Lower soil nitrogen-oxide emissions associated with enhanced denitrification under replacing mineral fertilizer with manure in orchard soils

Pinshang Xu; Zhutao Li; Shumin Guo; Davey L Jones; Jinyang Wang; Zhaoqiang Han; Jianwen Zou

doi:10.1016/j.scitotenv.2024.171192

Lower soil nitrogen-oxide emissions associated with enhanced denitrification under replacing mineral fertilizer with manure in orchard soils

Sci Total Environ. 2024 Apr 15:921:171192. doi: 10.1016/j.scitotenv.2024.171192. Epub 2024 Feb 23.

Authors

Pinshang Xu¹, Zhutao Li¹, Shumin Guo¹, Davey L Jones², Jinyang Wang¹, Zhaoqiang Han³, Jianwen Zou¹

Affiliations

¹ Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing 210095, China.
² School of Environmental and Natural Sciences, Bangor University, Bangor, Gwynedd, LL57192UW, UK; SoilsWest, Centre for Sustainable Farming Systems, Food Futures Institute, Murdoch University, Murdoch, WA, 6150, Australia.
³ Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: zqhan@njau.edu.cn.

PMID: 38401727
DOI: 10.1016/j.scitotenv.2024.171192

Abstract

Emerging evidence suggests that replacing mineral fertilizers with organic livestock manure can effectively suppress reactive gaseous nitrogen (N) emissions from soils. However, the extent of this mitigation potential and the underlying microbial mechanisms in orchards remain unclear. To address this knowledge gap, we measured nitrous and nitric oxide (N₂O and NO) emissions, microbial N cycling gene abundance, and N₂O isotopomer ratios in pear and citrus orchards under three different fertilization regimes: no fertilization, mineral fertilizer, and manure plus mineral fertilizer. The results showed that although manure application caused large transient peaks of N₂O, it reduced cumulative emissions of N₂O and NO by an average of 20 % and 17 %, respectively, compared to the mineral fertilizer treatment. Partial replacement of mineral fertilizers with manure enhanced the contribution of AOA to nitrification and reduced the contribution of AOB, thus reducing N₂O emissions from nitrification. Isotope analysis suggested that the pathway for N₂O production in the soils of both orchards was dominated by bacterial denitrification and nitrifier denitrification. The manure treatment reduced the ratio of denitrification products. Additionally, the dual isotope mixing model results indicated that partially replacing mineral fertilizers with manure could promote soil denitrification, resulting in more N₂O being reduced. N-oxide emissions were on average 67 % higher in the pear orchard than in the citrus orchard, probably due to the differences in soil physicochemical properties and growth habits between the two orchards. These findings underscore the potential of partially replacing mineral fertilizers with organic manure in orchards to reduce gaseous N emissions, contributing to the transition towards environmentally sustainable and climate-smart agricultural practices.

Keywords: Climate change; Climate-smart agriculture; Greenhouse gas; Mitigation option; Soil nitrogen cycle.