Soil Physical Properties And Erodibility In Typical Salt Lakes

Soil salinization is a global ecological problem.Because of the high salt content in soil,soil properties deteriorate and land productivity decreases.Therefore,people attach great importance to its restoration,development and utilization.Soil physical properties and erodibility are important indicators to reflect the quality of soil properties.It is of great significance to improve the properties of salinized soil and increase its productivity to understand the changes of physical properties and erodibility of salinized soil and the influencing factors.Salt lakes are widely distributed in our country,the high level of soil salinization around them,which makes them an important reserve land resource for arable land.However,the changing characteristics and influencing factors of soil physical properties and erodibility in salt Lake area are not well understood.Therefore,in this paper,the non-rhizosphere and rhizosphere soil near Huamachi Salt Lake and Chaka Salt Lake in Dingbian were taken as the research object,and the particle composition,microaggregate composition and stability characteristics of the rhizosphere soil of 0-30cm non-rhizosphere soil,and the rhizosphere soil of two dominant species(Salicornia europaea and Kalidium foliatu),the water holding capacity of surface soil and soil erodiability were studied.In addition,the changes of soil particle composition,micro-aggregate composition and stability,soil water holding capacity and soil erodibility under different salinity and alkali levels as well as their influencing factors were explored,in order to provide reference for saline-alkaline soil remediation in the Salt Lake region.The main research results are as follows:(1)Salt and alkali had a certain effect on the particle composition of non-rhizosphere soil,but had no effect on the particle composition of rhizosphere soil.In non-rhizosphere soil,particle size<0.002 mm and 0.002-0.02 mm increased with the increase of saline-alkali degree,while particle size 0.02-0.05 mm,0.05-0.25 mm and 0.25-2 mm decreased with the increase of saline-alkali degree.The contents of different particle sizes in rhizosphere soil did not change with the increase of salinity.The fractal dimension of non-rhizosphere soil particles was between 2.687-2.756,and increased with the increase of saline-alkali degree.The fractal dimension of rhizosphere soil particles was between 2.705-2.716 and did not change with the increase of salinity.Under saline-alkali conditions,non-rhizosphere soil particle composition and fractal dimension were significantly correlated with soil nutrients,while rhizosphere soil particle composition and fractal dimension were not significantly correlated with soil nutrients.Therefore,non-rhizosphere soil particle composition and fractal dimension could better reflect the change of soil properties under saline-alkali conditions.(2)Salt and alkali can affect the composition and stability of microaggregates in non-rhizosphere soil,but have little effect on the composition and stability of microaggregates in rhizosphere soil.In the non-rhizosphere soil of the study area,the content of microaggregates with particle size of 0.05-0.25 mm was the highest(28.91%-36.27%),and the content of microaggregates with particle size of 0.25-2 mm was the least(2.55%-3.64%).With the increase of salinity,the particle size of 0.002-0.02 mm and0.02-0.05 mm was significantly increased,while the particle size of 0.05-0.25 mm and0.25-2 mm was significantly decreased,and the fractal dimension of the microaggregates was gradually increased,while the MWD and GMD were significantly decreased,and the stability of microaggregates was gradually weakened.In the rhizosphere soil of the study area,the content of microaggregates with particle size of 0.05-0.25 mm was the highest(31.97%-34.20%),and the content of microaggregates with particle size of 0.25-2 mm was the least(4.61%-5.57%).However,with the increase of salinity,The content of microaggregates with different particle sizes did not change significantly(except those with particle sizes of 0.02-0.25mm),nor did the fractal dimension,MWD and GMD of microaggregates.Under saline-alkali conditions,the main factors affecting the composition and stability of non-rhizosphere soil microaggregates include soil particle composition and organic carbon content,while the main factors affecting the composition and stability of rhizosphere soil microaggregates are soil particle composition.(3)Salinity and alkali had a certain effect on the water holding capacity of surface soil(0-10 cm).In the study area,soil bulk density ranged from 1.36-1.43 g/cm~3,saturated water capacity ranged from 41.08 to 43.79 mm,capillary water capacity ranged from 39.95 to42.41 mm,and field water capacity ranged from 31.23 to 32.70 mm.With the increase of saline-alkali degree,soil bulk density increased obviously,saturated water capacity and capillary water capacity decreased obviously,but field water capacity did not change significantly.Soil bulk density and particle composition were the factors affecting soil water holding capacity under saline-alkali conditions.(4)Salt and alkali can affect the erodibility of non-rhizosphere soil,but have little effect on the erodibility of rhizosphere soil.In the study area,the erodibility factor K of non-rhizosphere soil was between 0.359-0.396,and increased significantly with the increase of salinity-alkali degree.The erodibility factor K of rhizosphere soil was between0.364-0.370,and had no obvious change with the increase of salinity-alkali degree.Under salt-alkali conditions,the main factors affecting the erodibility of non-rhizosphere soil and rhizosphere soil include soil particle composition,stability of microaggregates and soil organic carbon content.