Effective water management practices in irrigated rice to ensure food security and mitigate climate change in a tropical climate

Abstract

Rice is consumed by billions of people in the world and it is estimated that over 75 percent of the world’s rice is produced using continuous flooding water management practices. Studies indicate that continuous flooding has numerous disadvantages like low water use efficiencies and high emissions of methane. In order to ensure food security faced with the increasing competition for water and also to mitigate climate change, it is desirable to propose alternate water management practices to farmers. A study was carried out in Cameroon to compare the performance of local varieties of rice under different water management practices. The objectives were to: evaluate the effect of different water management practices on the growth and yield of three local rice varieties; and to determine the effect of various water management practices on the water use efficiency and water productivity of irrigated rice. Four water management regimes (continuous flooding maintained at a depth of 3 cm, intermittent flow at depths of, 3, 5 and 7 cm) and three local rice varieties were tested in a split-plot design with three replicates. The main plot factor was water management regime and the sub-plot factor, variety. The study indicates that the various water management practice do not significantly affect plant height (p>0.05). The varieties were significantly different in plant height (p<0.05). There was a significant (p<0.05) interaction between water management regime and variety on plant height. Between 39 and 47 % of the irrigation water used under continuous flooding as is practiced by most farmers in sub-Saharan Africa can be saved by the adoption of intermittent irrigation at 3-5 cm depth. The water use efficiency in intermittent irrigation with an application of 3 cm is about 100 % greater than that in continuous flooding irrigation with the same depth. For intermittent irrigation with a depth of 5 cm, the improvement is about 80 %. Intermittent irrigation produces yields which are not significantly different from continuous flooding irrigation but with a water use efficiency of up to 100 % higher. Intermittent water application with a depth of 3 cm had a water productivity of about 88 % higher than that obtained with continuous flooding irrigation. Intermittent irrigation with applied depths of 3-5 cm should therefore be promoted in sub-Saharan Africa to ensure food security while at the same time mitigating climate change through reduced production of methane.