Effect of Fallow on Pruning Biomass and Nutrient Accumulation in Alley Croppingon Alfisols of Tropical Africa

Abstract A study was conducted in long‐term alley cropping plots established in 1989 at International Institute of Tropical Agriculture (IITA), Ibadan, southwestern Nigeria to determine the seasonal and yearly dynamics of dry matter and nutrient concentrations of hedgerow pruning under continuous cropping and response to fallow of 1–3 years. At one year after Leucaena leucocephala transplanting, pruning was started at the 75 cm height. The pruning frequency increased from one to five times per year as trees grew. In continuous alley cropping without fertilizer application, pruning dry matter decreased gradually from a peak of 5 t ha−1 at 3 years after Leucaena transplanting to about 2.5 t ha−1 at 11 years after transplanting, while the ratio of dry season to wet season biomass increased. Within 5 years after establishment, nitrogen (N) and phosphorus (P) concentrations in pruning decreased and Mg increased with the continuous cropping. Fallow clearly increased pruning biomass and nutrient concentrations. ...