Combining manure with mineral N fertilizer maintains maize yields: Evidence from four long-term experiments in Kenya

Crop productivity in sub-Saharan Africa cannot be substantially improved without simultaneously addressing short-term crop nutrient demand and long-term soil fertility. Integrated fertility management tackles both by the combined application of mineral fertilizers organic resource inputs but few studies examined its‘ effectiveness. To address this knowledge gap, study analysed maize yield trends four (31–37 cropping seasons) field experiments Kenya with contrasting textures under different climates. All sites had two seasons per year, received a base P K fertilization tested combinations addition (1.2 4 t C ha-1 yr-1 ranging from farmyard manure, to high-quality Tithonia diversifolia Calliandra calothyrsus material low-quality saw dust), (+N) (-N) N fertilizer (120 kg season-1). General across site specific were analyzed. Across sites, no-input control experienced significant average reductions 50 over period. In contrast, treatment manure +N maintained yields at 1.2 yr-1. High initial following additions Calliandra, reduced time. Assessment showed specificity trends. For example, climatically favorable western gains high quality resources yr-1, leading up 8 season, while central losses, 3.5 season. Yield for ± treatments was stonger than treatments, e.g. clayey end no differences between N, except treatment. Yet, plus consistently achieved highest all (about 5 dry matter) most N-efficient At realistic rates, integrated is best sustained N. Mixed crop-livestock systems are key ingredients smallholder Africa.