APPLICATION OF ZEOLITE IN IMPROVEMENT OF SALINE-ALKALI SOIL IN NORTHEAST CHINA

The salinization of black land in Northeast China, especially Songnen Plain, is accelerating, greatly challenging the food security in black land. Therefore, the improvement of saline-alkali soil becomes important. The main influencing factors include semi-arid climate, geological conditions, low-lying terrain and groundwater level. The soda saline-alkali lands are well developed in Songnen Plain, with Na⁺ as the major positive ion, CO₃^2- and HCO₃^- negative ions in soil salt, characterized by high alkalization. As both the exchanger and adsorbent of ions, zeolite can absorb Na⁺ and SO₄^2- in saline-alkali soil, reducing soil pH and alkalinity. Moreover, it can increase the capacity of soil to retain NH₄⁺, PO₄^3- and K⁺, and improve nutrient availability, which is significantly effective in soil improvement. However, due to the uncertainty of zeolite modification, dosage and aging, the future study should pay more attention to the soil improvement in saline-alkali land by zeolite according to local conditions and strengthen the research on zeolite modification and regeneration, so that zeolite can play a greater role in desalination and alkali reduction.