Integrating rainwater harvesting and organic soil amendment to enhance crop yield and soil nutrients in agroforestry

Abstract More than 90% of rainfed croplands in Sub-Saharan Africa (SSA) are severely affected by highly intermittent rainfall and frequent drought limiting crop productivity in the region. Besides, 27.1% of the population in SSA are currently food insecure and this is likely to increase with the current rapid population growth in the region. Soil erosion and water scarcity remain to be the core problem affecting agricultural productivity of smallholder farming. In the current study, we analysed rainwater harvesting assisted small-scale agroforestry system in order to mitigate both soil erosion and water scarcity issues simultaneously. The system included in-situ rainwater harvesting, soil organic amendment (raw poultry litter, poultry litter biochar, wood ash) and an agroforestry system (AFS) containing maize, barley- Eucalyptus globulu s all intercropped in a holistic approach. The effect was evaluated on selected soil parameters and crop yield in a field experiment on a completely randomized design. The treatments were poultry litter (PWAFS), poultry litter biochar (BWAFS) wood ash (AWAFS) with supplementary irrigation (WAFS) and agroforestry system AFS (control). The first three treatments contained poultry litter, poultry litter biochar and wood ash along with rainwater harvesting respectively while the fourth treatment contained only rainwater harvesting. Besides, a control plot-AFS was assigned with neither rainwater harvesting nor soil organic resources. The result indicated that BWAFS increased the pH by 19.4% followed by AWAFS and PWAFS (9%). Maximum and minimum SOM (2.26%, 1.21%) were observed under BWAFS and the control (AFS) respectively. BWAFS significantly increased Av.P by 78.1% while WAFS increased by 40% compared to the control. Similarly, BWAFS and PWAFS had significant effect on maize yield with increase by 74% and 36% respectively. The study concluded that integrating rainwater harvesting and soil amendment with agroforestry systems can enhance crop yield and soil nutrient levels. Therefore, such agricultural practices should be adopted by smallholder farmers in areas with limited water and nutrients levels.