Effect of quality of dispersing solutions on soil aggregates stabilities during the wet-sieving test

【Objectives】Soil aggregates are the basic units of soil structure. Sufficient chemical stability of soil aggregates is necessary for maintaining good soil moisture and fertility. Large amount of cations are brought into soil through fertilization and irrigation, which affect the aggregates stability to some extent. In this paper, the stability of aggregate in organicrich black soil was determined in the three cation solutions. 【Methods】Three kinds of cation solution, sodium chloride, chlorinated calcium chloride and aluminum chloride with four concentrations 0 mol/L (de-ionized water without salt, CK), 0.1 mol/L, 0.3 mol/L and 0.5 mol/L are set up as media, and the stability of soil aggregates (0.25 mm in size) was tested using an improved Savi Chizhov (Саввинов) method.【Results】The results show that the stabilities of soil aggregate (PAD0.25/W values) are quite different in different salt solution media. In sodium chloride solution, PAD0.25/W values are all positive, and the soil aggregate destruction rate is increased with the salt concentration, the PAD0.25/W values are 0.21%, 10.7% and 14.4% in 0.1, 0.3 and 0.5 mol/L of sodium chloride solution, respectively, showing the dispersion effect of the sodium salt to soil aggregates.In calcium chloride and aluminum chloride solutions, the PAD0.25/w values are negative, and the absolute value of PAD0.25/w is decreased with the increase of salt concentrations. Inside the aluminum chloride solutions, all the absolute PAD0.25/w values are higher than 51%.【Conclusions】Monovalent salt solution exacerbates the dispersion of 0.25-1 mm aggregates, protects the aggregates of more than 1 mm in diameter from dispersion. Divalent salt and trivalent salt show inhibition and protection to the dispersion of aggregates showing ability of strengthen soil aggregates.