Soil fertility management effects on maize productivity and grain zinc content in smallholder farming systems of Zimbabwe

Abstract

Background and aims: Low soil zinc (Zn) threatens crop production and food nutrition in most cereal-based cropping systems in Africa. Agronomic management options that include farmers' locally available organic nutrient resources need to be evaluated in the context of Zn nutrition in staple cereals. A three-year study (2008-11) was conducted in two smallholder farming areas of eastern Zimbabwe to evaluate the influence of farmers' diverse soil fertility management practices on soil Zn status and effect on uptake patterns and nutritional value in maize (Zea mays L.). Methods: Participatory research approaches and formal surveys enabled identification of farmers' diverse soil fertility management practices, which were then classified into five main domains: manure or woodland litter + mineral fertilizer; sole mineral fertilizer; legume - maize rotation; and a non-fertilized control. Over 60 randomly selected farms in each study area were then surveyed for influence of identified practices on soil Zn status across the domains. Maize growth, yield and Zn uptake patterns were monitored on a sub-sample of 20 farms covering the five management domains in each study area. Results: Ethylenediaminetetraacetic acid (EDTA) extractable soil Zn ranged from 0. 50 to 2. 43 mg kg-1. Different farmer management practices significantly influenced Zn uptake (p < 0. 01). Combined use of organic and inorganic fertilizer yielded >2. 1 t ha-1 maize grain, against