Water Management in Rice

Rice is the staple food for billions of people in the world. This crop has important cultural, economic, and social impacts on the lives of people. One of the major challenges for food security in the world is ever increasing population growth requiring a significant increase in food supply. This is further threatened by water scarcity. Water shortage is a major threat for sustainable rice production worldwide. It is of utmost importance to explore alternate ways of rice production by using less water for food security. Therefore, the focus is mostly concentrated on water-saving rice production systems in modern agricultural research. Such methods may include reduction of unproductive water outflow, alternate wetting and drying, the system of rice intensification, direct seeding, aerobic rice system, scheduling of irrigation technique using tensiometer, and ground cover rice production system. All these technologies can significantly reduce water demand for rice production and can improve water use efficiency (WUE). These technologies, however, can reduce yield under certain conditions, especially when the existing lowland varieties are used. Efforts are being made to minimize yield losses and improve water economy. For this purpose, new approaches are being explored. Molecular biotechnology is being utilized to develop superior rice varieties with improved drought tolerance, WUE, and transpiration efficiency. These approaches have the potential to provide high and sustainable rice yield in non-flooded conditions. Adoption of these technologies will cause a shift of rice cultivation systems from continuously anaerobic (flooded) to partly or completely aerobic (non-flooded) systems. This change will be associated with some benefits such as conservation of water and a decrease in methane emission. Some potential negative impacts of this shift might be evident in the form of decline in soil organic matter (excluding rice and wheat production systems) and release of nitrous oxide from the soil. An effective integrated natural resource management system needs to be developed to address these issues and to make rice cultivation profitable with increased soil aeration and to maintain the productivity, environmental safety, and sustainable ecosystem. In this chapter, efforts have been made to discuss various approaches for water management in rice production system to increase yield with reduced water demand.