Effects Of Four Planting Patterns On Water Consumption And Water Use Efficiency Of Crops In Hebei Plain

Hebei Plain is a major grain producing area in China,The planting model of winter wheat-summer corn rotation is the traditional planting mode in the region,however the growth period of winter wheat(early October to the end of may in the second year)is in the dry season of the region,its irrigation water demand is relatively large,accounting for about 70%of the total irrigation water in the Hebei Plain.Hebei Plain is also an area where the contradiction between supply and demand of water resources is prominent and surface water resources are scarce.As the groundwater supply exceeds 70%of the total water supply,the groundwater is overexploited.From 1990 to 2010,the annual over-exploitation volume exceeded 6 billion m3.Under the guidance of the state and Hebei province's policies of water saving,curbing over-exploitation of water resources,adjustment of supply structure and market demand,a variety of planting modes have appeared in the Hebei Plain.This paper aims at four planting models,including winter wheat-summer corn,cotton-spinach,two-season silage corn and fallow,in 2018?2019,conducting community trials and Hydrus-1D numerical simulation research,by analyzing the soil moisture distribution,water consumption and deep leakage of these four different planting modes,the planting modes that help to conserve groundwater and contribute to ecological restoration in the Hebei Plain are explored while ensuring crop yields.The results show that:(1)In the experimental year,the irrigation water consumption of the three planting modes,winter wheat-summer corn,cotton-spinach,and two-season silage corn,were 330.7,210.5,and 266.2 mm,respectively.Compared with the winter wheat-summer corn rotation model,the irrigation water consumption of cotton-spinach and two-season silage corn cultivation models was reduced by 36.3%and 19.5%,respectively.Under the cotton-spinach and two-season corn storage model,the soil moisture content changed less than the winter wheat-summer corn rotation model.The water consumption of cotton-spinach and two-season green corn models is 16.0%and 12.0%lower than that of winter wheat-summer corn rotation,respectively.(2)Under the conditions of the four planting modes,the water consumption of the four planting modes of winter wheat-summer corn,cotton-spinach,two-season silage corn and fallow in the experimental year were 769.67,646.54,677.04 and 433.25 mm,respectively.The water consumption of the fallow mode accounts for 56.3%of the winter wheat-summer corn rotation mode.(3)In the experimental year the water use efficiencies of the three planting models,winter wheat-summer corn,cotton-spinach,and two-season silage corn were 20.65,38.78,and 87.80 kg/(hm2·mm),respectively.In the cotton-spinach and two-season green corn models,the output of spinach and green corn is the fresh weight of the whole plant so the water use efficiency of the crop is higher,which is 87.8%and 325.2%higher than the winter wheat-summer corn rotation model,respectively.The deep-leakage of cotton-spinach,two-season silage corn and fallow tillage models were 66.9%,23.1%and 81.0%less than that of winter wheat-summer corn rotation,respectively.(4)The results of Darcy's law analysis and HYDRUS-1D numerical simulation show that the deep seepage of the four planting models of winter wheat-summer corn,cotton-spinach,two-season silage corn and fallow in the experimental year are 79.19,26.22,60.92 and 15.03 mm,respectively.The deep-leakage of cotton-spinach,two-season silage corn and fallow tillage models were 66.9%,23.1%and 81.0%less than that of winter wheat-summer corn rotation,respectively.All in all,the current cotton-spinach and two-season silage corn planting models in Hebei Province not only contribute to the reduction of irrigation water consumption and crop water consumption,but also to the improvement of water use efficiency.In terms of water consumption,the fallow model may not be a better model.It may be better to choose a rain-fed mode suitable for crops.Limited by the experimental conditions and research funding,this article only conducted a preliminary discussion on the water consumption of crops of different planting patterns at the test plot scale,which requires further research and discussion on field scale experiments.