我国主要粮食作物秸秆还田替代化学氮肥潜力

基于最新农业统计资料和文献数据,分析了2013—2017年我国不同省份和不同农区主要粮食作物秸秆氮养分资源量及还田当季替代化学氮肥的潜力,为秸秆还田条件下的化学氮肥替代和减施提供科学依据。结果表明,我国主要粮食作物种植区域水稻、小麦和玉米秸秆年均产量分别为2.3亿、1.7亿t和3.9亿t,所含氮养分资源量分别为209万、108万t和356万t。三大粮食作物秸秆氮养分资源主要分布在华北、长江中下游和东北农区,分别占全国总量的31.6%、25.4%和24.2%。其中,水稻秸秆氮养分资源主要分布在长江中下游农区(120.9万t);小麦秸秆氮养分资源主要分布在华北农区(66.6万t),玉米秸秆氮养分资源集中分布于华北农区(142.1万t)和东北农区(132.5万t)。水稻秸秆还田化学氮肥可替代量较大的省份为江苏、湖北、浙江、湖南、辽宁和安徽,为34.6～46.5 kg·hm(~-2);小麦秸秆还田化学氮肥可替代量较大的省份为河南、河北、山东、安徽、江苏和新疆,为22.2～27.4kg·hm(~-2);玉米秸秆还田化学氮肥可替代量较大的省份有吉林、辽宁、内蒙古、宁夏、黑龙江、山东、江苏、新疆、湖南和安徽,为54.3～70.7 kg·hm(~-2)。在秸秆全量还田的情况下,我国水稻、小麦和玉米秸秆还田当季化学氮肥可替代总量分别为99万、54万t和192万t,化学氮肥可替代量分别为33.6、23.4 kg·hm(~-2)和51.2 kg·hm(~-2)。我国主要粮食作物秸秆氮养分资源量巨大,在秸秆还田化学氮肥替代潜力较大的地区,合理利用秸秆氮养分资源是实现化学氮肥减量的重要途径。

Nitrogen resource quantity of main grain crop straw in China and the potential of synthetic nitrogen substitution under straw returning

In this research, the nitrogen resource quantity of main grain crop straw and the potential of synthetic N substitution were estimated for different provinces and agricultural regions of China during the 2013-2017 period, based on the latest agricultural statistics and data published in the literature. The purpose of this research is to provide a scientific basis for synthetic N substitution and reduction under straw returning. Results indicated that the amounts of straw from rice, wheat, and maize in the main grain crop-planting areas of China were 230.06 million, 166.85 million, and 386.98 million tons per year, respectively. The amounts of straw N resources from rice, wheat, and maize were 2.09 million, 1.08 million, and 3.56 million tons per year, respectively; these were mainly distributed across north China, the middle and lower Yangtze River areas, and northeast China, and accounted for 31.6%, 25.4%, and 24.2% of the total national straw N resources, respectively. The straw N resources from rice and wheat were mainly distributed in the middle and lower Yangtze River areas(1.21 million tons) and north China (0.67 million tons), respectively. The maize straw N resource was mainly distributed in north China(1.42 million tons) and northeast China(1.33 million tons). In the main rice-cultivating provinces of China, the amounts of synthetic N substituted by rice straw incorporation per unit area of arable land were higher(34.6~46.5 kg·hm^-2) in Jiangsu, Hubei, Zhejiang, Hunan, Liaoning, and Anhui. The amounts of synthetic N substituted by wheat straw incorporation per unit area of arable land were relatively higher(22.2~27.4 kg·hm^-2) in Henan, Hebei, Shandong, Anhui, Jiangsu, and Xinjiang. The amounts of synthetic N substituted by maize straw incorporation per unit area of arable land were higher(54.3~70.7 kg·hm^-2) in Jilin, Liaoning, Inner Mongolia, Ningxia, Heilongjiang, Shandong, Jiangsu, Xinjiang, Hunan, and Anhui. In terms of the total straw returned to the fields, the amounts of synthetic N substituted by straw from rice, wheat, and maize could reach 0.99 million, 0.54 million, and 1.92 million tons per year, equivalent to 33.6, 23.4, and 51.2 kg·hm^-2 of per unit area of arable land, respectively. Therefore, straw N resources were plentiful in China during this period. Making full use of straw N resources from the main grain crops could provide an effective solution for the reduction of synthetic N in China''s croplands.