SYSTEM OF RICE INTENSIFICATION: CLIMATE SMART RICE CULTIVATION SYSTEM FOR ADAPTATION AND MITIGATION OF CLIMATE CHANGE IMPACTS
How to increase food production using less water is one of the greatest challenges of the future. Crops and livestock use 70 percent of all water withdrawals and up to 95 percent in some developing countries. Paddy alone consumes about 60 percent of it. By 2025, 1.8 billion people are projected to be living in countries or regions with absolute water scarcity. To ensure food security for the growing population, expansion of rice-cropped area and continuous intensification of rice cultivation would likely increase greenhouse gas emission. Data on trade-offs between rice yield increase, water management and reduction in greenhouse gas emissions are urgently needed for innovation in cropping techniques. Modification of current cropping technique might be a way to reduce greenhouse gas emissions from rice soils. In this respect, System of Rice Intensification (SRI) has been introduced as an efficient, resource saving, and productive strategy to practice rice farming. Water management practices proposed for the SRI, cycles of repeated wetting and drying, were found to be beneficial to rice plant growth through increased nutrient availability leading ultimately to higher grain yields. In many countries, SRI have been producing average yields around 8 t/ha, twice of the present world average. With good use of these methods and with build-up of soil fertility, in microbiological as well as chemical and physical terms, yields can surpass 15 t/ha, pushing beyond what has been considered a yield ceiling for rice. SRI is reported to reduce greenhouse gases emissions up to 40%, water saving 25-65%, reduction in incidence of major rice pests and diseases, resistance to storm damage and drought, high economic return and shorter crop cycle. These make SRI technology relevant to the climate change adaptation and mitigation. The main concepts, ideas and principles of SRI SRI is an agro-ecological methodology for increasing the productivity of irrigated rice by changing the management of plants, soil, water and nutrients. The SRI practice consists of applied principles ranging from seed sorting, sowing, transplanting younger seedlings, weeding, and water management, all within the growing period of rice plants. i. Sorting out of the seeds Figure 1. Seed selection by egg and salt solution method ii. Raising seedlings in garden like nursery: This ensures a careful management of seedlings and easy uprooting as well as transplanting. Figure 2. Seedlings in nursery boxes/plots iii. Uprooting and transplanting time: The time between uprooting and transplanting should be between 15-30 minutes and the roots should be kept moist during this time. iv. Early transplanting of 8 to 15 days old seedlings, in addition to the provision of adequate buffer for the seedling from being damaged during transplanting, full tillering and optimal production occurs when the seedlings are transplanted before entering the fourth phyllochron of growth. Figure 3. A two-leaf seedling appropriate for transplanting v. Single, wide spaced transplanting Figure 4. Planting in square pattern with wide spacing vi. Early and regular weeding. This ensures that weeds do not compete with the rice plant. In addition, mechanical weeders aerate the soil. The roots need oxygen so as to be strong and healthy for optimal tillering and development of healthy rice grains. Figure 5. Use of mechanical weeders vii. Judicious water management: Alternate wetting and drying method rather than continuous flooding in the field.Wetting and drying the fields use less water and improve soil aeration and promote roots elongation that allow more tillering and rapid growth of paddy plants. Figure 6. Water management under alternate wetting and drying (AWD) viii. Use of fertilizers: Organic and/or inorganic fertilizers ix. No use of herbicides: The non-use of herbicides favours the sustainability of the ecosystem and the microorganisms whose activities are suitable for the growth of rice plants. Adoption World wide Assembled in Madagascar and promoted internationally since 2000. Validation of SRI benefits have been reported from more than 60 countries of Asia, Africa, and Latin America (SRI-Rice 2016a; FAO 2016; World Bank 2010).