氮循环与中国农业氮管理  

Nitrogen Cycling and Management Strategies in Chinese Agriculture

作　　者：王敬国[1] 林杉[1] 李保国[1] 

机构地区：[1]中国农业大学资源与环境学院/植物-土壤相互作用教育部重点实验室,北京100193

出　　处：《中国农业科学》2016年第3期503-517,共15页Scientia Agricultura Sinica

基　　金：国家自然科学基金重点项目(41230856,51139006);国家科技支撑计划(2012BAD15B01)

摘　　要：作为全球活性氮制造量和氮肥消费量均最大的国家,中国农业生态系统的氮平衡问题受到了国内外广泛的关注。普遍认为中国农田施氮过量问题突出,并产生了严重的环境污染。为全面了解中国农业生态系统氮的来源和去向,找出引起氮肥消费量高的原因,本研究运用氮循环基本原理,以2010年为例,根据近年来发表的文献和国家统计资料,详细讨论了不同空间尺度上中国农业生态系统的氮输出和输入,重点分析了作物-土壤系统氮循环与氮平衡的特征。2010年中国农业生态系统氮投入总体上过量,其数量基本上相当于经生物地球化学循环返回作物–土壤系统的氮量,大致在5 Tg N左右。在全国水平上,2010年化肥和有机肥带入农田的氮量,相等于作物吸氮量和农田氮损失量之和;由于化学氮肥流向的多样化,如林、牧、渔业和城市绿化等的氮肥消耗,以及部分经济作物包括果树和蔬菜,特别是设施蔬菜的高量施氮,总体上粮食作物过量施氮的问题并不十分突出。在耕地资源有限(占全球8%的耕地面积,养活20%的世界人口)、有机废弃物中氮养分循环利用率低于30%、豆科作物播种面积较少且生物固氮占农田总氮投入不足15%的情况下,中国的农业生产只有依靠氮肥。然而,中国氮肥消费存在着很大的地区差异,在土地生产力水平较高的黄淮海、长江中下游和珠江三角洲地区,单位农作物播种面积的施氮量显著高于全国平均水平。这些地区氮肥消费量较大与粮食单产高、复种指数高和豆科作物种植比例低有密切关系。因此,为保证人们不断增长的食物需求和膳食结构的改善,加之土壤基础肥力相对较低,农田化学氮肥投入较高具有一定的合理性。然而,农业生产过程中发生的氮损失,既浪费了资源,也污染了环境。损失进入大气和水中活性氮以及环境中新产生的活性氮,经生物地球�It is in general thought that nitrogen （N） fertilizer is overused in Chinese croplands and that the overuse has resulted in severe environmental problems. As the biggest reactive nitrogen producer and N fertilizer consumer in the world, China is facing a great challenge to reduce nitrogen consumption in agriculture. The objectives of this review are to examine the sources and fate of reactive nitrogen in agroecosystems, to find out why N fertilizer consumption reaches such a high level, and provide with suggestions for better N management practices. To understand the current agricultural use of reactive N in China, principles of biogeochemical N cycling are used to discuss N flows in the agroecosystems in the year 2010, with focus on N input/output and balances in crop-soil systems. At the national level, input of reactive N to croplands was excessive in 2010, and the surplus was approximately equal to the quantity of the reactive N recycled back to crop fields by atmospheric N deposition and irrigation with N-polluted water, about 5 Tg N. Generally speaking, the use of N fertilizer in cereal crops is not extraordinarily high since N fertilizer is also distributed for other uses： Forestation, feeding livestock and fishes, and application to the green fields in urban areas. It is common and significant that there are much higher N application rates to fruit tree plantations and vegetable production, especially to the greenhouse vegetable growing system, in comparison with that applied to cereal crops. With the facts of the limited arable lands, low recycling rates of organic wastes, and low input of biological fixed N, crop production has to depend heavily on the use of N fertilizer in China. There is a low acreage of arable land per capita, with 8% of global arable land feeding 20% of the world population. Recycled rate of nutrient N in the organic wastes are lower than 30% and input of biological N fixation to croplands is less than 15%. Therefore, to meet the demands of Chinese population for both food an

关 键 词：农业生态系统 氮生物地球化学循环 氮平衡 氮损失 氮管理 

分 类 号：S181[农业科学—农业基础科学]