Calcium lactate as a soil amendment: Mechanistic insights into its effect on salinity, alkalinity, and aggregation in saline-alkaline soils

Abstract

Soil salinization is a problem that threatens agricultural productivity and food security. It occurs when soluble salts, sodium (Na⁺) and carbonate (CO₃^2-) ions accumulate excessively in the soil. In this study we thoroughly investigate the potential of using calcium lactate (CL) as a soil amendment to mitigate the effects caused by soil salinization. We comprehensively analyze how CL affects soil parameters such, as salinity, colloid morphology and physicochemical properties. Our hypotheses are that CL can effectively counterbalance the adverse soil pH and high salinity conditions in the soil. This happens because CL reacts with free CO₃^2- ions through an acid base neutralization reaction, which helps reduce the alkalinity of the soil. Moreover, this alteration enhances the ion exchange process between calcium (Ca²⁺) and sodium ions (Na⁺), resulting in the substitution of Ca²⁺ ions for Na⁺ ions attached to the soil particle surfaces. As a result, there is a decrease in the percentage of sodium leading to an improvement in saline soil conditions. Moreover, CL supports the formation of more stable soil aggregates, by bridging and hydrogen bonding processes thereby enhancing soil structure. Furthermore, it promotes the creation of organic mineral composites. Increases storage of carbon in the soil ultimately improving its fertility. When we compare CL to inorganic calcium salts such as CaCl₂ and gypsum it becomes apparent that CL is more environmentally friendly, safe and effective, as a soil amendment. Its main purpose is to mitigate soil salinity and improve soil quality.