中文摘要：

确定化肥投入强度环境安全阈值对于农业可持续发展和环境保护具有重要的意义。根据大田作物氮磷钾1：0.5：0.5（质量比,下同）的养分要求,建立氮磷钾化肥施用环境安全阈值模型,对中国化肥施用强度和环境安全阈值的时空变化及施肥合理性进行研究。结果表明：1）1980年以来中国化肥施用量迅速提高,化肥施用强度则以每年平均增长4.1%的速度上升。氮磷钾肥料比例从1980年的1：0.3：0.05,增加到2014年的1：0.5：0.43,逐渐趋于发达国家1：0.50：0.50的水平。氮磷钾肥料投入分别在1988年、2000年、2009年超过了环境安全阈值,之后差距越来越大;2）青海、西藏、甘肃、四川、贵州、江西和黑龙江属于低强度施肥区,重庆等为中强度施肥区,新疆等为高强度施肥区,海南、河南、北京、天津为超高强度施肥区;3）中国60%以上省份的化肥施用环境安全阈值在中阈值区范围变化;4）2014年中国化肥施用强度是环境安全阈值1.2倍,施用强度最高的陕西省是安全阈值的3倍,但是仍有不少省份施肥不足;氮肥、磷肥施用过量比较严重,钾肥施用不足较为普遍。各省份应根据具体情况采取不同的施肥策略,正确处理粮食安全与环境保护的关系。

英文摘要：

It is very important for the sustainable agriculture development and environmental protection to determine the environmental safety threshold of fertilizer in China.Models of fertilization environmental safety threshold were setup to study the spatio-temporal changes,reasonability of fertilization intensity and its environmental safety threshold.The results showed that：1）the fertilizer application rate had been increasing since 1980 in China.The application rate in 2014 was as about 5times as that in 1980,the fertilizer intensity in 2014 was as nearly 4 times as that in 1980,and the efficiency of fertilization decreased by 50%from 1980 to 2014.The proportion of N：P：K was from 1：0.3：0.05 in 1980 to 1：0.5：0.43 in 2014.Intensities of N,P and K fertilizer application rate started to exceed the environmental safety thresholds in 1988,2000,2009,respectively.The gaps had been increasing ever since;2）in China,the areas with low intensity of fertilization included Qinghai,Xizang,Gansu,Sichuan,Guizhou,Jiangxi and Heilongjiang,mainly distributed in the west part of China.The areas with medium intensity of fertilization included Chongqing and some others.Hainan,Henan,Beijing and Tianjin belonged to those with very high intensity of fertilization.Xinjiang and some others belonged to the high intensity fertilization area.The high and very high intensity fertilization areas were located at North China Plain and south-east coastal areas;3）There were 3types of N fertilizer environmental safety threshold regions：low threshold area（≤125 kg/hm2）,medium Nitrogen threshold region（125-165 kg/hm2）,and high Nitrogen threshold region（165 kg/hm2）.More than 60% of the studied areas in China belonged to the medium environmental safety threshold area;Qinghai,Gansu,Shannxi,Shanxi,Yunnan and Guizhou belonged to the low threshold area;Jilin,Liaoning,Shandong,Jiangsu and Xinjiang belonged to the high threshold area.The distributions of fertilization environmental safety thresholds for P and K were same as Nitro