Inorganic improver and straw returning promote corn growth and improve the quality of saline soils

Soil salinisation is a major constraint on food security and agricultural development, and remains a critical concern in the agricultural sector. In this study, we examined the effects of three straw return methods – straw mulching, straw burial, and a combination of straw mulching and burial – along with inorganic amendments (CaSiO3 and MgSO4) on maize growth, soil organic matter, bulk density, salinity, and the contents of individual salt base ions. A 120-day planting experiment was conducted using soil columns and included maize cultivation under irrigation and drenching conditions. The combined treatments (straw return with Ca-Mg application) were more effective in reducing salinity and improving soil properties than straw return alone. Na+, K+, Cl–, and HCO3 contents, as well as soil bulk density, decreased by 45.99–48.43, 28.07–28.36, 20.91–24.17, 18.93–21.03, and 7.64–8.40%, respectively. Regarding crop growth promotion, compared with the single treatment, the combined application of straw return with Ca-Mg (PI, SPI) resulted in a 6.46–8.30% increase in superoxide dismutase activity, an 8.66–10.83% reduction in malondialdehyde content, a 12.71–22.70% increase in total root length, a 13.41–24.14% increase in root surface area, and a 12.46–19.02% increase in root volume. Taken together, integrating straw return with a calcium-magnesium mixture represents a promising strategy for improving the quality of coastal saline soils.