Enhancing water use efficiency of cassava and sorghum based cropping systems in drylands

Soil moisture flow characteristics, infiltration and storage in the root zone determine the overall availability and use efficiency of water in crop production. This study is evaluating the effects of cropping systems and tillage management strategies on soil water flows in cassava and sorghum cropping systems in the drylands of eastern Uganda. The study site is in Uganda’s Teso farming system on Petroferric haplustox soils. The experiment is set in a randomised complete block design laid out as split plot with treatments (sole cassava; sole sorghum; sole cowpea; cassava + sorghum; cassava + cowpea; sorghum + cowpea) replicated three times. Two tillage management practices (mouldboard; ripper ploughing) constitute the blocks. Main parameters measured are; leaf area index, precipitation, infiltration, soil moisture storage, evaporation and transpiration. The water balance equation, calculated from precipitation, changes in soil water storage within the profile, and the vertical water flux below the root zone, is used to estimate actual evapotranspiration (ETa). Water use efficiency (WUE) determined as a ratio of yield (Y) to actual evapotranspiration (ETa). The study is in the initial stages of data collection however, surface runoff is negligible in both mouldboard and ripper ploughing. This is augmented by the low slope gradient (0 - 3%) and the soil surface roughness observed. The trend in soil moisture storage is almost similar in the first 4 weeks after planting in all cropping treatments. Expected outputs of the research are: water distribution (flow and storage) in the different cropping systems and tillage management, water used in the different cropping systems quantified, cropping pattern with the best water use efficiency identified, and tillage management practices that reduce surface flow and increase green water flow in cassava and sorghum crops identified.