The Influence Of Different Tillage Methods And Depths On Soil Pore Characteristics Of Sugarcane Fields In Guangxi

To investigate the effects of different tillage methods and tillage depths on the soil pore structure of sugarcane fields,three treatments of Rotary tillage into 20 cm depth(X20),Fenlong tillage into 20 cm depth(F20)and Fenlong tillage into 40 cm(F40)were set up in the sugarcane field of Guangxi in this study.Indoor physical and chemical properties were measured.And the soil pore structure was comprehensively analyzed by CT scanning imaging and three-dimensional imaging algorithm.The results show that:(1)Compared with the F20 treatment,the X20 treatment had a higher degree of refinement in the mechanical composition of soil particles and showed greater soil bulk and organic matter content.The soil water content and saturated hydraulic conductivity of the X20 treatment were significantly higher than those of the F20 treatment by 10.84% and 21.26% in the 0-20 cm soil layer,respectively.However they were reduced by 18.78% and 18.26%,respectively,in the 30-40 cm soil layer compared to the F20 treatment.With the increase in the depth of the Fenlong,the degree for refinement of the mechanical composition of soil particles in the whole soil profile of 40 cm depth increased in the F40 treatment compared with the F20 treatment.The saturated hydraulic conductivity and organic matter content increased by 18.71% and 2.70%,respectively,in F40 treatment comparing with the F20 treatment.Furthermore the soil bulk density in the F40 treatment decreased by 2.44%compared with the F20 treatment in the 20-40 cm soil layer.(2)Compared to the F20 treatment,the X20 treatment significantly increased the quantity of 2D pores at different particle size levels in the soil.The total 2D pore number and pore surface density in the X20 treatment were significantly higher than those of F20 treatment by 58.10% and 74.16%,respectively,while the pore complexity and rounding rate were lower than those of F20 by 9.64% and 2.91%,respectively.As the increase in the depth of the Fenlong,the number of two-dimensional pores at all ranks in the F40 treatment showed a substantial increase,which showed such phenomenon that the total number of two-dimensional pores was 106.19% times greater than that in the F20 treatment.Meanwhile the F40 treatment significantly increased the pore surface density of the soil and reduced the pore complexity and rounding rate in the 0-20 cm soil layer.(3)Compared with the F20 treatment,the X20 treatment significantly increased the quantity of 3D pores in different particle size classes.the number of 3D total pores.Soil porosity,averaged branch length and branch length density were significantly higher in the X40 treatment than those of the F20 treatment by 27.19%,74.51%,8.37% and 52.18%,respectively.But the connectivity and global connectivity were significantly lower in the X40 treatment than those of the F20 treatment by 32.55% and 43.78%,respectively.The quantity of 3D pores at all ranks in the F40 treatment increased significantly compared with the F20 treatment as the depth of the Fenlong increased.It induced that the number of total 3D pores,porosity,averaged branch length and density,connectivity and global connectivity all increased significantly in the F40 treatment comparing to the F20 treatment.The chart of three-dimensional pore distribution showed that the quantity of punctate pores in the F20 treatment were significantly less than that in the X20 treatment from 0 to 20 cm depth,in which there were a few large pores with elongated shapes in both soils.In 20-40 cm depth,the quantity of punctate pores and long-shaped pores in the F20 treatment were significantly more than that in the X20 treatment.The long-shaped pores were significantly thicker and longer in the F20 treatment than that in the X20 treatment.The quantity of punctate pores in the F40 treatment were obviously greater than that of F20 treatment in 0-20 cm depth,which showed more connective pores in the former treatment.In 20-40 cm depth,the quantity of punctate pores and long-shaped pores in both treatments were not significantly difference.However,the long-shaped pores of F40 treatment showed scattered distribution in all directions,which could promote the root development and nutrient uptake by the roots compairng to only vertical distribution of long-shaped pores in the F20 treatment.In conclusion,the Fenlong tillage is more beneficial to the growth of sugarcane than the rotary tillage,furthermore the increased depth of Fenlong could promote the formation of appropriate pore structure in Guangxi.