Improvement Of Soil Structure And Water Holding Capacity Of Calcareous Purple Soil By Deep Vertical Rotary Tillage

The purple soil hilly area has the advantages of good light and heat conditions,rich nutrients,and moderate texture,but the disadvantages of shallow soil layer,small water capacity,and poor drought tolerance limit the exertion of its many advantages.The purple soil parent rock is soft and rapidly weathered.Obtaining the soil matrix from the parent rock is a fast and effective way to increase the water-holding space.In this study,the technical advantages of deep ploughing without disturbing the soil layer of the powder ridge machine were combined with the unique softness of the purple soil parent rock,indoor analysis and model analysis combined research methods to study the effect of deep vertical rotary tillage on soil water infiltration and water holding capacity,and then propose a drought resistance and flood drainage method based on integrated soil and parent rock tillage.The main results and conclusions of this study are as follows:（1）Effects of deep vertical rotary tillage on soil physical properties and soil structureThe deep vertical rotary tillage crushed the loose shale can not only achieved a rapid increase in soil thickness to more than 60 cm,but also decreased soil bulk density（13.96%～72%less than conventional tillage）and soil compaction（22.3%～91.3%less than conventional tillage）and increased soil porosity（43.41%～69.67%larger than conventional tillage）for a long time after tillage.The above results showed that the deep vertical rotary tillage can effectively increase the thickness of the soil layer by breaking the parent rock,and improve the soil physical properties and soil structure.（2）Effects of deep vertical rotary tillage on soil moisture transportThe indoor soil simulated infiltration test showed:With the increase of 30%gravel content,the stable infiltration rate was the smallest（0.06 cm/min）,and the stable infiltration duration was the maximum（324 min）.Field in situ soil infiltration experiments showed that the initial infiltration rate,stable infiltration rate and average infiltration rate of deep vertical rotary tillage were 16%～41%,83%～186%and 173%～190%higher than those of conventional tillage,respectively.The above results showed that deep vertical rotary tillage to break the parent rock promoted water infiltration and increased soil water infiltration capacity.（3）Effects of deep vertical rotary tillage on improving water holding capacityDeep vertical rotary tillage significantly increased soil water content and soil water storage.The maximum increase in soil water content was 63.69%.Compared with conventional tillage,upslope soil water storage increased by 125.69%and 66.02%,while downslope tillage increased by 34.99%and 6.58%.There were no significant difference in soil water storage capacity between different slope positions in the deep vertical rotary tillage treatment,indicating that the deep vertical rotary tillage increased the soil water storage capacity on the upper slope to the same as that on the downward slope.The deep vertical rotary tillage crushed the shale,thickens the soil（substrate）layer,increased the water storage matrix,expanded the water capacity of the slope,stores rainwater on site,and improved the water receiving and holding space and storage capacity.