Rice System

Traditional methods of growing rice involve the continuous flooding of rice fields and only draining at the time of harvest . Continuous flooding wastes lots of water and leaches soluble nutrients . More than 60 of applied N is lost during via NH3 volatilization from the floodwater . Microbial activity is also reduced which reduces the decomposition of soil organic matter by 50

Nitrogen (N ) is the most important nutrient in the production of rice Nitrogen is usually found as ammonia in anaerobic soils and in Nitrate (NO3 ) in aerobic soils . The mineralization of organic nitrogen

compounds provides the main supply of natural N supply for plants and microorganisms

System of Rice Intensification (SRI ) utilizes aerobic watering management methods which involves repeated wetting and drying of the rice field . This watering strategy was proven to provide N in both of its forms ammonia and nitrate . It also increased availability of nutrients leading to higher grain growth and better yields

The rewetting of dry soil produces a large flush of N mineralization and availability . This is because a significant portion of the soil microorganisms die during the drying and rewetting of the field . The youthful state of the microbial population that develops after rewetting causes enhanced N mineralization . Another reason would be the mineralization of dead microbial cells by the remaining microflora

References

Ceesay , M Uphoff , N (2002 . The Effects of Repeated Soil Wetting and Drying on Lowland Rice Yield with System of Rice Intensification (SRI Methods . Cornell University

Maire , N , J . M . Besson , H . Sutter , G . Hasinger , and A . Palasthy (1990 . Influence of cultural practices on the equilibrium of physico-chemistry and biology of agricultural soils . Swiss Agricultural Research (Schweizerische Landwirtschaftliche Forschung ) 29 , 61-74...