Early Stages of the Evolution of Chernozems under Forest Vegetation (Belgorod Oblast)

Abstract

We studied automorphic forest-steppe Luvic and Haplic Chernozems (Siltic/Clayic, Pachic) of the southern part of the Central Russian Upland (Belgorod region), which were covered with broadleaved forest vegetation at different times (from 25 to 75 years ago). The studies were carried out on an overgrowing fallow and the adjacent maple-ash shelterbelt and on an area of growth of a natural oak forest towards the virgin meadow steppe. The line of effervescence in the soil profiles descended by 12-25 cm during 60-75 years of the growth of forest vegetation on Chernozems. The average rate of carbonate carbon leaching from a 2-m soil layer reached 5 t/ha per decade. The humus horizon thickness increased by 7-13 cm. A decrease in the organic carbon storage was observed in the soil profiles during the first 25-30 years of the development of Chernozems under forest vegetation; in the following decades, the organic carbon storage increased. The soil organic matter in the upper part of the profiles (0-40 cm) was directionally enriched with fulvic acids, while the opposite tendency of an increase in the content of humic acids was observed in the middle part of the profiles (40-80 cm). The clay mobility increased in the Chernozems under forest vegetation, which is proved by an increase in the content of silty infillings in the studied chronosequence of Chernozems under tree stands of different ages (from 25 to 60-75 years) and by the appearance of clay-humus cutans in the soils under forest vegetation. The direction and staging of changes characterize the evolutionary transformation of Chernozems over time under the impact of forest vegetation. Soil changes were caused by changes in vegetation from herbaceous (meadow-steppe) to forest and the resulting changes in the hydrothermal regimes of soil formation. The staging of soil changes could be determined by the vegetation succession changes coupled with corresponding changes in the soil regimes in microclimatic conditions.

Inversion Tillage Combined with Organic Fertilizer Application Increased Maize Yield via Improving Soil Pore Structure and Enzymatic Activity in Haplic Chernozem

“…The secretion of soil microorganisms also increased SOC and available nutrient contents, which is consistent with the findings of Chen and Yang et al [15,31]. Previous studies have also suggested that tillage practices improve soil nutrient supply capacity in Chernozem [1,2]. Soil organic matter decomposition was facilitated by the favorable conditions for microbial activity and biochemical reactions, which may have led to the accumulation of SOC and soil nutrients in the 0-15 cm layer under T15+M [18].…”

“…In agroecosystems, organic fertilizer is an essential organic carbon source, and inversion tillage has great potential to sequester carbon in arable soil. Effective tillage and fertilization measures can improve soil properties and increase crop yields [1,2]. Inversion tillage can break the plow pan, deepen the cultivated horizon, improve soil pore characteristics, and enhance soil infiltration and moisture retention capacity [3][4][5].…”