Enhancing maize (Zea mays L.) yields in limited fertilizer farming systems through soil nutrient recycling in Sub-Saharan Africa

摘要

Sub-Saharan Africa (SSA) is dominated by small holder-farmers who have limited access to chemical fertilizers. This study was conducted in Eastern Uganda with a primary objective to investigate the intricate relationship between crop residue quality, soil carbon and nitrogen mineralization, and their collective impact on maize yields and residue quality. Employing a randomized completely block design (RCBD) over a two-year period (2013 - 2014), the study involved cattle manure, Tithonia compost each applied at 2t/ha, and maize residues which was applied at 4t/ha. Maize grain yield, maize stover and soil properties were measured at the harvesting period. Particularly, soil from each treatment plots and control was collected for laboratory chemical analysis to determine the Nitrogen(N), Phosphorus (P), potassium (K) content. At the end of each growing period, maize residues were also collected and analysed for the N, P, K content. Carbon (C) and N mineralization experiments were conducted in the laboratory that tested the potential of these organic amendments for soil nutrient release. In 2013 maize grain yield increased by 87, 27 and 13 following the application of cattle manure, Tithonia compost and maize residues compared to control plots, respectively. In 2014 maize grain yields improved significantly from 59 to 106 in plots with organic amendments. Over the two years, maize stover yield increased by 25 in the first year and a 56 in the second year compared to control plots. The impact of these organic materials also resulted in the doubling of N, P and K content in maize residues, particularly when cattle manure and Tithonia compost were applied. This, in turn, resulted in improved carbon mineralization and enhanced net nitrogen mineralization. This study demonstrated that application of organic soil amendments improves both maize yields and the quantity and quality of subsequent maize residues. For better results long-term application of these organic amendments and maize residues have the potential to reduce the need for additional inputs and could support a more sustainable and economically viable approach to maize production.