Aerobic rice for water-saving agriculture. A review

The increasing shortage of water resources has led to the development and adoption of aerobic rice system, which saves water input and increases water productivity by reducing water use during land preparation and limiting seepage, percolation, and evaporation. Aerobic rice also reduces labor requirement and greenhouse gaseous emission from rice field. In an aerobic rice system, the crop can be dry direct-seeded or transplanted and soils are kept aerobic throughout the growing season. Supplemental irrigation is applied as necessary. Aerobic rice cultivars are adapted to aerobic soils and have higher yield potential than traditional upland cultivars. Grain yields of 5-6 tha(-1) can be reached in aerobic rice system. However, yield decline or even complete failure of aerobic rice under continuous monocropping threatens the widespread adoption of aerobic rice technology. Here, we review research findings on possible causes responsible for yield decline of continuous aerobic rice. Our main findings are: (1) both biotic and abiotic factors are involved in the continuous cropping obstacle of aerobic rice; (2) recent research focused on abiotic factors related to the continuous cropping obstacle, such as soil pH increase, ammonia toxicity, and nutrient deficiencies; and (3) strategies which will help in mitigating the continuous cropping obstacle of aerobic rice include selection of new aerobic rice cultivars, nutrient management practice, crop rotation, and soil acidification. Identifying the causes responsible for continuous cropping obstacle of aerobic rice and adopting effective strategies are crucial to achieve sustainability of aerobic rice.