Reducing environmental risk by improving N management in intensive Chinese agricultural systems
Reducing environmental risk by improving N management in intensive Chinese agricultural systems
复制标题
通过改善中国集约农业系统的氮肥管理来降低环境风险
DOI：
10.1073/pnas.0813417106
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发表时间：
2009-03-03
影响因子：
11.1
通讯作者：
Zhang, Fu-Suo
中科院分区：
文献类型：
--
作者：
Ju, Xiao-Tang;Xing, Guang-Xi;Zhang, Fu-Suo
我国集约化农业区过量施氮导致大气、土壤和水体富含农业源活性氮，造成严重的环境问题。本研究采用综合方法研究了中国两种最密集的两熟制的粮食产量和氮素损失途径：中国东部太湖地区的水旱稻/高地小麦与华北平原的灌溉小麦/玉米。当与基于知识的最佳氮肥节省30-60%的氮肥相比时，我们发现，目前的农业氮肥实践，每年每公顷550-600公斤的氮肥，并没有显着提高作物产量，但确实导致约2倍的氮素损失到环境中。水稻/小麦系统中氮素损失率高于小麦/玉米系统，而氮素存留率低于小麦/玉米系统，表明水稻/小麦系统对残留氮素的利用率较低。在太湖地区，周期性的水涝导致了氮素通过反硝化作用的大量损失。石灰性土壤和集中的夏季降雨导致氨挥发（19%的小麦和24%的玉米）和硝态氮淋失的主要途径在小麦/玉米系统。大气沉降和灌溉水中氮的增加超过2倍，反映了严重的空气和水污染，这些已成为农业生态系统的重要氮源。通过采用最佳氮肥施用技术、控制主要氮素损失途径和提高农业推广服务的绩效，可以在不牺牲作物产量的情况下实现更好的氮素平衡，但可以显著降低环境风险。
Excessive N fertilization in intensive agricultural areas of China has resulted in serious environmental problems because of atmospheric, soil, and water enrichment with reactive N of agricultural origin. This study examines grain yields and N loss pathways using a synthetic approach in 2 of the most intensive double-cropping systems in China: waterlogged rice/upland wheat in the Taihu region of east China versus irrigated wheat/rainfed maize on the North China Plain. When compared with knowledge-based optimum N fertilization with 30–60% N savings, we found that current agricultural N practices with 550–600 kg of N per hectare fertilizer annually do not significantly increase crop yields but do lead to about 2 times larger N losses to the environment. The higher N loss rates and lower N retention rates indicate little utilization of residual N by the succeeding crop in rice/wheat systems in comparison with wheat/maize systems. Periodic waterlogging of upland systems caused large N losses by denitrification in the Taihu region. Calcareous soils and concentrated summer rainfall resulted in ammonia volatilization (19% for wheat and 24% for maize) and nitrate leaching being the main N loss pathways in wheat/maize systems. More than 2-fold increases in atmospheric deposition and irrigation water N reflect heavy air and water pollution and these have become important N sources to agricultural ecosystems. A better N balance can be achieved without sacrificing crop yields but significantly reducing environmental risk by adopting optimum N fertilization techniques, controlling the primary N loss pathways, and improving the performance of the agricultural Extension Service.