Enhancing Water Use Efficiency Using Crop Growth Simulation Models for Developing Adaptation Strategies Under Current and Future Scenarios.

A combination of crop growth simulation models and GCM outputs can be used effectively for not only generating future scenarios but also in identifying researchable issues and management options that will enable development of adaptation and mitigation strategies. It has been estimated that in the next two decades the share of water to agriculture in India is likely to reduce by 10 to 15 per cent but 25 to 30 per cent more water would be needed to achieve the production targets for ensuring food security. Models like PRECIS, CROPWAT, DSSAT, RZWQMZ and HadCM3 have been used for estimating the change in crop water requirements in 2020s, 2050s and 2080s scenarios and identifying tools and management options that will help in combating the adverse impact of climate change and global warming. Most of the GCMs predict that in the Indian Subcontinent the increase in temperature would be more in winter season (rabi) as compared to monsoon (kharif) season and a relatively greater increase in the minimum temperature. Simulation studies were carried for several important crops viz. wheat, maize, rice, sorghum, groundnut, etc. The results indicate that there would be increase in crop water requirement varying anywhere from 1% to 20% depending upon the crop and the location in the 2020 and 2050 scenarios. Late sown and very late sown wheat would not only increase crop water requirement by 3 to 5 per cent in the 2020 scenario but also reduce yield by up to 6%. However, a combination of an improved variety along with better management can increase the yield up to 10% in the 2020 scenario in addition to savings in water. In case of rice, simulation studies have shown that irrigation, land management, soil moisture and proper fertilization strategy could result in reduction of Global Warming Potential (GWP) and water requirement without any sacrifice in yields.