Enhancing nitrogen use efficiency of rice

Background

Rice (Oryza sativa L.) is one of the most important staple food crops and plays a dominant role in the world food security. China is the largest rice producer in the world. Nitrogen (N) is a vital nutrient element for plant growth, development and reproduction, and can effectively increase crop yield. However, farmers tend to apply N fertilizers excessively to rice field in recent decades, leading to low nitrogen use efficiency (NUE) of rice production in China. Optimizing N management to improve NUE is a necessary measure to ensure high agricultural
productivity and economic efficiency, slow down the resource depletion, reduce
environmental risks, and achieve an intensification and sustainability of agricultural systems. Difficulties of rice N management in China lie in the smallholder farms, whereby different rice cultivars are grown in spatially heterogenous soil, and the soil fertility, phenological conditions and N input in various regions are all dramatically different, which makes it hard to design guidelines for the optimum N supply to the crop. To overcome these difficulties, a site-specific nutrient management method based on simple yield response and agronomic efficiency, the so-called Nutrient Expert (NE) system, was jointly developed by Chinese Academy of Agricultural Sciences, China (CAAS) and the International Plant Nutrition Institute (IPNI). However, the NE system has not evaluated formally from field experimentation. Also, to improve the NE, a better understanding of basic mechanisms on the N acquisition of rice is needed. To this end, we try to introduce a fully mechanistic crop growth model, GECROS, which captures the mechanisms of N uptake and other physiological processes, into the NE system for designing strategies to improve crop NUE.

Project Description

The objective of this research is to improve the NE so that it can used as a highly-efficient N fertilizer management system of rice production in China for minimizing nutrient losses from fields as well as for enhancing rice yield, profitability and agricultural and environmental sustainability. For that, a large-scale field experimentation was first implemented in China to first evaluate the existing NE system, in terms of rice growth, yield, NUE, economic benefits and system’s sustainability. Secondly, the data will also be used to assess the suitability of the GECROS model for main rice producing areas of China. Mechanisms for efficient N uptake and partitioning mechanisms of rice will be analyzed and quantified. Finally, the integrated GECROS-NE system will be designed and evaluated.