Potential Role of Biochar in Water Management in Rainfed Agriculture
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Abstract The economies of the three East African region (Uganda, Kenya and Tanzania), which is the region of interest in this study still rely largely on rainfed agriculture accounting to approximately 80% of the total agricultural production. With the increasing threats from climate variability, the region is prone to extreme conditions of drought and floods. Inadequate soil moisture and low soil fertility have been the challenges facing rainfed agriculture in the region and several approaches have been employed to help manage agricultural water sustainably. Previous studies indicate that incorporation of biochar into sandy soil improves its water retention capacity. This study demonstrates how addition of biochar produced from different feedstock biomass of sugarcane (Saccharum officinarum Linn) trash and bamboo (Arundinaria alpina) leaves and branches, all obtained from the region using both the laboratory controlled equipment at 350 oC, 450 oC and 550 oC and a traditional stove, to sandy soil has the potential improve the soil’s water holding capacity. This way, biochar can thus play a significant role in water management in agriculture in the East African region with the aim of reducing agricultural input and maximizing crop yields. For the traditional stove, it was difficult to control the temperature while producing the biochar but the highest steady temperature reached during production was recorded. The hydrologic properties including water holding capacity and hydrophobicity of sandy soil, biochars and soil-biochar mixtures were measured using the gravimetric method and the molarity of ethanol drop test respectively. Additionally, porosity was determined using the mercury porosimetry method in order to compare the pore size distribution of the biochars with their hydrologic properties. Biochars produced from different feedstock biomass under different production conditions varied in their hydrologic behavior and influenced soil’s hydrologic properties differently when added to it. The study demonstrates water retention increases in a sandy soil after addition of 2, 5 and 7 weight % biochar (20, 50, and 70 t ha-1 respectively).