Study On Soil Pore Characteristics And Solute Transport Under Banana Field At Different Growth Stages

The solvable rocks in Guangxi are prone to soil erosion and subsidence due to their low soil-forming capacity and barren land,which leads to the deterioration of soil structure and regulation function.This region is prone to soil erosion and settlement,which worsens the soil structure condition and its regulation functions.In order to study the soil pore structure and solute transport of the soil in a farm under banana cultivation in Guangxi,the effect of crop growth in different stage on soil pore structure and solute transport were investigated.It is beneficial to alleviate the waste of water and fertilizer input due to the extensive management mode of heavy water and large fertilizer in banana planting process in this region.Therefore,this study took banana soil as the research object,combined with CT scanning technology to obtain the number and shape of soil pores,connectivity characteristics,solute transport characteristics,and correlation analysis of banana soil at different growth stages.The obtained results show that:（1）In soil pore structure,the spatial distribution and surface density of pore in vegetative stage were better than that in seedling stage.The number of pores（2279）,specific surface area(2.78 mm^-1),and Euler number（2775）in seedling stage were higher than those in vegetative stage（14.6%、3%、33%,respectively）.Other pore characteristic parameters such as porosity（0.04%）,average diameter（1.14 mm）,connectivity（0.50）,and branch intersection number（7035）were lower than those in vegetative growth stage（33%、25%、34%,and 65%,respectively）.（2）The variation trend of biological pore parameters was consistent with the total pore structure.The overall continuity of biological pore structure in vegetative growth stage was higher than that in seedling stage.The variation of each parameter was as follows:the Euler number（16）,the number of biological pores（29）,and the specific surface area(3.57 mm^-1)at seedling stage were larger than those at vegetative growth stage（225%、10%、27%,respectively）.Other pore parameters such as porosity（0.002%）,average diameter（1.61 mm）,connectivity（0.71）,and branch intersection number（639）were lower than those in vegetative growth stage（77%、10%、23%,and 86%,respectively）.（3）The time for solute conductivity,TDS,and relative chloride concentration to reach stable value in seedling stage was longer than that in vegetative growth stage.The soil hydrodynamic dispersion coefficient(0.040 m²·h^-1)at vegetative stage was higher than that at seedling stage(0.021 m²·h^-1).The fitting results of soil penetration curve were good,and R²were all above 0.9.The hydrodynamic dispersion coefficient had a significant positive correlation with porosity,connectivity,and surface density.Moreover,a significant negative correlation with specific surface area was observed.The growth and development process of banana crops is beneficial to the improvement of soil pore structure.The soil pore structure in vegetative growth stage was better than that in seedling stage and traditional paddy field.On the one hand,the reduction of mechanical tillage reduces the influence of soil compaction on soil pore structure.It is also beneficial to the natural recovery of soil pore structure after seedling stage.On the other hand,the growth and development of banana root system can alleviate the influence of soil natural subsidence on soil pore structure.A series of biological pore structures formed by crop roots repeatedly growing and extending in the compact soil were observed which increased the soil pore volume.This had also improved the connectivity of soil pore structure,which is conducive to crop growth and drought resistance.Overall,a good soil pore structure can provide a better water conductivity and nutrient conditions in favor of crop growth and development.It is beneficial to the sustainable and healthy development of soil.