Optimization Of Planting Structure Based On Water Footprint At The Yellow River Pumping Irrigation Area In The Middle Arid Zone Of Ningxia

The water requirement and effective rainfall of the main crops in the middle arid zone of Ningxia were calculated by CROPWAT8.0,and the the blue water footprint and-green water footprint of main crops were calculated,and the grey water footprint was calculated based on the chemical fertilizer application amount,and the crop planting structure of the Yellow River pumping irrigation area in the middle arid zone of Ningxia was optimized based on the water footprint of each major crop and the status quo of the water resources and the status of agricultural planting in the Yellow River pumping irrigation area in the middle arid zone of Ningxia..The main results were as follows:(1)The planting structure of the arid zone in middle Ningxia was mainly based on grain crops,supplemented by economic crops,and the sown area of grain crops was much larger than the sown area of vegetables and fruits,and the proportion of food crops accounted for 77.34%of the total sown area.It was much larger than the sown area of other kinds of crops;the proportion of economic crops accounts for 22.66%of the total sowing,of which most of them were 12.36%for oil sunflowers.The sown area of food crops was too large,water was more concentrated,and water resources were under pressure.(2)From the point of view of time,the peak of crop water demand was in May,June,July and August,and the daily peak demand of wheat and melon crops was concentrated in May and June;the peak daily water requirement of maize was June and July;July and August were peak daily water demands of potato crops and oil crops;alfalfa were perennial herbaceous plants and were divided into five pods a year.This paper did not consider the wintering season and would last for one year.Divided into four pods,the peak daily water demand was mainly concentrated in four months,five months and seven months.It can be seen that most of the demand for crops and water were concentrated in July,and a few were concentrated in August.July and August were the peak periods of daily water consumption of crops other than wheat and fruit crops.(3)The blue water footprint and green water footprint were generally wavy from 2007 to 2015.When the blue water footprint was high,the green water footprint was low.This meant that when the irrigation water volume was low,the effective rainfall was high,and when the irrigation water volume was high,the effective rainfall was low.From the point of view of the composition of the water footprint,the water footprint of all types crops in the middle arid zone of Ningxia was dominated by the blue water footprint,followed by the green water footprint,and the grey water footprint only accounted for a small portion of it;from the perspective of different crop types,The proportion of wheat in blue water was the highest,the proportion of blue water was lowest,the proportion of green water was the highest,which was 30.5%,the t percentage of green water in wheat was the lowest accounted for 13.32%,the gray water footprint of maize was the highest accounted for 1.92%,and the proportion of gray water footprint of alfalfa was the lowest accounted for 0.5%.It can be seen that the amount of irrigation water required by wheat was the most,the amount of irrigation water required by alfalfa was the least,and the amount of rainfall absorbed by alfalfa was the highest,the amount of rainfall absorbed by wheat was the least.Fertilizers were most used for maize,and the fertilizer used for alfalfa was the least;from the spatial composition of the water footprint,the proportion of total blue water of Tongxin was the highest,the proportion of total blue water of Hongsipu was the lowest.The proportion of the total green water of Haiyuan was the highest,the proportion of the total green water of Hongsipu was the lowest,the proportion of the total grey water of Haiyuan was the highest,and the proportion of the total grey water of Hongsipu was the lowest;from the unit mass water footprint,potato>wheat>oil crops>alfalfa>maize>vegetables>fruits,which showed a good yield of maize,vegetables and fruits,unit quality water footprint of wheat in Hongsipu was the lowest;The unit quality water footprint of maize in Haiyuan was the lowest,whose green water accounts for the highest proportion;the unit quality water footprint of potato crops in Hongsipu was the lowest,but the proportion of green water in Haiyuan was the highest;the unit quality water footprint of maize in Hongsip was the lowest,but the proportion of blue water was high.Although Haiyuan’s potato crops have higher water footprints per unit quality,the blue water accounted for the lowest proportion;the unit quality water footprint of the melons and fruits in Hongsipu was high,but the proportion of blue water is high,and the proportion of green water in Haiyuan was the highest.The raw water quality of vegetables in Haiyuan was the lowest,green water accounted for the highest proportion,followed by Hongsipu.The crop water footprint in the middle arid zone was constantly changing with changes in farming practices,irrigation methods and planting area.It was necessary to combine the actual conditions of farmland to strengthen water-saving irrigation construction,standardize water management,improve agronomic practices,and increase irrigation water use efficiency to achieve water-saving production.(4)The optimization resulted that the planting areas of the seven crops have changed than before.The planting area of maize,potato,oil crops and green fodder have been reduced to varying degrees compared with those before optimization.Planting area of wheat,fruit and melons,vegetables increased to varying degrees;the total water footprint decreased by 0.75×108m3/a;the total economic benefit increased from the 1.649 billion to 2.461 billion,an increase of 738 million;the total ecological benefit was 48.42 million Yuan increased to 48.47 million yuan,an increase of 246100 yuan;saving water resources of 23700 m3,It was necessary to promote rational planning of water resources,develop efficient water-saving agriculture,and promote the sustainable development of agriculture.