Direct emission factor for N₂O from rice–winter wheat rotation systems in southeast China

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• 作者：Jianwen Zou ; Yao Huang ; Yanyu Lu ; Xunhua Zheng and Yuesi Wang
• 关键词：N₂O ; Emission factor ; Background emission ; Fertilizer ; Crop residue
• 刊名：Atmospheric Environment
• 出版年：2005
• 期刊代码：11_13522310
• 类别：env
• 出版时间：2005
• 卷：39
• 期：26
• 页码：4755-4765
• 文件大小：419 K

摘要

A field experiment was conducted in a rice–winter wheat rotation agroecosystem to quantify the direct emission of N₂O for synthetic N fertilizer and crop residue application in the 2002–2003 annual cycle. There was an increase in N₂O emission accompanying synthetic N fertilizer application. Fertilizer-induced emission factor for N₂O (FIE) averaged 1.08%for the rice season, 1.49%for the winter wheat season and 1.26%for the whole annual rotation cycle. The annual background emission of N₂O totaled 4.81 kg N₂O–N ha⁻¹, consisting of 1.24 kg N₂O–N ha⁻¹ for rice, 3.11 kg N₂O–N ha⁻¹ for wheat seasons. When crop residue and synthetic N fertilizer were both applied in the fields, crop residue-induced emission factor for N₂O (RIE) was estimated as well. When crop residue was retained at the rate of 2.25 and 4.50 t ha⁻¹ for each season, the RIE averaged 0.64%and 0.27%for the whole annual rotation cycle, respectively. Based on available multi-year data of N₂O emissions over the whole rice–wheat rotation cycle at 3 sites in southeast China, the FIE averaged 1.02%for the rice season, 1.65%for the wheat season. On the whole annual cycle, the FIE for N₂O ranged from 1.05%to 1.45%, with an average of 1.25%. Annual background emission of N₂O averaged 4.25 kg ha⁻¹, ranging from 3.62 to 4.87 kg ha⁻¹. It is estimated that annual N₂O emission in paddy rice-based agroecosystem amounts to 169 Gg N₂O–N in China, accounting for 26–60%of the reported estimates of total emission from croplands in China.