Effects Of Different Water Supplies In Growth Period On Winter Wheat And Comparison Of Water Consumption Between Cropland And Orchard Under The Conditions Of Equal Total Water Supply On The Loess Tableland

In the Southern Loess tableland area,winter wheat is the main food crop,and mainly cultivated by dry farming mode.Soil water storage at sowing stage and precipitation in growth period constitute the water source for growth and development of winter wheat.Field experiments of winter wheat was carried out to study the effects of soil water storage before sowing and supplemental irrigation(simulate different precipitation conditions)on the yield,water consumption(ET)and water use efficiency(WUE)under the same water supply condition.They will provide a basis for the selection of management measure for high and stable yield of dry winter wheat.In this area,the productivity of cropland has improved a lot and large areas of cropland were transformed into orchards.Through the long-term soil water observational experiment of unfertilized cropland,fertilized cropland and 13 years apple orchard,the soil moisture characteristics and dynamic changes of cropland and orchard under the equal precipitation supply condition were compared and analyzed,and the water consumption difference between them were quantified.Further,this study analyzed the dynamic of soil water storage and the characteristics of recharge during the fallow period of unfertilized and fertilized cropland to discussing the impact factors of precipitation storage efficiency(PSE).The main results are as follows:1.At the early stage of vegetative growth of winter wheat,the number of tiller can be improved by increasing soil water storage before sowing.When soil water storage at sowing stage was low,the adverse effect of insufficient soil moisture can be eliminated by irrigation at standing stages,and the number of productive spike will increase.The ET of CK treatment was slightly higher than other treatments,and irrigation period had no significant effect on water consumption.There was no significant difference of WUE between all of treatments and the WUE of CK was the lowest,and the high irrigation treatment was slightly higher than other treatments.Under the same water supply condition with soil water storage before sowing and supplemental irrigation,the water supply at standing stage and booting stage can exert the same effect as equal soil water storage before sowing.The effect of irrigate at the grain-filling stage was related to soil water storage before sowing,the effect was weakened when soil water storage before sowing was low and irrigation amount was high.For the management of dryland cropland,the key to increase the yield and WUE was focus on soil water storage and preservation in summer fallow period and restrain the evaporation loss of soil moisture in growth period.2.The layers of dry-wet alternation were appears in different depths under different land use patterns.The depth of unfertilized cropland、fertilized cropland and 13 years apple orchard were 0-220,0-160 and 0-140 cm respectively.The deep soil moisture fluctuated slightly and exhibited a certain temporal stability.The soil water storage always showed unfertilized cropland> fertilized cropland> orchard in one year,and the dynamic of 3 sample plot were consistent.After soil water balance in one year,the soil water storage increased slightly in cropland,while it decreased slightly in orchard during the trial period.Soil desiccation were found in the three sample plot,and the 13 years orchard formed a stable dry soil layer which thickness was more than 5 meters.In the Loess tableland area,long-term and effective measures of soil water storage and preservation should be promoted to increase the preservation and utilization of precipitation in cropland and orchard.3.The soil water recharge in fallow period of cropland was affected by precipitation,evapotranspiration,initial soil water storage and other factors.During the summer fallow period,several years observation was shown that the precipitation storage efficiency of unfertilized cropland and fertilized cropland were 33% and 40% respectively.During the winter fallow period,the evapotranspiration of unfertilized cropland was higher than that of fertilized cropland.There was a positive correlation between PSE of fertilized cropland and precipitation in summer fallow period.With the increase of precipitation,the difference of PSE between unfertilized and fertilized cropland increased gradually.The initial soil water storage in summer fallow period can also affect PSE.The evapotranspiration increased 0.76 mm with initial soil water storage increased 1mm,and the PSE increased with the increase of soil water deficit.