| 摘要: |
| 旱地农田土壤被认为是重要的N2O排放源，但排放通量及影响因素仍存在不确定性。对西北干旱半干旱地区农田土壤N2O的排放分析表明，全区N2O排放通量相对较低，20世纪80 — 90年代呈波动式增长。N2O排放的空间格局总体呈现从东南向西南逐渐减少的趋势。陕西地区排放量为75.58 t ∙ a−1，贡献了全区50%的N2O排放。过量的氮肥施用、较高的降水量以及明显的增温效应是陕西南部N2O排放增强的主要原因。 |
| 关键词: 农田土壤 N2O 干旱半干旱地区 |
| DOI：10.7515/JEE201603008 |
| CSTR： |
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| 基金项目:国家自然科学基金项目（41301213）；中央高校基本科研业务费；黄土与第四纪地质国家重点实验室开放基金（SKLLQG1522） |
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| Spatial variation and influence factors of cropland N2O emission in the Northwest Arid Area |
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ZHANG Fan, WANG Zheng, LI Xuxiang1,2
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1. Department of Environmental Science and Technology, School of Human Settlements and
Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China;2. State Key Laboratory of Loess
and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
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| Abstract: |
| Background, aim, and scope Upland soil is considered as an important source of N2O emissions. At present there are many research about the field influence factors on N2O emissions. However, in traditional rainfed agricultural region of Northwest China, it still lack of in-depth discussion about how these factors affect N2O emissions synthetically at regional scale. In this study the change trend of N2O emissions and its influence factors under climate fluctuation and management change were discussed based on regional simulation to support the future prediction of change of cropland N2O emissions. Materials and methods Daily weather data for simulation were taken from the Modern-Era Retrospective Analysis for Research and Application (MERRA). Soil property data were collected form the national soil survey and the Chinese Soil Atlas. Crop parameters, fertilizer application rates were described in the database using agriclutural census data and other sources. Twenty years simulation about the N2O emissions of cropland in Northwest China were made based on these database. Results The analysis of the cropland N2O emission in arid and semi-arid areas of Northwest China show that the regional N2O flux is relatively low and reduced gradually from southeast to southwest with the decreasing precipitation and temperature overall. The lowest emissions appeared in Ningxia, which account for only 5% of total N2O emissions. Shaanxi has the highest N2O emission, accounting for 50% of the total N2O emissions of the region. There showed significant regional difference and the highest flux appeared in southern Shaanxi. Through the 20 years average N2O flux was 0.016 kgN∙hm−2·a−1 and increased fluctuantly in Nothwest China in the 1980s and 1990s. Discussion Fertilizer rate has decisive effect to the spatial distribution of N2O emissions. High N2O emissions value concentrated in southern Shaanxi and Guanzhong regions mainly due to excessive nitrogen fertilization application in these areas. In addition, this high N2O emissions could be strengthened in southern Shaanxi because of the increased soil moisture caused by higher level of precipitation. However it should also be noticed that southern Shaanxi have higher temperature and is warming fastest. The increasing of soil temperature can promote N2O emissions. Rising temperature can also promote soil water loss and inhibits N2O emission when soil moisture is too low. The influence of climate factor on N2O emissions changed according to different hydrothermal condition. Conclusions Cropland N2O emissions in the Northwest Arid Area was relatively low. N2O emissions reduced gradually from southeast to southwest. Excessive fertilization lead to high N2O emissions in southern Shaanxi. High precipitation and significant warming can further enhance N2O emissions. Recommendations and perspectives In the future strengthen the management and effective utilization of chemical fertilizer and water resource to reduce N2O emissions should be the focus of northwest dryland farming management. |
| Key words: cropland soil N2O arid and semi-arid area |
