Patterns of differentiation of the old arable horizon of fallow soils according to the content of mobile forms of manganese and copper

Abstract

The differentiation of the old arable horizon (Ap old) by the content of mobile manganese (Mn) and copper (Cu) under fallow vegetation aged 15-20 years was studied. The accumulation of mobile Mn in the upper layer (0-10 cm), Cu in the 5-15 cm layer was observed. Linear modeling of the dependence of the content of Mn and Cu on alkali-soluble organic matter (OMP) and pH showed the influence of only one significant predictor on each element. The content of Mn has a significant strong (R2 adj.=0.72) influence of OMP. The pH has a statistically significant, but weak (R2 adj.= 0.19) effect on the Cu content. The difference in the patterns of differentiation is associated with the accumulation of mobile Mn by newly formed organic matter (OM) in fallows and the migration of mobile Cu with soluble fractions of OM in acidic soils. The study of changes in the mobility of heavy metals (HMs) in fallows is necessary to reduce environmental risks when changing land use, as well as to provide a realistic prediction of atmospheric carbon sequestration in fallow soils, taking into account changes in the level of toxicity of HMs. The relevance of these studies is associated with the fact that the removal of lands with heavy HM contamination from arable circulation in fallows is practiced more and more often.