State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, China; Northwest A&F University, Yangling 712100, China.
Sci Total Environ. 2016 Jan 15;542(Pt A):864-75. doi: 10.1016/j.scitotenv.2015.10.147. Epub 2015 Nov 8.
To better understand the effect of N fertilizer on the responses of subsoil N2O to N2O emissions in a high-yield plot, we investigated the subsurface N2O concentrations at seven mineral soil depths and analyzed the subsoil N2O fluxes between soil horizons. This study was conducted from 2012 to 2013 in farmland located in the semi-humid area of the Changwu station, Shaanxi, and the results showed that the application of N fertilizer triggered the highest amount of N2O production and effluxes in the various soil layers. With an increase of N fertilizer, N2O effluxes and production significantly increased; the mean variation of 380 kg N ha(-1) treatment was much greater than that of 250 kg N ha(-1) treatment, particularly after fertilization during the maize growing season (MS). N2O concentrations increased within 30 cm and maintained low and stable values. However, N2O fluxes and production decreased with depth (below 30 cm) and then remained low (approximately zero or even negative) at depths of 30-90 cm. The cumulative N2O fluxes in the 0-15 cm soil layer accounted for 99.0% of the total amount in the soil profile, and high fluxes coincided with periods of relatively high production rates. The cumulative production of N2O also remained in step with the cumulative fluxes. In addition, more N fertilizer was applied, greater production occurred in the topsoil. A significantly positive relationship was found between N2O fluxes and mineral N, and a negative relationship was found between the fluxes and the water-filled pore space (WFPS) in the shallow soil. N2O effluxes increased with increasing amounts of N fertilizer, which was primarily due to nitrification on the Loess Plateau.
为了更好地理解氮肥对高产田土壤剖面 N2O 对 N2O 排放响应的影响，我们在 7 个矿质土层中调查了亚表层 N2O 浓度，并分析了土壤层间的亚表层 N2O 通量。本研究于 2012 年至 2013 年在陕西长武站半湿润地区的农田中进行，结果表明，氮肥的施用在各个土层中引发了最大量的 N2O 产生和排放。随着氮肥用量的增加，N2O 通量和产生量显著增加；380kgNha-1 处理的平均变化量比 250kgNha-1 处理的大得多，尤其是在玉米生长季（MS）施肥后。N2O 浓度在 30cm 内增加，并保持低而稳定的值。然而，N2O 通量和产生量随深度（30cm 以下）下降，然后在 30-90cm 深度保持低值（接近零甚至为负）。0-15cm 土壤层中的累积 N2O 通量占土壤剖面总量的 99.0%，高通量与相对较高的产生率时期相一致。N2O 的累积产生也与累积通量保持一致。此外，施用更多的氮肥，表层土壤中产生更多的 N2O。N2O 通量与矿质 N 呈显著正相关，与浅层土壤的充水孔隙空间（WFPS）呈负相关。N2O 通量随氮肥用量的增加而增加，这主要是由于黄土高原的硝化作用。
