中国农田氮肥投入和生产效率

过去40年,中国氮肥用量增加、氮肥效率下降引起了国内外普遍关注,但中国不同作物氮肥用量及其利用效率缺乏大样本数据研究。本文通过农户调查及文献资料,对1970~2009年,尤其是从2000到2009年,中国主要农作物施氮量(化肥氮)、产量、氮效率(氮肥偏生产力)进行了研究。与2000~2003年相比,2008~2009年粮食、蔬菜、果树平均氮肥用量增加,单产增加,氮效率提高。粮食、蔬菜、果树氮肥用量分别增加26、36、107 kg/hm~2,产量分别增加1 280、5 722、18 802 kg/hm~2,氮效率分别增加2.2、6.6、25.2 kg/hm~2。东北、华北和长江中下游三大粮食作物主产区的氮效率都显著提高,而西北、西南和华南等地没有提高。与2000~2003年相比,2008~2009年中国平均氮效率的上升主要是因为单产大幅提高,而非氮肥用量下降。中国粮食作物单产较低,而氮肥用量高,未来在稳定氮肥投入的情况下继续提高单产是增效的主要途径。中国蔬菜和果树氮投入量太高,应该加强管理降低氮肥用量。

Nitrogen fertilizer input and nitrogen use efficiency in Chinese farmland

In the past forty years, the rapid increasing of nitrogen fertilizer consumption and the decrease of nitrogen use effi-ciencies ( NUE) in China have attracted the worldwide attention. The basic data and researches on the nitrogen fertilizer input and NUE in different crops are still quite limited in China. In this paper, data were collected through farmer survey and data mining were used to evaluate nitrogen fertilizer input status, grain yields and nitrogen partial factor productivity ( PFPN ) of crops nationwide in the past forty years, especially during the last decade. The results showed that the average nitrogen fertilizer input, yield and PFPN of grain crops, vegetables and fruits were all increased from 2008 to 2009, compared to the av-erages from 2000 to 2003. For example, the N applied rates in grain crops, vegetables and fruits were increased by 26, 36, 107 kg/hm2 respectively, the corresponding yield increases were 1 280, 5 722, 18 802 kg/hm2 respectively, leading to the values increase of PFPN of 2. 2, 6. 6, 25. 2 kg/hm2 respectively. Compared to the averages from 2000 to 2003, the values of PFPN of grain crops were increased significantly in the main grain production regions from 2008 to 2009, such as in the North-east China, North China Plain and Yangtze River Region, not in the other regions including the Northwest China, Southwest China and South China. The main reason for the PFPN increases in grain crops was the increased grain yields, not the reduce of nitrogen fertilizer comsumption. For grain crops, maintaining the presesnt N rate and increasing production are essential for improving NUE. The great potential to reduce nitrogen fertilizer input was in vegetables and fruits.