The effect of phosphates on the transformation of iron, aluminum, and phosphorus derivatives of humus in gray forest soil

摘要

A close correlation between the chemical properties of phosphorus derivatives in the soil and the evolution of humus transformation and its iron and aluminum compounds was revealed. Qualitative transformation of humic acids occurred under the effect of inorganic orthophosphates, which was manifested by a decrease in their saturation in phosphorus and an enhancement of electron-donating properties (Lewis basicity). This affected the spectral properties and reactivity of organic compounds in the soil, particularly their hydrolyzability in the alkaline, acid, and neutral media. Chemical properties of organometallic complexes, mainly of iron complexes, determined the soil capacity for restoring the initial saturation of humic acids in phosphorus. The irreversible transformation of humic acid was associated with the formation of nonelectrolyte complexes inactive in polar media. The evolution of chemical reactions toward the formation of nonionic chelate compounds in a cultivated soil was more pronounced than in a virgin soil.