Predicting the Nitrogen Quota Application Rate in a Double Rice Cropping System Based on Rice–Soil Nitrogen Balance and 15N Labelling Analysis

Excessive nitrogen (N) fertilization, low use efficiency, and heavy pollution are the dominant issues that exist in intensively cultivated double rice cropping systems China. Two-year field 15N microregion experiments were conducted to evaluate N fate a soil-rice system under series of different rate treatments from 2020 2021. The economic application simultaneously improved yield efficiency rotation was also investigated. Results demonstrated soil residues mineralized accounted for more than 58.0% 53.2% total input early late seasons, respectively. Similarly, most absorbed by rice, ranging 43.7% 55.6% 36.8% 54.7% rice. Rice significantly decreased with increasing application, while grain its uptake increased when below 150 kg ha−1 200 Exceeding this point limited formation. apparent recovery rate, residual loss 23.5–34.4%, 17.0–47.1%, 26.0–47.8% 32.8–37.3%, 74.2–87.0%, 71.5–92.1% linear plateau analysis further indicated recommended (118.5–152.8 169.9–186.2 rice) can not only maintain relatively higher utilization but reduce residue. Our results provide theoretical guidance improving management double-cropping fields southern