Better nutrient management strategy for rice-wheat, rice-rapeseed and rice-rice cropping systems

The agricultural regions of China under rice-upland crop rotations are important for grain crop production, commercial fertilizer use, and ecological sustainability. Therefore, research on the technology and strategies of better crop fertilization in this region are important to help achieve the goal of optimizing fertilizer use to increase fertilizer use efficiency in the country. Under the support from IPNI China program and the Special Fund for Agro-scientific Research in the Public Interest of the MOA China, the project cooperators from Wuhan Botanical Garden of CAS carried out a series of field experiments with rice-wheat, rice-rapeseed, and early rice-late rice rotations for key technologies and strategies of efficient fertilization in Jinmen County of Hubei Province, and Changsha County of Hunan Province.

The results from 2017 showed that compared to urea, the application of controlled-release urea significantly increased nitrogen (N) fertilizer use efficiency by 36 to 93%, and slightly increased rice yield. Rice straw-return treatments showed some negative effect on late rice yield and N use efficiency, but the effect was not significant. The fertilizer recommendations from the Nutrient Expert® fertilizer decision support tool (NE) significantly increased the economic efficiency of fertilization, increased the fertilization output/input ratio from 9.8 to 11.5 kg/kg, and increased N use efficiency from 36 to 55% for rice, wheat, and rapeseed.

A large amount of commercial fertilizer is used for rice cultivation in China, however, the use efficiency is rather low. Researchers from the IPNI southeast China Program collected data from the rice fertilization field experiments from 2001 to 2012. Using the data, the researchers established a novel approach for rice fertilizer recommendation based on the fertilization for Agronomic Efficiency (AE) and Sustainable Yield Index (SYI). This approach was able to better estimate fertilizer rates, thereby significantly increasing rice yield, economic benefit, and agronomic efficiency of fertilizer use. It is an effective approach for improving fertilizer recommendations in rice, and potentially to other crops. The experimental results have been published in Chinese and English scientific journals during 2015 to 2017.