Effects Of Deep Storage Irrigation Combined With Rainfall On Water Dynamics And Growth Of Summer Maize Field

The increase in population and climate change are affecting the hydrological and ecological processes of the region,exacerbating the contradiction between water supply and demand for agricultural production and the decrease in groundwater levels.Due to the severe uneven distribution of rainfall,there is a common problem of ineffective utilization of rainwater and flood resources in irrigation areas in arid and semi-arid regions of northern China,resulting in severe water shortage during the dry season.Overextraction of groundwater to meet water demand has caused a continuous decline in water levels,affected agricultural stability,and caused water environment deterioration.The problem is even more prominent in the Baojixia Irrigation Area in Shaanxi.Therefore,conducting a deep storage water irrigation and rainfall superposition experiment on the growth and yield of summer corn in Yangling,Shaanxi,in the hinterland of the Baojixia Irrigation District,exploring an irrigation system that fully utilizes rainwater resources to recharge groundwater without affecting yield,is of great significance for improving the efficiency of rainwater resource utilization and reducing irrigation water use in dry seasons.The paper quantitatively analyzed the effects of different regulation depths of deep storage water irrigation and rainfall superposition on the growth and development of summer maize,and obtained the following main results:(1)Revealed the regulatory effect of deep storage irrigation combined with rainfall on soil moistureAfter 10 days of deep storage irrigation in high water years,the average moisture content of each treatment in 0─100,100─200 and 0─200 cm soil layers of each treatment can reach 20.99%～27.01%,soil layers can reach 20.99%～27.01%.After 3 days of deep storage irrigation in normal water years,the average moisture content of each treatment in 0 ─ 100,100 ─ 200 and 0 ─ 200 cm soil layers can reach20.91%～28.01%.The treatment with the planned irrigation depth of 90 cm for water storage in jointing stage of summer maize in wet year had the highest field evapotranspiration,1.57%～28.13% higher than other treatments,and the evapotranspiration at the control depth of 140 cm in normal year reached the maximum,0.2%～25.42% higher than other treatments;The maximum amount of water that can be replenished to the deep soil during the full growth stage of summer corn in the year of abundant water and flat water can reach279.32 and 150.03 mm,indicating that deep water storage irrigation can store surface water in the deep soil to replenish groundwater,and also indicating the effectiveness of using rainwater and flood resources during flood season for irrigation.(2)Clarified the impact of deep storage irrigation combined with different hydrological year types on the morphological indicators of summer maizeIn rainy years,with the increase of regulation depth,the stem diameter and leaf area index showed a trend of first increasing and then decreasing.The plant height,stem diameter,and leaf area index of other treatments decreased by 0.57% to 2.98%,2.71% to21.96%,and 3.08% to 11.34% compared to the treatments with regulation depth of 60 cm,90 cm,and 150 cm,respectively.The stem diameter was more sensitive to soil moisture;As the depth of regulation increases,the stem diameter first decreases and then increases in the normal year,and the leaf area index and plant height generally show a trend of first increasing and then decreasing.The plant height,stem diameter,and leaf area index of other treatments decrease by 0.94%～5.54%,0.64%～8.22%,and 0.44%～5.39% compared to the treatment with a regulation depth of 180 cm,90 cm,and 90 cm,respectively;The relationship between dry matter accumulation and growth days of summer maize plants under deep storage irrigation and rainfall conditions was well fitted using the logistic growth equation.As the regulation depth increased,the dry matter accumulation showed a trend of first increasing and then decreasing.In high and low water years,it reached its maximum at treatment depths of 90 and 120 cm,respectively.As the depth of regulation increases,deep storage water irrigation can promote the growth of summer maize roots within a certain range.If the soil moisture threshold is exceeded,it will inhibit root respiration and thus inhibit root growth and development;The accumulation of chlorophyll in leaves shows a trend of first increasing and then decreasing with the increase of regulation depth.Choosing an appropriate water storage depth is beneficial for the photosynthesis of summer maize.(3)Obtained the characteristics of corn yield composition under deep storage irrigation,and proposed the optimal deep storage irrigation systemDuring the grouting process,the cumulative increment of 100 grains follows a parabolic curve.Deep storage irrigation can delay the arrival of the grouting peak,which is beneficial for improving the grain weight in the later growth stage and preventing the occurrence of premature aging in the later growth stage;Under deep storage irrigation treatment,the yield of summer maize in two seasons was highest at the control depth of 90 and 120 cm,respectively.Continuing to increase the control depth would result in a yield reduction of 1.05%～13.81% and 0.09%～5.69%,respectively;Deep storage irrigation is beneficial for summer maize to accumulate more aboveground biomass,but WUE decreases compared to the control group,mainly due to higher soil moisture,enhanced leaf transpiration and ground evaporation;Logistic equation can be used to fit and predict evapotranspiration,grain yield and water use efficiency under deep storage irrigation;The deep storage irrigation system with the highest comprehensive score in high and low water years corresponds to a regulation depth of 90 and 180 cm,respectively,which is conducive to the effective allocation of regional rainwater and flood resources.