Study On Three-dimensional Distribution Characteristics Of Pore Properties And Nitrogen And Phosphorus Nutrient Contents In Vegetable Fields Based On CT Technology

This study takes different planting types of land in Wanggang Town,Yingshang County,Anhui Province as the research object,and comprehensively uses theoretical methods such as soil CT scanning technology,ordinary Kriging interpolation technology and volume distribution fractal dimension to explore the soil of different planting types.The three-dimensional characteristics of the pore structure and its relationship with the content of nitrogen and phosphorus in the soil.Three typical areas were selected in the Wanggang Town Experimental Base,namely wheat field,facility vegetable field and open vegetable field.Considering comprehensively the planting type of the test base and the distribution characteristics of ditches,three sampling points were selected in each typical area.In order to explore the relationship between soil pores and soil nitrogen and phosphorus content distribution,12 sampling points were evenly distributed in open vegetable fields,of which sampling points No.7,8,and 9 coincided with CT scanning soil sample sampling points.Soil samples of different depths of 0-20 cm,20-40 cm,40-60 cm,and 60-80 cm were taken at each site,and the nutrient content data of Olsen-P,total nitrogen,total phosphorus,p H,etc.at different depths of each site were obtained from the test.The soil pore characteristics of plots of different planting types are averaged.The number of connected pore groups in the wheat field is 830.56 groups and the total number of pores is 1038478;the number of connected pore groups in the facility vegetable field is 276.85 groups and the total number of pores is 3461.59;open vegetable fields The number of connected pore groups is 369.14 groups,and the total number of pores is 4165.46 groups.The connected pore group,the total number of pores,the average pore radius and the average length of the wheat field are all higher than that of the facility vegetable field and open vegetable field,while the open vegetable field is higher than the facility vegetable field.Analysis of the soil pore structure map reveals that the distribution of soil pores in the horizontal plane is uneven and the spatial difference is significant.The connection of the pore area is obviously diagonally diagonal,the large pores are significantly smaller and significantly aggregated,and the small pores are distributed in points around the large pores;vertical The surface pores are mainly concentrated above 30 cm in the middle and upper part of the soil column.Correlation analysis of pores and nutrients shows that the average pore radius is significantly negatively correlated with total nitrogen,and the total pore length is significantly negatively correlated with Olsen-P.It is proved that the larger the pores,the greater the loss of total nitrogen.The longer the total pore length,the higher the degree of Olsen-P loss.The volume distribution fractal dimension is used to calculate the soil fractal dimension to reflect the surface complexity of the soil particle size.The maximum value of soil fractal dimension(1.83)is located farthest from the ditch in the wheat field;the minimum value(1.59)is located farthest from the ditch in the open-air vegetable field.Comparatively speaking,the soil particle size surface of the wheat field is more complicated.The reason may be that the wheat roots are developed and the soil particle size at different levels is complicated.At the same time,the wheat field is less frequently cultivated,and less fertilizer is applied during the cultivation,and the soil is not easy to compact;In contrast,vegetable roots are shallow,open-air vegetable cultivation is more frequent,and the amount of chemical fertilizers applied is more,which is easy to cause soil compaction,resulting in simplification of the surface of the soil particle size.After analyzing the correlation between the fractal degree and the nitrogen and phosphorus nutrients,we can see that there is no direct correlation between the two.As a technical means,fractal mainly obtains the spatial self-similar structure of the soil,and the soil nutrients have no physical physical mechanism Obvious relationship.