Saline-alkaline soils in China are mainly distributed in northwest, north, northeast and coastal areas, including saline soils and alkaline soils. Saline soils mainly contain a large amount of soluble salts, mainly sodium chloride and sodium sulfate, with a pH value of 8-9. Alkaline soils mainly contain carbonic acid. Sodium, sodium bicarbonate, pH 9-10, alkaline.

The main harm of saline-alkali soil is that the soil salt content is too high, the harmful ion concentration is too large, the soil acidity and alkalinity is too strong, the soil particles are highly dispersed, the soil structure is poor, and the growth is inhibited. Long-term application of large amounts of corrosive acids can gradually Change the physical and chemical properties of saline-alkali soil.

1. Formation of rent soil aggregates.

Soil aggregate is the basic unit of soil structure. It is a larger soil particle formed by a single soil particle bonded by organic and inorganic colloids such as soil humus and clay. Fragmentation, loose and porous, can adjust soil water, fertilizer, gas and heat conditions. Coal humic acid is an organic colloid, long-term application can promote the formation of soil aggregates, improve soil structure, make soil aeration, good water permeability, in order to speed up The leaching of soluble salts and root growth and development created favorable conditions.

2. Reduce the salt content of the topsoil.

Concentrated application of corrosive acids, transporting the soil in the plough layer, destroying the conditions for the rise of salt along the soil capillary pores with water, reducing the accumulation of salt in the topsoil, reducing the salt content in the topsoil, playing the role of separating salt, and reducing the harm of salinity to crop seedlings, Improve the emergence rate and reduce weak and dead seedlings.

3. Improve soil replacement capacity.

Humic acid has a high cation exchange capacity, which is more than 10 times higher than that of ordinary soil. Soil application, the soil's ability to adsorb harmful ions is significantly improved.

4. Reduce the pH of saline-alkali soil.

The application of humus can improve the physical and chemical properties of the soil, inhibit the rise of salinity, neutralize the alkalinity of the soil, reduce the harm of salinity and alkali through the adsorption of cations, create good soil conditions for the growth of crop seedlings, and improve the low-yield saline-alkali soil.