The Growth Water Footprint Of Main Food Crops In North China And Suitable Water Planting Research

The shortage of water resources and water pollution restrict the food production and social development in China.North China is an important grain-producing area in China,but agricultural water demand is large and non-point source pollution is serious,making the shortage of agricultural water resources continue to be serious.Improving the utilization efficiency of agricultural water resources and controlling non-point source pollution are important measures to effectively alleviate the current situation of agricultural water resource shortage and ensure China's food security.It is necessary to estimate and evaluate the consumption of water resources and pollution of water environment caused by crop growth,and explore the current situation of water-suitable cultivation of crops,and find the improvement suggestions and measures to reduce the irrigation water demand(blue water)and the water resources occupied by diluting pollutants(grey water).In order to provide technical support and decision-making reference for efficient utilization of agricultural water resources,prevention and control of non-point source pollution and rational distribution of food crops.Taking the prefecture-level administrative region as the basic analysis unit,using the water footprint theory to estimate the growth water footprint of wheat and maize crops in north China from 2000 to 2017.Focus on the spatial and temporal variation of growth grey water footprint and its relationship with influencing factors.Build planting suitability evaluation index,in view of the blue water consumption and blue water consumption,the grey water occupation two water use situation,respectively evaluate suitable water planting of wheat and maize in different cities and propose the optimal direction of planting layout.After joining grey water,explore the adjustment and reduction of crop planting area under the control of total agricultural water consumption.Finally,suggestions are put forward to reduce the blue water and grey water in order to realize efficient utilization of agricultural water resources and sustainable development of agricultural production.The main results are as follows:1.The grey water footprint of the main grain crops is 0.35 m3/kg of wheat was higher than 0.32 m3/kg of maize,the growth grey water footprint of both shows a fluctuating downward trend.It indicates that the effect of N fertilizer application on water resource occupation is gradually reduced.By analyzing the effects of nitrogen application and yield per unit area on lime water footprint,the following improvement directions were put forward:(1)Nitrogen application,wheat should strive to reduce nitrogen application in the plains of Beijing,Tianjin and Hebei,Hebei should focus on Shijiazhuang,Qinhuangdao and Tangshan;Maize should be reduced in the plains of Jiangsu,Tianjin and Beijing.Jiangsu should focus on Lianyungang and Xuzhou.(2)Yield per unit area,wheat should increase the yield of Beijing,Tianjin and Jiangsu plains;Maize should increase the yield of Tianjin and Henan plains.2.Irrigation water(blue water)is the main source of wheat growth,and natural precipitation(green water)is the main source of maize growth.The blue water footprint of wheat is about 1.5 times that of green water,and that of com is about 1.8 times that of blue water.Between the same crop different area,green,blue water footprint difference is bigger.It is of great significance to improve the utilization efficiency of water resources to plant crops suitable for water.3.The suitability evaluation index of suitable water planting was constructed,and the suitability of planting zones were divided into high,medium and low suitable zones by considering the blue water demand and the blue water proportion index.The areas with higher planting suitability of wheat and maize are concentrated in Anhui and Jiangsu,with sporadic distribution in Henan and Shandong,where it is recommended to improve water efficiency and expand crops planting scale.4.After further consideration of grey water,where planting suitability declines,wheat has Zhengzhou,Pingdingshan,Zhoukou,Xinyang,Xinxiang in Henan,maize has Luohe,Shangqiu,Zhoukou,Xinyang,Zhumadian in Henan,Huaibei,Bengbu,Huainan in Anhui and Suqian in Jiangsu.The decrease of suitability indicates that grey water in this area has a great negative effect on planting suitability,which is necessary to reduce the grey water footprint.5.Based on the principle that irrigation water consumption does not increase,the current irrigation water consumption is taken as the red line of total agricultural water consumption control.Based on the two analysis methods of blue water demand and blue water demand plus grey water occupation,the planting area scale of administrative wheat and maize at different levels in north China is explored.The results showed,wheat planting area was reduced from 14.48 to 8.35 million hectares,a decrease of 42%and maize planting area reduced from 11.77 to 6.35 million hectares,a decrease of 46%.The innovation of this paper is reflected in the following aspects:1.Taking the prefecture-level administrative region as the basic analysis unit,explores regional differences in the relationship between grey water footprint and various influencing factors.2.The suitability evaluation index of suitable water planting was constructed to define the suitable area,potential development area and unsuitable area for suitable water planting of main grain crops,and the planting layout optimization direction was proposed.In the two analysis methods of blue water demand and blue water demand plus grey water occupation,the changes of planting suitability and planting bearing capacity of crops in various regions were explored.3.Based on the consideration of blue water consumption and the addition of grey water,the planting area reduction of main grain crops based on the total water consumption and the mitigation measure is discussed.