter, available P and CEC decreased with distance from homestead on most farms. Soil available P was particularly responsive to management, irrespective of soil type, as it was more concentrated on the plots closest to homesteads on wealthy farms (813 mg kg(-1)), compared with plots further from homesteads and all plots on poor farms (2-6 mg kg(-1)). There was a large gap in amounts of mineral fertilizers used by the wealthiest farmers (> 100 kg N and > 15 kg P per farm; 39 kg N ha(-1) and 7 kg P ha(-1)) and the poorest farmers ( 26 kg N ha(-1) and > 13 kg P ha(-1)),but decreased to 10-20 N and 6-9 kg P per plot (<20 kg N ha(-1) and 13 kg P ha(-1)) in mid-fields and -7 to +10 kg N and -1 to +1 kg P per plot (<10 kg N ha(-1) and