Leaching is the main pathway of nitrogen loss from a citrus orchard in Central China

• Published in: Agriculture, ecosystems & environment Vol. 356; p. 108559
• Main Authors: Luo, Yue, Wu, Xian, Xiao, Hengbin, Toan, Nguyen-Sy, Liao, Bin, Wu, Xiao, Hu, Ronggui
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2023
• Subjects: Ammonia volatilization; Citrus orchards; Leaching; Nitrogen mass balance; Nitrous oxide emission; Runoff; Ammonia volatilization; Runoff; Leaching; Citrus orchards; Nitrous oxide emission; Nitrogen mass balance
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2023.108559

Due to the high application rates and low utilization efficiency of inorganic nitrogen (N) fertilizer, conventional citrus orchards tend to cause N losses and extensive pollution. In order to address these issues, it is essential to identify the leading cause of N loss by citrus orchard N mass balance. In the present study, a two-year field experiment was performed on 4 different treatments (CK: no N fertilizer; CF: conventional N fertilizer; NR: 70% of conventional N fertilizer; OM: NR with organic manure) to quantify the pathways of N loss in citrus orchards in Hubei Province, China. Our findings revealed that leaching (17.0%) was the dominant N loss pathway in the conventional citrus orchard of central China, followed by runoff (2.9%), NH3 volatilization (2.3%), and N2O emission (0.5%). Reduced N fertilizer rates (−30.0%) led to a significant reduction in gaseous N loss (−34.9%), runoff N loss (−20.3%), and N leaching (−13.0%) via the reduced content of soil NH4+ and soil NO3-. Interestingly, the presence of organic manure reduced 15.2% of runoff N loss, 3.8% of N leaching and 6.9% of total N loss via reduced soil NO3-, but increased 39.6% of gaseous N loss via increased soil DOC. On the other hand, the low N fertilizer rates suppressed N uptake of citrus by reducing the content of soil NO3-, while organic manure promoted N uptake of citrus via the increased content of soil DOC. Overall, using organic manure as a substitute provides a better solution to fertilization for the citrus orchards in central China compared to reducing N fertilizer rates. •The total N loss accounts for 24–35% of total N input for the citrus orchards.•Leaching is the principal pathway of N loss, contributing 57–61% to total N loss.•Low N fertilizer rates mitigate N loss in all N loss pathways and N uptake in citrus.•Organic manure reduces total N loss via the reduced content of soil NO3-.•Organic manure improves citrus N uptake via the increased content of soil DOC.