Study On The Stability And Wettability Of Soil Aggregates With Different Particle Sizes

Soil aggregate is the basic unit of soil structure,which is an important index reflecting the stability,fertility and quality of soil structure.Wettability reflects the relationship among matter at the solid-liquid-gas interface,and characterizes the spreading ability or tendency of a liquid on a solid surface;the wetting of soil particles by water is the core mechanism of soil water relationship and water movement.This paper takes Lou soil and brown soil with good structure and loess soil with poor structure as the research objects,the stability and wettability of soil aggregates with different particle sizes were measured by High Energy Moisture Characteristics(HEMC)method and capillary rising method respectively,In order to have a further understanding of the stability mechanism of soil aggregates.The main conclusions are as follows:(1)Rapid wetting can make soil aggregates reach pseudo saturation state quickly,it leads to the decrease of pseudo saturated water content and the increase of residual water content.Rapid wetting will produce air explosion effect of air compression,which will lead to the disintegration of soil aggregates,while slow wetting may be mainly caused by the expansion of clay minerals.With the increase of wetting rate,the stability of aggregates decays in a power function.(2)In structural soil,the decrease of aggregate size leads to the increase of water content in soil water holding curve and the right shift of specific water capacity curve.The aggregates with 0.25 ～ 0.5mm and 0.5 ～ 1mm particle size have higher stability;There was a negative correlation between soil aggregate stability and organic matter content in the range of 1 ～ 2 mm and 0.25 ～ 0.5 mm,and a positive correlation between soil aggregate stability and organic matter content in the range of 0.5 ～ 1 mm;It is possible that the mechanism of cementation of aggregates with different diameters is different.(3)In non structural soil,the particle sizes of soil aggregates with high stability are0.25～0.5 mm.There was a positive correlation between the stability of soil aggregates and the content of organic matter under the particle size of 1～2mm and 0.5～1mm,while there was a quadratic relationship between the stability of soil aggregates and the content of organic matter under the particle size of 0.25～0.5mm.(4)The contact angle of soil aggregates decreases with the increase of soil particle size;In the range of 0.5 ～ 1 mm(non structural soil)and < 0.25 mm particle size,the contact angle of soil aggregates was positively correlated with the content of soil organic matter,while in the range of 0.25 ～ 0.5 mm particle size,the contact angle of soil aggregates was negatively correlated with the content of soil organic matter,In the range of 1 ～ 2mm particle size,when the contact angle is less than 53° The soil contact angle increased with the increase of organic matter content,When the contact angle is greater than 53 ° The soil contact angle decreased with the increase of organic matter content.