Global reactive nitrogen loss in orchard systems: A review

• Published in: The Science of the total environment 2022-05, Vol.821, p.153462-153462, Article 153462
• Main Authors: Zhao, Huanyu, Lakshmanan, Prakash, Wang, Xiaozhong, Xiong, Huaye, Yang, Linsheng, Liu, Bin, Shi, Xiaojun, Chen, Xinping, Wang, Jie, Zhang, Yueqiang, Zhang, Fusuo
• Format: Article
• Language: English
• Subjects: Agriculture - methods; Fertilizers - analysis; N application; N balance; N loss factors; Nitrogen - analysis; Nitrous Oxide - analysis; Orchard types; Orchards; Regions; Soil
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.153462

Orchards account for about 5% of the agricultural land in the world, however the amount of nitrogen (N) fertilizer input in orchards is relatively large. Little is known about N input and its impact in orchards at the global scale. Therefore, in this study we systematically evaluated reactive nitrogen (Nr) loss in global orchards. A meta-analysis of 97 studies reported from 2000 to 2021 from different countries showed that the mean global N fertilizer input in orchards was 303 kg N ha−1 yr−1, and the estimated emission factor (EF) of nitrous oxide (N2O) and ammonia (NH3) were 1.39% and 3.64%, respectively. Also, during the same period, orchard nitrate leaching factor (LF) reached 18.5%, and the runoff N loss factor (RF) and net fruit N removal factor (NRF) were estimated to be 2.75% and 5.31%, respectively. The apparent N balance of the global orchard system reached 68.4% of N input. N application increased the Nr loss in various pathways in the orchard. The N2O and NH3 emission and nitrate leaching were linearly correlated with N fertilizer application, and overuse of N resulted in substantial Nr loss. Regionally, the total Nr loss in developing countries was higher than developed countries. Average N input (405 kg N ha−1 yr−1) and Nr loss (102 kg N ha−1 yr−1) of orchards in Asia were the highest. The NH3 volatilization and runoff N loss of deciduous orchards were significantly higher than that of evergreen orchards. N application increased fruit yield, but excessive N input reduced the net fruit N removal (FNR). The results reported here fill an important knowledge gap of N balance analysis of orchards at a global scale and provided a framework for optimizing N management to achieve sustainable fruit production. [Display omitted] •The estimated global orchard reactive nitrogen (Nr) loss factor is 26.3% of N input.•Nitrate leaching (18.5% of N input), the major Nr loss pathway in orchards globally.•Large differences in Nr loss among different regions and orchard types.•The apparent N balance of the global orchard system reached 68.4%.