Optimizing Nitrogen Application for Chinese Ratoon Rice Based on Yield and Reactive Nitrogen Loss

Ratoon rice (RR) has been regarded as a labor-saving and beneficial production system. Nitrogen (N) surplus reactive N losses (Nr losses) are effective environmental indicators used to evaluate the performance of management. Few studies have assessed Nr for Chinese RR. In this study, RR planting areas were divided into South China (SC), southern part East (SEC), Central (CC), northern (NEC), Southwest (SW). also calculated based on 782 using quadratic model under optimized management highest yield (OPT-yield), N-use efficiency (NUE) (OPT-NUE), grain uptake (OPT-N uptake). The yields in five regions ranged from 9.98 13.59 t ha−1. high-yield record was observed SEC, while low-yield NEC. lowest found NEC SC, respectively. reduced, maintained CC, NEC, SW OPT-yield OPT-N uptake, reduced when targeting NUE. Farmers should be encouraged plant SEC CC. good choice measures conducted three other regions. To achieve win–win situation both environment, could serve improve current conventional practices.