Potential And Gap Of Yield And Water Productivity Of Wheat-maize Under Different Irrigation Systems In Hebei Plain

In view of the shortage of water resources in Hebei plain and the serious over exploitation of groundwater,which restrict the production of wheat and maize in this area,the water productivity needs to be improved.The wheat and maize production of typical farmers in piedmont plain and Heilonggang low plain were investigated,and the actual yield and irrigation water productivity of farmers were calculated.Combined with the crop model(APSIM)simulation method,the potential yield and potential irrigation water productivity of wheat-maize double cropping system in Hebei Plain were simulated.This paper analyzes the gap of water productivity and the factors influencing the gap,it provides a scientific basis for improving the water productivity of farmers.The main results and conclusions are as follows:(1)The results of farmer survey show that the annual irrigation frequency of wheat-maize in Hebei Plain is 4-5.Level of farmers in Piedmont Plain,the annual average yield(Ya)is 15771.53 kg/hm2,and irrigation water productivity(IWPa)is 3.51 kg/m3.Level of farmers in the Heilonggang low plain,The average annual yield(Ya)is 15535.90 kg/hm2,and irrigation water productivity(IWPa)is 3.26 kg/m3.(2)Simulation of wheat-maize system double cropping under suitable sowing date and different irrigation levels.The results show that when the annual irrigation amount is 375 mm(M2W4,75mm for wheat sowing+75mm for jointing+75mm for flowering+75mm for maize sowing+75mm for flowering),the annual maximum yield(Yh)is 22156.63 kg/hm2,annual irrigation water productivity(IWPyh)of wheat-maize in Piedmont plain is 5.91 kg/m3.Compared to farmers,the gapof annual yield is 6385.10 kg/hm2,the gapof irrigation water productivity is 2.40 kg/m3.The annual maximum yield(Yh)of wheat-maize in Heilonggang low plain is 21454.73 kg/hm2,and the annual irrigation water productivity(IWPyh)is 5.72 kg/m3.Compared to farmers,the gap ofyield in wheat-maize is 5918.83 kg/hm2,and the gap of irrigation water productivity is 2.46 kg/m3.(3)The simulation of different wheat sowing dates scenrios shows that the average annual yield(Ys)of wheat-maize under unsuitable sowing date in the Piodmont plain is 21703.95 kg/hm2,and the irrigation water productivity(IWPs)is 5.79 kg/m3.Compared with the suitable sowing date,the annual yield gap(Ygs)caused by sowing date is 452.68 kg/hm2,and the irrigation water productivity gap(IWPgs)is 0.12 kg/m3.The other gaps are caused by irrigation,the yield gap(Ygw)caused by irrigation management measures is5932.42 kg/hm2,and the irrigation water productivity gap(IWPgyh)is 2.28 kg/m3.In Heilonggang low plain,the average annual yield(Ys)under unsuitable sowing dateis 20081.07 kg/hm2,and the irrigation water productivity(IWPs)is 5.35 kg/m3.Compared with the suitable sowing date,the annual yield gap(Ygs)caused by sowing date is 1373.66kg/hm2,and the irrigation water productivity gap(IWPgs)is 0.37 kg/m3.The other gaps are caused by irrigation,the yield gap(Ygw)caused by irrigation management measures is4545.17 kg/hm2,and the irrigation water productivity gap(IWPgyh)is 2.09 kg/m3.(4)According to the current water supply situation in Hebei Plain,the analysis results of annual yield and irrigation water productivity under different irrigation scenarios show that:when the irrigation amount is 225mm,the irrigation water productivity is the highest(M1W1,75mm for wheat sowing+75mm for jointing+75mm for maize sowing).In the scenario,the annual yield(Yih)of wheat-maize in Piedmont Plain is 19845.91 kg/hm2,and the maximum irrigation water productivity(IWPh)is 8.82 kg/m3.In Heilonggang low plain,the annual yield(Yih)of wheat-maize is 19734.80 kg/hm2,and the maximum irrigation water productivity(IWPh)is 8.77 kg/m3.In conclusion,under the wheat-maize double cropping system in Hebei Plain,through the implementation of relevant water management measures,farmers can obtain higher irrigation water productivity,which is of great significance to promote the regional food production and water sustainable development.When the highest annual yield is obtained,the annual irrigation water productivity of farmers can be increased by 40.61%～43.01%;when the highest annual irrigation water productivity is obtained,the annual irrigation water productivity of farmers can be increased by 53.51%～62.83%.