Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan.
Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan.
Sci Total Environ. 2020 Apr 15;713:136677. doi: 10.1016/j.scitotenv.2020.136677. Epub 2020 Jan 15.
Crop residues are produced from agriculture in large amounts globally. Crop residues are known to be a source of nitrous oxide (NO); however, contrasting results have been reported. Furthermore, the effect of crop residues on nitric oxide (NO) and methane (CH) fluxes has not been well studied. We investigated NO, NO, and CH fluxes after low C/N crop residue (cabbages and potatoes) inputs to lysimeter fields for two years using with automated flux monitoring system. Lysimeters were filled with two contrasting soil types, Andosol (total C: 33.1 g kg; clay: 18%) and Fluvisol (17.7 g kg; 36%). Nitrogen application rates were 250 kg N ha of synthetic fertilizer and 272 kg N ha of cow manure compost for cabbage, and 120 kg N ha of synthetic fertilizer and 136 kg N ha of cow manure compost for potato, respectively. Large NO peaks were observed after crop residues were left on the surface of the soil for 1 to 2 weeks in summer, but not in winter. The annual NO emission factors (EFs) for cabbage residues were 3.02% and 5.37% for Andosol and Fluvisol, respectively. Those for potatoes were 7.51% and 5.10% for Andosol and Fluvisol, respectively. The EFs were much higher than the mean EFs of synthetic fertilizers from Japan's agricultural fields (0.62%). Moreover, the EFs were much higher than the Intergovernmental Panel on Climate Change (IPCC) default NO EFs for synthetic fertilizers and crop residues (1%). The annual NO EFs for potatoes were 1.35% and 2.44% for Andosol and Fluvisol, respectively, while no emission was observed after cabbage residue input. Crop residues did not affect CH uptake by soil. Our results suggest that low C/N crop residue input to soils can create a hotspot of NO emission, when temperature and water conditions are not limiting factors for microbial activity.
农作物残茬在全球范围内大量产生于农业。农作物残茬已知是一氧化二氮（NO）的来源；然而，已有报告得出了相互矛盾的结果。此外，农作物残茬对一氧化氮（NO）和甲烷（CH）通量的影响尚未得到很好的研究。我们使用自动通量监测系统，在两年内对淋溶土柱田间施入低 C/N 农作物残茬（白菜和土豆）后，调查了 NO、NO 和 CH 通量。淋溶土柱填充了两种截然不同的土壤类型，即壤土（总 C：33.1 g kg；粘土：18%）和弱淋溶土（17.7 g kg；36%）。白菜的氮肥施用量分别为 250 kg N ha 的合成化肥和 272 kg N ha 的牛粪堆肥，土豆的氮肥施用量分别为 120 kg N ha 的合成化肥和 136 kg N ha 的牛粪堆肥。夏季，农作物残茬留在土壤表面 1 至 2 周后，会出现大量的 NO 峰值，但在冬季不会出现。白菜残茬的年排放因子（EF）分别为壤土和弱淋溶土的 3.02%和 5.37%。土豆残茬的年排放因子分别为壤土和弱淋溶土的 7.51%和 5.10%。这些 EF 值远高于日本农业用地合成化肥的平均 EF 值（0.62%）。此外，这些 EF 值远高于政府间气候变化专门委员会（IPCC）对合成化肥和农作物残茬默认的 NO EF 值（1%）。土豆残茬的年排放因子分别为壤土和弱淋溶土的 1.35%和 2.44%，而白菜残茬输入后没有排放。农作物残茬没有影响土壤对 CH 的吸收。我们的研究结果表明，当温度和水分条件不是微生物活动的限制因素时，低 C/N 农作物残茬施入土壤可能会造成 NO 排放的热点。
