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; Beijing Key Laboratory of Biodiversity and Organic Farming, Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China.
Sci Total Environ. 2021 Apr 10;764:142884. doi: 10.1016/j.scitotenv.2020.142884. Epub 2020 Oct 14.
A thorough elucidation of the coupled effects of N fertilization and straw incorporation on NO emissions and N losses is crucial for alleviating negative environmental impacts in intensively farmed regions. Here, we conducted an in situ N tracing experiment to assess the source of NO emissions and fate of fertilizer-N in soil intensively farmed with summer maize (Zea mays L.). Four treatments, i.e., no N fertilization and no straw incorporation (N0S0), straw incorporation only (N0S1), N fertilization only (N1S0), and N fertilization plus straw incorporation (N1S1), were established in the study. Compared with straw removal, straw incorporation increased the seasonal NO emissions by 22.3% but reduced the NO emissions per unit of applied N by 6.22% (P > 0.05). The emission of fertilizer-derived NO occurred mainly in the 13-17 days after fertilization; thereafter, the ratio of fertilizer-derived NO fluxes would be less than 5%. N fertilization significantly stimulated non-fertilizer-derived NO emissions and soil CO fluxes, especially when straw was incorporated (P < 0.05), indicating that N fertilization might have triggered the mineralization of straw-N and/or native soil organic N. The soil NO-N concentration in straw-incorporated plots tended to be lower than that in straw-removed plots, especially after N fertilization events. Straw incorporation sequestered 52.5% (27.4 kg N ha) more fertilizer-N in 1 m of soil than straw removal (P < 0.05) while significantly increasing the fertilizer-N harvest index and maintaining grain yield. Overall, compared with straw removal, straw incorporation significantly reduced total fertilizer-N losses (by 12.8%, i.e., 14.58 kg N ha; P < 0.05). Our study highlights the benefits of straw incorporation for increasing in-season and multiseason fertilizer-N use efficiencies and alleviating fertilizer-N-induced environmental costs in intensively farmed regions.
深入阐明氮肥施用和秸秆还田对 NO 排放和氮素损失的耦合效应，对于缓解集约化种植区的负面环境影响至关重要。在这里，我们进行了一项原位氮示踪实验，以评估集约化种植夏玉米（Zea mays L.）土壤中 NO 排放的来源和肥料氮的归宿。本研究设置了 4 种处理，即不施氮肥和不还秸秆（N0S0）、只还秸秆（N0S1）、只施氮肥（N1S0）和施氮肥加还秸秆（N1S1）。与秸秆移除相比，秸秆还田增加了 22.3%的季节性 NO 排放，但降低了单位施氮量的 NO 排放（P＞0.05）。肥料衍生的 NO 排放主要发生在施肥后 13-17 天；此后，肥料衍生的 NO 通量比将小于 5%。氮肥显著刺激了非肥料衍生的 NO 排放和土壤 CO 通量，尤其是当秸秆还田时（P＜0.05），表明氮肥可能引发了秸秆-N 和/或土壤有机 N 的矿化。秸秆还田处理的土壤 NO-N 浓度往往低于秸秆移除处理，尤其是在施氮事件之后。秸秆还田比秸秆移除在 1m 土壤中多截留了 52.5%（27.4kgN·ha）的肥料氮（P＜0.05），同时显著提高了肥料氮收获指数并保持了籽粒产量。总的来说，与秸秆移除相比，秸秆还田显著降低了总肥料氮损失（减少 12.8%，即 14.58kgN·ha；P＜0.05）。本研究强调了秸秆还田对提高集约化种植区季节性和多季节肥料氮利用效率以及缓解肥料氮引起的环境成本的好处。
