Study on the Leaching Status of Magnesium Nutrients in Soil and its Influencing Factors

Mg is one of the essential medium elements for plant growth and an essential mineral nutrient in agricultural production. In this paper, we summarize the past series of plant Mg nutrition studies and Mg leaching tests in field soils to reveal the leaching status of Mg elements in soils today and their influencing factors. According to the test results of 325 609 soils in the 2016 National Soil Testing and Formulation Program, Mg-deficient soils with exchangeable Mg content (Mgex) <50 mg-kg-1 accounted for 43.8% of soils in the country; among them, soils with 25-50 mg-kg-1 accounted for 7.64%, and those with Mgex <25 mg-kg-1 accounted for 36.14%, and soils in China had a more serious deficient The salinization, acid-alkalization, high heavy metal content and intense leaching of the soil were the important influencing factors for its lack of Mg supply. Positive effect factors of soil Mg leaching include soil exchange Mg content, type of fibrous root crop, light-textured soil, desorption of soil Mg, and weathering of parent material; negative effect factors include type of taproot crop, root secretion, biomass fixation, soil pH and organic matter, colloidal adsorption, and precipitation mineralization.