Potassium regime in postagrogenic soils that came out of cultivation at different time periods and are currently at different vegetation cover succession stages

Abstract

We present the results of a study of the potassium regime of postagrogenic soils at different stages of vegetation recovery carried out in the Leningrad region, Russia. The objects of the study were sites with meadow-shrub vegetation and young deciduous stands with regeneration of pine and spruce on postagrogenic soils formed on two-member sediments. For agrochemical analysis, soil samples were taken from an arable (0-20 cm) and underlying (20-40 cm) horizons. The content of available forms of mobile potassium correlated more closely with the soil pH at the beginning of the growing season than at the end of it. With a decrease in elevation, both the content of mobile forms of potassium and soil acidity increased, which was associated both with the migration of potassium forms along the soil profile and with the granulometric composition of soils. Potassium in the sandy loam horizon of the soil was the most mobile, in contrast to that in the light loamy former arable horizon. With age, under vegetation developing on postagrogenic soils on two-member sediments, an accumulation of both water-soluble and mobile forms of potassium in the former arable horizon can be observed, which indicates restoration of soil fertility.