Changes in Agrochemical Properties of Fallow Sod-Podzolic Soils in the Course of Their Transformation into Arable Lands

Abstract

This paper addresses the effects of the initial soil cultivation degree on the development of modern soil-formation processes affecting the agrochemical parameters of agro-sod-podzolic loamy soils. The effects were monitored in the course of a 4-year overgrowing period and subsequent land development resulting in the transformation of fallow lands into arable lands. The subject of this study was the plowing layer of agro-sod-podzolic loamy soils with various initial fertility levels affected by various uses. The field studies were carried out in the framework of a multiyear field experiment: in the course of three seven-field fallow–grain–grass rotation cycles, soils featuring three cultivation levels (medium, elevated, and high) have been formed. It is shown that even a short (4 years) overgrowing period causes a differentiation of the plowing layer into two subhorizons. The sod soil formation process caused by the decomposition of grassy weeds develops in the upper part of the plowing layer (0–10 cm); as a result, the organic matter content and the sum of exchangeable bases increase in this subhorizon. The zonal podzolic process affects the lower part of the plowing layer (10–20 cm); as a result, the humus content decreases, while the soil acidity increases. The elevated and high initial cultivation levels accelerate the differentiation of the postagrogenic horizon into sublayers. The plowing of the postagrogenic horizon eliminates the emerging differentiation in the very first year of the fallow land development. The plowed postagrogenic horizon differs from the plowing layer of similar agro-sod-podzolic loamy soils that were not withdrawn from active agricultural use: it features a higher acidity level and a slightly elevated organic matter content (by 0.060.10 abs. % or 3.3–4.8 rel. %). The cultivation level of the plowed horizon formed in the past years is preserved even in the fifth year of observation.