EFFECTS OF IRRIGATION WATER REGIMES, SOIL TYPES AND THEIR INTERACTION ON WATER USE AND WATER PRODUCTIVITY FROM RICE (ORYZA SATIVA L) CULTIVATION IN MWEA, CENTRAL KENYA
Kenyan rice production is an important component for national food security. However, most rice producers in Kenya still use the conventional continuous flooding method that requires a lot of water and produces high amounts of methane (CH4), a potent greenhouse gas (GHG). The changing weather patterns due to climate change and deforestation has the potential to reduce the water availability for rice production globally. It is therefore necessary to assess locally feasible watersaving irrigation technologies in rice production that can be adapted to not only reduce water use but increase or maintain yield. One such water-saving technology is the alternate wetting and drying (AWD). This study was therefore conducted to assess the water saving and productivity in rice irrigation in Mwea Irrigation Scheme, Kenya during August – December 2017 rice growing season under AWD water application method in comparison to the conventional continuous flooding (CF) for two soil types (Vertisols [VS] and Nitisols [NS]) commonly found in the scheme. Compared with the CF, water saving in the VS and NS soils under AWD was 26 % and 45 % respectively. There were no significant difference (P < 0.05) in yield with the introduction of AWD in both soil types and consequently productivity was 28% and 78% higher in the VS and NS respectively under AWD compared to the CF. Rice grain yield is extremely sensitivity water stress and it is therefore important to fine tune the draining and re-flooding cycle of the rice fields under AWD to site specific conditions i.e., soil type and weather conditions.