【作者】 王桂良；

【导师】 张福锁； 崔振岭； 陈新平；

【作者基本信息】 中国农业大学 ， 植物营养学， 2014， 博士

【摘要】 探索协调农学、经济和环境友好的农业可持续发展道路,对保障粮食和资源环境安全具有重要意义。但是当前缺乏对区域尺度农田活性氮损失与氮肥利用率定量化研究。本文在文献数据的收集结合多年多点田间试验结果的基础上,明确我国三大粮食作物区域活性氮损失特征和影响因素,以及建立活性氮损失的估算模型,最后了解区域农田氮肥利用率情况及其影响因素。取得的主要结果如下：1.全国主要粮食作物农田N淋洗损失最大,N2O排放损失最小。N淋洗(水稻包括径流)损失量和损失率分别为27.2kg N ha-1和12.6%,NH3挥发损失量和损失率分别平均为20.7kg N ha-1和11.2%,N20排放损失量和损失率平均为1.86kg N ha-1和1.0%。2.活性氮损失区域间差异显著。N2O排放损失途径中：南方冬小麦损失较大,损失量和损失率分别为3.46kg N ha-1和1.92%。N淋洗(水稻包括径流)损失途径中：长江流域单季稻、华北冬小麦和夏玉米的损失较大,损失量分别为16.8、34.1和58.3kg N ha-1,损失率分别为4.5%、15.6%和124.9%。NH3挥发途径损失中：华南晚稻、南方冬小麦和华北夏玉米较大,损失量分别为54.9、13.1和15.0kg N ha-1、损失率分别为35.2%、9.2%和8.5%。3.小麦和玉米中,N20排放和N淋洗损失随着施氮量和氮盈余的增加都呈现指数上升的趋势,NH3挥发随施氮量增加呈直线上升关系。在估算N20排放和N淋洗过程中,基于施氮量估算的活性氮损失比基于氮盈余估算的结果偏高,特别在产量和效率较高水平下,两者差异更大。因此用氮盈余模型估算N20排放和N淋洗损失,用施氮量估算NH3挥发量较为合理。小麦和玉米中表明,基于根层氮素实时监控的优化施氮措施比农民习惯的施氮量分别低60%和39%,产量分别高5%和6%,氮肥利用率分别高146%和98%,同时分别减少单位籽粒活性氮损失量80%和45%。4.农学优化施氮量指获得最高产量时的施氮量；经济优化施氮量指获得经济效益最高时的施氮量；生态优化施氮量指综合考虑了经济和环境成本,当净效益最高时的施氮量。河南小麦生态优化施氮量为201kg N ha-1,相对于经济优化施氮量(225kg N ha-1),单位籽粒活性氮损失降低了15%,而产量没有显著性变化。玉米中,比较经济优化施氮量237kg N ha-1,生态优化施氮量平均为185kg N ha-1,单位籽粒活性氮损失降低了27%,产量没有显著性变化。生态优化施氮量随着增产量的增加而增加。5.近20年来,我国水稻,小麦和玉米氮肥利用率呈现先下降后上升的趋势。1990-1999,2000-2005,2006-2010年段平均氮肥利用率分别为35%,27%和34%。其中水稻3个年代段平均氮肥利用率分别为37%,28%和37%;小麦分别为34%,28%和35%；玉米分别为35%,26%和30%。水稻中以北方单季稻氮肥利用率最高为40%；南方冬小麦最高为38%；玉米以东北春玉米氮肥利用率最高为32%。更多还原

【Abstract】 Developing ecologically optimal nitrogen management integrating agronomic, economic, and environmental aspects is urgent to ensure national food security and protect resources and environment. However, there is shortage of quantitative analysis of reactive nitrogen losses and nitrogen use efficiency of major crops in China at regional scale.In this study, based on collecting literature data and field experiments fro several years, we focus on reactive nitrogen losses (Nr) of major cereal crops in different regions and their influence factors, the development and application of empirical model for estimating reactive nitrogen losses. Finally, we comprehensive understand nitrogen recovery efficiency of major crops in China at regional scale and the influence factors. The main results were concluded as follows:1. N leaching was the highest and N2O emission was the lowest for major cereal crops. Cross major cereal crops, N leaching loss and rate were average27.2kg N ha-1and12.6%, NH3volatilization loss and rate were average20.7kg N ha-1and11.2%, N2O emission loss and rate were average1.86kg N ha-1and1.0%. N2O emission losses and rate were the highest as2.68kg N ha-1and1.49%for wheat, N leaching losses and rate were the highest as47.6kg N ha-1and20.8%for maize, NH3volatilization losses and rate were the highest as35.2kg N ha-1and17.2%for maize,2. There was great variation of Nr losses in different regions. For N2O emission, single rice in Yangtze river basin and winter wheat in south of China were the highest, N2O emission were1.89and3.46kg N ha-1, N2O emission loss rate were0.84%and1.92%. There was no significant difference of N2O emission among different regions for maize. For N leaching, single rice in Yangtze river basin and winter wheat, summer maize in North China Plain were the highest, N leaching were16.8,34.1and58.3kg N ha-1, N leaching loss rate were4.5%,15.6%and24.9%. For NH3volatilization, late rice in southern China, winter wheat in south of China and summer maize in North China Plain were the highest, NH3volatilization were54.9,13.1and15.0kg N ha-1, NH3volatilization loss rate were35.2%,9.2%and8.5%.3. Both N2O emissions and N leaching increased exponentially with the N application rate or N surplus, while NH3volatilization increased linearly with the N application rate. Estimated Nr losses were higher by N-R than those estimated by the N-S, especially for high-yield, high-REN systems. Across on-farm experimental of wheat and maize in North China Plain, an in-season root-zone N management strategy with a60%and39%lower N application rate and5%and6%higher grain yield increased the REN by146%and98%and reduced Nr loss intensity (based on the N-S) by80%and45%compared to farmers’ typical N practices for wheat and maize, respectively.4. For winter wheat in Henan province, compared with economically optimal N rate as225kg N ha-1, ecologically optimal N rate was201kg N ha-1, Nr losses intensity decreased15%without yield losses. For summer maize, compared with economically optimal N rate as237kg N ha-1, ecologically optimal N rate was185kg N ha-1, without yield losses. Ecologically optimal N rate significantly increased with the increase in N-increased yield.5. The nitrogen recovery efficiency (REN) of major cereal crops decreased from1990-1999as35%to2000-2005as27%and then increased to34%in2006-2010. For rice, REN were37%,28%and37%in the three years. For wheat, REN were34%,28%and35%in the three years. For maize, REN were35%,26%and30%in the three years. There was great variation of REN in different regions. For rice, REN of single rice in north China was the highest as40%. Winter wheat was the highest as38%. The order of REN for maize in size was Northeast China (32%)> summer maize in North China Plain (29%)> maize in Southwest China (25%).更多还原