Effects Of Ridge–furrow Mulching System And Supplemental Irrigation On The Yield And Water Use Efficiency Of Summer Maize Under Different Planting Densities

The semi-humid and drought-prone areas in Northwest China are short of agricultural water resources,and agricultural water use efficiency is relatively low.In order to further improve the utilization rate of natural precipitation and reduce the amount of irrigation while maintaining crop yields,this study took summer maize in the irrigated farming area of Guanzhong as the research object.In the 2019 and 2020 summer corn growing seasons,Zhengdan 958 was used as the test material at the Doukou Wheat-Maize Comprehensive Experimental Station of Northwest A&F University,and set up 2 kinds of planting densities(L:60,000 plants ha^-1;H:75,000 plants ha^-1)as the main area factor,and 2 kinds of planting methods（R:Ridge–furrow mulching system;F:conventional flat cropping）and 2kinds of irrigation measures（S:Supplemental irrigation;f:flooding irrigation）are arranged randomly,which is a sub-regional factor.Discuss the influence of furrow and ridge rainwater harvesting and moisture measurement supplemental irrigation technology under different densities on soil water dynamics,water consumption characteristics,crop population growth,yield and its constituent factors,water use efficiency and economic benefits of summer corn farmland.The following research results have been obtained:（1）At the same density,RS significantly increased the soil water content and soil water storage of 0-80cm soil layer compared with FS and Ff treatments before irrigation,but was not significantly different from Rf treatment.After irrigation in the jointing period（V10）,in the later growth period（tasseling period-mature period）RS treatment has no significant difference in soil water content compared with Rf,FS and Ff treatments under 80-200cm soil layer,and the total water consumption and soil water storage consumption of RS treatment are significantly lower than Rf,FS and Ff treatments;Under the same planting method and irrigation method,the soil moisture content of the 0-200cm soil layer under the H treatment was significantly lower than that under the L treatment.In addition,whether in normal water years and rich years,low and high densities have little effect on water consumption during the whole growth period of summer corn.Therefore,RS treatment has a better effect on increasing soil water content and reducing total water consumption,and different densities have no significant effect on soil water status.（2）At the same density,RS treatment can significantly increase summer maize leaf area index and above-ground dry matter accumulation compared with FS and Ff treatments,and the difference is not significant compared with Rf.At the same time,the former has a higher difference in the normal years（2019）than in the wet years（2020）;Under the same planting method and irrigation method,the leaf area index and the dry matter accumulation of the aerial part of the H treatment were significantly higher than that of the L treatment.Therefore,RS and Rf treatments are beneficial to increase summer maize leaf area index and dry matter accumulation above the ground,and the combined H treatment has a better effect.（3）At the same density,the yield and yield components of RS treatment are significantly higher than that of FS and Ff treatments,and the difference is not significant compared with Rf.This rule is more obvious in the normal years（2019）than in the wet years（2020）.At the same time,the increase in yield is mainly due to the increase in grain number per spike in normal water years,and the increase in yield is mainly due to the increase in 100-kernel weight in wet years;Under the same planting method and irrigation method,the H treatment can significantly increase the grain yield than the L treatment（11.80-34.11%）,and increase the number of grains number in rows and grains number per spike.Therefore,the RS and Rf treatments have a better effect on increasing the yield and yield components,and the combined H treatment has a better effect.（4）At the same density,RS treatment can significantly increase summer maize water use efficiency compared with Rf,FS and Ff treatments,with an average increase of 28.80%,21.53%and 32.76%;Compared with RS and Rf treatments,FS and Ff treatments have lower precipitation utilization efficiency,and this rule is more obvious in normal water years;In different precipitation years,the irrigation water use efficiency of RS treatment was 3.18,1.23 and 3.26 times that of Rf,FS and Ff treatments on average;Under the same planting method and irrigation method,the water use efficiency of each treatment under the H treatment was higher than that of the L treatment,and the RS treatment under the H treatment is significantly higher than that of Rf,FS and Ff treatments.Therefore,in terms of water use efficiency,precipitation use efficiency,and irrigation use efficiency,RS treatment has a better effect,and the combination of H treatment has the best performance.（5）In different precipitation years,due to more precipitation in the wet year（2020）,the number and quantity of irrigation are greatly reduced,and the net income of total input and production investment are significantly higher than in the normal year（2019）;At the same density,the total income of RS and Rf treatments is 0.11-0.52 million ha^-1more than that of FS and Ff treatments,and the O/I and NI are significantly higher than the FS and Ff treatments;The net income of RS treatment is not significantly different from that of Rf treatment,but the irrigation volume of Rf treatment is about three times that of RS treatment.Although the economic benefits are the same,the latter is not conducive to saving water resources;Under the same planting method and irrigation method,The O/I and NI of H treatment are significantly higher than that of L treatment（19.28%-73.53%）.The NI data from 2019 to 2020 showed that RS treatment under H treatment is 10,700 yuan ha^-1and 17,700 yuan ha^-1respectively,which are higher than other treatments in the year,and the economic benefits are the best.In summary,at a planting density of 75,000 plants ha^-1,ridge–furrow mulching system combined with supplemental irrigation techniques can improve soil moisture status,promote summer corn growth and development,significantly increase summer corn grain yield,improve crop water use efficiency and economic benefits while reducing the amount of irrigation.Therefore,in the semi-humid and drought-prone areas of Northwest China,the planting model can be used as a water-saving,high-yield and high-efficiency planting technique in the semi-humid and drought-prone areas of Northwest China.