Nitrogen Uptake and Use Efficiency in Rice

Abstract

Rice is a stable food for a large proportion of the world’s population. Most of the rice is produced and consumed in Asia. Rice is produced under both upland and lowland rice systems, with about 76% of the global rice produced from irrigated-lowland rice systems. Nitrogen (N) is one of the most important inputs in the production of rice. Recovery efficiency of N is less than 50% in both upland and lowland systems. Most of the applied N is lost due to volatilization, leaching, denitrification, and soil erosion. In addition, fertilizers account for almost half of energy used in world agriculture, and the manufacture of N fertilizer is about 10 times more energy intensive than that of P and K fertilizers. Therefore, improving N use efficiency is important not only to improve yield and reduce cost of production but to avoid environmental pollution and to maintain sustainability of the cropping system. Production practices which can improve N use efficiency are liming acid soils, supplying N in adequate rates, use of proper sources, use of suitable methods and time of application, use of crop rotation, use of cover crops, adopting conservation tillage system, planting N efficient genotypes, and control of diseases, insects, and weeds.