title: Characteristics of N2O production and transport within soil profiles subjected to different nitrogen application rates in China.
abstract: 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.
authors.affiliation: 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.
authors.forename: Weige
authors.initials: W
authors.lastname: Nan
authors.affiliation: 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.
authors.forename: Shanchao
authors.initials: S
authors.lastname: Yue
authors.affiliation: 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. Electronic address: sqli@ms.iswc.ac.cn.
authors.forename: Shiqing
authors.initials: S
authors.lastname: Li
authors.affiliation: Northwest A&F University, Yangling 712100, China.
authors.forename: Haizhou
authors.initials: H
authors.lastname: Huang
authors.affiliation: 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.
authors.forename: Yufang
authors.initials: Y
authors.lastname: Shen
keywords: Cumulative amount; Fluxes; N(2)O concentration; Nitrogen fertilization; Season