Temporal And Spatial Distribution And Efficient Utilization Of Annual Moisture In The Drip Irrigated Wheat-silage Corn Double Cropping System In Northern Xinjiang

With the continuous adjustment of the agricultural structure,the drip irrigated wheat and silage corn double cropping system was widely spread and applied in the northern Xinjiang area.Up to 2015,it over 20000 hm2.In arid and semi-arid regions,the annual precipitation in Xinjiang is less than 200 mm,and the evaporation volume is more than 1000 mm.If a large amount of drip irrigated wheat-silage corn double cropping pattern is carried out it will be bound to increase pressure on agricultural water resource.In order to get more particular knowledge of water consumption characteristics of drip irrigated wheat-silage maize double cropping system,achieve timely and proper water supply,save water resource and improve the utilization efficiency of water resource,this research,based on the local meteorological data,was carried out to explore the spatio-temporal distribution characteristics of soil water content,the reference crop evapotranspiration in the area,ET0,and its relations to the primary meteorological factors,the evapotranspiration,ET,the crop coefficient,K,and effects on the crop yield,water use efficiency and economic benefit of drip irrigated wheat and silage corn double cropping system,by setting two factors,irrigation amount and frequency,in three levels differently.The results shows as below.(1)The temporal and spatial distribution of soil water in drip irrigated wheat and sila ge corn double cropping system: In this experiment,In spring wheat at the tillering join ting stage,grain filling stage and booting stage,the water consumption of silage corn in the jointing and sucking stage,the soil moisture decreased obviously.In the replant ing system of drip irrigated wheat and silage corn,the soil moisture fluctuation is mai nly concentrated in the 0—60cm soil layer.High frequency irrigation will aggravate th e fluctuation of soil moisture in the 10 cm soil layer.Under the condition of high irrig ation,the maximum water fluctuation of high frequency irrigation is 0.135,the water fl uctuation of middle and low frequency irrigation is 0.146 and 0.143 respectively.Unde r the condition of low irrigation,the minimum water fluctuation of high frequency irri gation is 0.127,The soil water content of drip irrigated wheat and silage corn double cropping system was reduced,and the consumption of soil water storage was smaller under high irrigation,and the soil water consumption was the largest under the medi um irrigation and medium frequency treatment.(2)The relationship between Reference Crop Evapotranspiration,ET0,and meteorological factors in "drip irrigated wheat and silage corn" double cropping system: ET0 was affected by some meteorological factors.In general,ET0 value was smaller in April,May,Sept.and October,while it was larger in June,July and August in the "drip irrigated wheat and silage corn" double cropping system.In detail,ET0 was positively correlated with the highest temperature,the lowest temperature and the average temperature,but it wasnegatively correlated with relative humidity.So in the calculation of ET0 accumulation of drip irrigated wheat-silage maize double cropping system,it can be simplified by the single accumulate meteorological data.When the meteorological data is not complete,we can also accurately estimate the accumulation ET0 through this method in the drip irrigated wheat and silage corn multiple cropping system.(3)Effects of different irrigation amount and irrigation frequency on ET and K value of drip irrigated wheat and silage corn double cropping system: the variation range of evapotranspiration,ET,and crop coefficient,K value,of wheat in Northern Xinjiang was respectively in 354 mm-471.58 mm,0.8431-1.1128,while the ET and K value of silage maize was in the range of 200.48 mm-355.36 mm,0.5879-1.0421.The value of ET and K were mainly affected by the irrigation volume.With the increase of irrigation volume,ET and K values were ever-increasing.Effects of irrigation frequency on ET and K values varied with different irrigation amounts.(4)The effect of different irrigation and irrigation frequency on drip irrigated wheat and silage corn double cropping system: the yield of wheat and silage corn under the medium irrigation was higher,the yield of wheat was between 6537.58 kg·hm-2-7837.97 kg·hm-2,and the yield of silage corn was between 19417.29.58 kg·hm-2-22348.58 kg·hm-2;Under the condition of irrigation,the yield of wheat and silage corn is low,the yield of wheat in each frequency is between 3229.76 kg·hm-2 and 4423.17 kg·hm-2,and the yield of silage corn is between 13890.8 kg·hm-2 and 15945.6 kg·hm-2.Under the condition of high irrigation,the yield of wheat and silage corn is the least,and the yield of Wheat is 5925.38 kg·hm-2 silage.The yield of maize was 17071.7 kg·hm-2,and the yield of wheat and silage corn under low irrigation was lower than that of middle and low frequency treatment.The yield of wheat and silage corn decreased by 28% and 13.8% in the silage corn.Under the same irrigation volume,the water use efficiency of each frequency was mainly affected by yield.The higher the yield was,the greater the water utilization rate was.The water use efficiency of silage maize was mainly influenced by water consumption under different irrigation amounts.The lower the water consumption was,the greater the water utilization rate was.Under the experimental conditions,irrigation rate of wheat was 300 mm,drip irrigation 5 times,silage corn 220 mm irrigation amount and drip irrigation 3 times.