小麦生产水足迹区域差异及归因分析

Spatial variability and attribution analysis of water footprint of wheat in China

用水效率评价是节水农业研究的重点领域之一。作物生产水足迹作为评价作物生产过程中水资源消耗类型、数量以及用水效率的综合指标,为农业水资源管理评价提供了全新的思路。该文基于水足迹理论和量化方法,分析了中国大陆小麦生产水足迹空间分布情况和特征,并对造成水足迹区域差异的因素进行归因分析。结果表明:小麦水足迹的空间分布差异显著,其中西北、西南局部以及华南等地的小麦水足迹较高,而黄淮海、东北东部等地的水足迹较低。新疆绿水足迹比例为11.87%,部分南方省份大于80%,绿水足迹所占比例呈现出从东南沿海向西北内陆递减的空间分布格局。归因分析结果显示除小麦品种差异外,区域农业生产水平和气候条件的差异也是造成小麦水足迹空间差异的主要原因,其中化肥、农业机械投入是影响小麦水足迹的主要农业生产因子,而太阳辐射和降水量是影响小麦水足迹的主要气候因子,该研究结果可为国家制定农业水资源管理策略提供参考。

Water use efficiency assessment is one of the core research items in water-saving agriculture. The water footprint（WF） of crop production is a comprehensive indicator reflecting water consumption types, quantities and water use efficiency during crop growth period. Based on the theory of water footprint, this study quantified and evaluated the regional differences of water footprint of wheat at the regional scale in China's Mainland. Meanwhile, in order to find the dominant factors causing the regional differences of water footprint of wheat, correlation and path coefficient analysis were used to identify the relationship between water footprint of wheat and its impact factors. The results showed that there were obvious regional differences of water footprint of wheat in China's Mainland. The water footprint of wheat was relatively low in the eastern part of Northeast China, most of Huang-huai-hai region, parts of the Lower-Middle Reaches of the Yangtze River and Sichuan province, which was less than 1 m3/kg; while the high values of water footprint of wheat were mainly distributed in Northwest China, the northwest of Inner Mongolia, the south of Lower-Middle Reaches of the Yangtze River and the south of Southwest China, which were more than 1.8 m3/kg. From the perspective of water type, the blue water footprint accounted for 49.02%, while the green water footprint accounted for 50.98% among the total WF of wheat. The green water proportion in wheat water footprint increased gradually from northern regions to southern regions. For instance, the proportion of green water footprint was 18.62% in Beijing, while it was more than 80% in most of southern regions. The regional distinction of green proportion in water footprint was in accordance with the precipitation on distribution. The region with abundant precipitation usually has a high proportion of green water in crop water footprint. There were 9 related factors selected for the attribution analysis： average temperature, relative humidity, growing season precipitation, solar radiation, wind speed, fertilizer consumption, pesticides consumption, agricultural machinery and irrigation share. The statistical analysis revealed that the regional variability of wheat water footprint, besides the crop varieties, was mainly caused by the regional disparities of agricultural production level, such as agricultural inputs and irrigation condition. On the other hands, the solar radiation and precipitation were the major climatic influencing factors causing the regional difference of water footprint of wheat. The indirect path coefficient of water footprint of wheat and its impact factors showed that solar radiation had indirect effects on water footprint through temperature, and precipitation mainly through relative humidity. Meanwhile, the fertilizer consumption, pesticides consumption, agricultural machinery power, irrigation had indirect effect on water footprint of wheat through each other influencing factors. The total influence coefficient analysis showed that the chemical fertilizer consumption, pesticides consumption, agricultural machinery and irrigation were the dominant factors that had an effect on water footprint of wheat. The results can provide information for plan-making of agricultural water management schedule.