Soda-type composition of saline soil mainly in NaHCO_3 and Na_2CO_3, the unique engeering properties in highway construction as follows: soda-type saline soil resulted in poor drainage capacity of the road to settlement, such as road embankment collapse disease.

Salt-water regulation of soda saline soil in Songnei Plain;

Groundwater depth and mineralization have an important influence to the salinization happening and the water-salt transport of saline-sodic soil.

An experiment of leaching saline-sodic soil with brackish water was conducted for analysis of changes in physical and chemical properties of the soil,such as soil infiltration,bulk density,salt and alkali content,etc.

Variation of water and salinity in sodic saline soil during frozen-thawing season;

Water transportation between soil-groundwater in sodic saline soil system;

The regulation of dynamic change of soda-saline soil has a close relation with climate and the seasoning process of soil freezing and thawing Soil freezing and thawing will accelerate the process alkalization for the soda-saline soil The topographic changes in small area and the human activity will directly control the direction and the speed of water-soluble salts of soil.

The factors that determine conductivity of sodium saline soil are analyzed.