College of Horticulture, Jinling Institute of Technology, Nanjing, 210038, PR China; Scientific Observation and Experimental Station of Arable Land Conservation of Jiangsu Province, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China.
Powerchina Zhongnan Engineering Corporation Limited, Changsha, 410014, China.
J Environ Manage. 2022 Dec 15;324:116335. doi: 10.1016/j.jenvman.2022.116335. Epub 2022 Sep 28.
Unreasonable water (W) and inorganic nitrogen (N) fertilization cause an intensification of soil greenhouse gas (GHGs) emissions. W-N interactions (W × N) patterns can maximise the regulation of soil GHGs efflux through the rational matching of W and N fertilization factors. However, the effects of W × N patterns on soil GHGs efflux and the underlying mechanism remain unclear. In this study, urea fertilizers were applied to paddy soils in a gradient of 100 (N100), 80 (N80), and 60 mg kg (N60) concentrations. Flooding (W1) and 60% field holding capacity (W2) was set for each N fertilizer application to observe the effects of W × N patterns on soil properties and GHGs efflux through incubation experiments. The results showed that W significantly affected soil electrical conductivity and different N forms (i.e., alkali hydrolyzed N, ammonium N, nitrate N and microbial biomass N) contents. Soil organic carbon (C) content was reduced by 14.40% in W1N60 relative to W1N100, whereas microbial biomass C content was increased by 26.87%. Moreover, soil methane (CH) fluxes were low in all treatments, with a range of 1.60-1.65 μg CH kg. Soil nitrous oxide (NO) and carbon dioxide (CO) fluxes were significantly influenced by W, N and W × N. Global warming potential was maintained at the lowest level in W1N60 treatment at 0.67 g CO-eq kg, suggesting W1N60 as the preferred W × N pattern with high environmental impact. Our findings demonstrate that reduced N fertilization contributes to the effective mitigation of soil NO and CO efflux by lowering the soil total N and organic C contents and regulating soil microbial biomass C and N.
不合理的水分（W）和无机氮（N）施肥会加剧土壤温室气体（GHGs）排放。W-N 相互作用（W×N）模式可以通过合理匹配 W 和 N 施肥因子来最大限度地调节土壤 GHGs 通量。然而，W×N 模式对土壤 GHGs 通量的影响及其潜在机制仍不清楚。本研究采用梯度浓度的 100（N100）、80（N80）和 60 mg kg（N60）尿素施肥处理稻田土壤，分别设定淹水（W1）和田间持水量的 60%（W2）进行 N 肥施用，通过培养实验观察 W×N 模式对土壤性质和 GHGs 通量的影响。结果表明，W 显著影响土壤电导率和不同 N 形态（即碱解 N、铵态 N、硝态 N 和微生物生物量 N）含量。与 W1N100 相比，W1N60 处理下土壤有机碳（C）含量降低了 14.40%，而微生物生物量 C 含量增加了 26.87%。此外，所有处理下土壤甲烷（CH）通量均较低，范围为 1.60-1.65 μg CH kg。土壤氧化亚氮（NO）和二氧化碳（CO）通量均受 W、N 和 W×N 的显著影响。在 W1N60 处理下，全球增温潜势（GWP）最低，为 0.67 g CO-eq kg，表明 W1N60 是 W×N 模式的首选，具有较高的环境影响。本研究结果表明，通过降低土壤全氮和有机碳含量以及调节土壤微生物生物量 C 和 N，减少 N 施肥有助于有效减少土壤 NO 和 CO 通量。
