Effects Of Subsoiling On Soil Structure And Water Use In Wheat-Maize Crop System

This test was conducted in Lai-yang City,Shandong Province at the anniversary of winter wheat-summer maize growth in 2018-2019.Three treatments were set up,contrasting with rotary tillage（RT）,subsoiling tillage in summer（ST-S）,and subsoiling tillage in autumn（ST-A）.Among them,the depth of the rotary tillage treatment was 15 cm,and the depth of the subsoiling tillage was 35 cm.Study the effects of different subsoiling stage treatments on the structure of the soil layer,the stability of aggregates,the content of organic carbon,the water use efficiency and crop yields.And determining the most reasonable stage of subsoiling,with a view to determining the popularization and operable rational cultivation layer construction technology will promote soil improvement and increase crop yield.The findings are as follows:1.Effect of subsoiling on soil structure and SOC contentsubsoiling tillage can improve the soil layer structure.Compared with RT,the average soil bulk density of ST-S and ST-A at 10-40 cm has been reduced by 5.36%and 5.77%,respectively,and the soil compaction of soil layers below 30 cm has been significantly reduced.The solid phase is reduced,the liquid phase is increased,and the gas phase is increased.Subsoiling can construct a more ideal soil three-phase structure,which makes the soil plow layer structure more reasonable.Different subsoiling stage affects the distribution of soil water-stable aggregates at various levels.Compared with RT,subsoiling can better protect the stability of soil surface aggregates.ST-S and ST-A can significantly improve the stability of 0-20 cm.The number of large agglomerates(R_0.25).In soil layers below 20 cm,the particle size of subsoiling treatment aggregates gradually decreased,and the number of large agglomerates gradually decreased.Subsoiling in summer and subsoiling in autumn can significantly increase the soil organic carbon content of each soil layer,which is conducive to improving the soil’s carbon sequestration capacity and providing a suitable soil environment for crop growth.2.Effect of subsoiling on crop yield and carbon footprintCompared with RT,the annual yields of wheat and maize in ST-S and ST-A increased by8.52%and 13.08%,respectively,significantly increasing wheat and maize yield.Two types of subsoiling stage have different effects on the yield of summer maize,and ST-A has a better effect on maize yield.Under the wheat-maize system,subsoiling can reduce the annual carbon cost.The specific grain carbon cost is expressed as:ST-A>ST-S>RT.The annual economic benefits of ST-A processing are the highest.3.Effect of subsoiling on water use efficiencySubsoiling can construct a reasonable plow layer and promote efficient water use,and it can significantly increase the moisture content of deep soil in farmland.Compared with RT,ST-S and ST-A significantly improve the field water holding capacity of 20-40 cm soil layer.The combination of deep and loose built plow layer can increase soil infiltration performance and increase disturbance to deep soil,the stable infiltration rate of this treatment improves the soil’s ability to retain water and soil,expands the capacity of soil reservoirs,and improves WUE.Subsoiling can increase the economic benefit of wheat-maize production anniversary,and the annual economic benefit of ST-A treatment is the highest.To sum up,in the winter wheat-summer maize growth anniversary,compared with RT,the combination of deep and loose tillage construction effectively improved the soil tillage layer structure.Both types of subsoiling stage can improve the soil structure and enhance the reunion.Body stability,increase soil organic carbon content.Subsoiling promotes efficient use of soil water,builds stable soil reservoirs to improve water storage capacity,rationally regulates the spatial distribution of soil water,and improves WUE.Both ST-S and ST-A can increase annual crop yields,of which ST-S significantly increases wheat production but no significant increase in maize production,ST-A can significantly increase wheat maize production and reduce carbon emissions per unit of output.Both Subsoiling stages have a better effect on soil structure,but ST-A treatment can achieve higher crop yields and WUE and lower food carbon costs.Combining the various indicators of the anniversary of crop growth,ST-A can construct a more reasonable plough layer and obtain higher yields and benefits.