Ding Weixin, Cai Yan, Cai Zucong, Yagi Kazuyuki, Zheng Xunhua
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Sci Total Environ. 2007 Feb 15;373(2-3):501-11. doi: 10.1016/j.scitotenv.2006.12.026. Epub 2007 Jan 16.
N2O emissions from a maize-wheat rotation field were monitored in the Fengqiu State Key Agro-Ecological Experimental Station (Fengqiu County, Henan Province, China) from June 2004 to June 2005. The experiment included four treatments: a bare (crop-absent) soil treated with 150 kg N ha-1 (WN150) and soils fertilized with 0 (N0), 150 (N150), and 250 (N250) kg N ha-1 and cropped with maize or wheat. The bulk of the N2O emissions occurred in pulses following the application of fertilizer N at soil temperatures of 15 degrees C or more. The application of fertilizer N significantly increased the N2O emission, from 636 g N2O-N ha-1 year-1 in the N0 treatment to 4480 g N2O-N ha-1 year-1 in the N250 treatment. However, this increase primarily occurred during the maize growing season. The emission factor of applied fertilizer N as N2O was 1.05-1.34% and 0.24-0.26% during the 105-day maize and 241-day wheat growing seasons, respectively, and was on average 0.61-0.77%. Increasing the rate of fertilizer application increased the emission factor during the maize growing season. The presence of maize appears to increase N2O emission by 45% versus bare soil during the maize growing season. And, N2O emission during the maize season were significantly related to CO2 production (R=0.43-0.81, n=30, P<0.05). N2O emission was greatly affected by soil moisture during the maize growing season and by soil temperature during the wheat growing season. The maximum rates of nitrification occurred when soil moisture was in the range of 45-60% WFPS, with the optimum value being approximately 50%. However, soil moisture influenced N2O emission only when the soil temperature was at the optimum level. It is suggested that reducing the application rate of basal fertilizer N during the maize growing season could decrease N2O emission.
2004年6月至2005年6月，在中国河南省封丘县的封丘国家重点农业生态试验站，对玉米-小麦轮作田的一氧化二氮（N₂O）排放进行了监测。试验包括四种处理：一种是施用150千克氮/公顷的裸地（无作物）土壤（WN150），以及分别施用0（N0）、150（N150）和250（N250）千克氮/公顷肥料并种植玉米或小麦的土壤。大部分N₂O排放在土壤温度15℃及以上时施肥后的脉冲期发生。施用氮肥显著增加了N₂O排放，从N0处理的636克N₂O-N/公顷·年增加到N250处理的4480克N₂O-N/公顷·年。然而，这种增加主要发生在玉米生长季节。在105天的玉米生长季和241天的小麦生长季，施用氮肥作为N₂O的排放因子分别为1.05 - 1.34%和0.24 - 0.26%，平均为0.61 - 0.77%。增加施肥量会增加玉米生长季的排放因子。在玉米生长季，与裸地相比，玉米的存在似乎使N₂O排放增加了45%。而且，玉米季的N₂O排放与二氧化碳产生显著相关（R = 0.43 - 0.81，n = 30，P < 0.05）。玉米生长季的N₂O排放受土壤湿度影响很大，小麦生长季受土壤温度影响很大。硝化作用的最大速率发生在土壤湿度为45 - 60%田间持水量范围时，最佳值约为50%。然而，土壤湿度仅在土壤温度处于最佳水平时才影响N₂O排放。建议在玉米生长季降低基肥氮的施用量以减少N₂O排放。
