Content of humus and labile organic matter in leached chernozem of the Plavsky District of the Tula Region under different land use patterns

The state program for the effective involvement of agricultural lands in the turnover and development of the reclamation complex of the Russian Federation has contributed to the active return of fallow lands to arable land, which in turn opens up new opportunities for studying changes in soil properties in such conditions. The article examines the issue of changes in the content of humus and labile organic matter of leached chernozem (Luvic Chernic Phaeozems) of the forest-steppe zone in the conditions of the Tula Region upon return to arable land from the fallow state. Four plots with different land use patterns were selected – arable land with spring crops, arable land with perennial grasses, fallow land put into turnover and virgin land for comparison. The studies were conducted in the period from 2022 to 2024. On the plot with permanent arable land use the average humus content in the arable layer was the lowest and most stable for three years – 6.06%. The average humus content in the soil of the virgin land and the land after plowing of perennial grasses was approximately the same and exceeded the humus content in the permanent arable land by 0.6%, the highest humus content (7.17%) was found in the soil of the plowed fallow land. The content of labile organic matter (LOM) in the arable soil layer under permanent arable land stabilized at the lowest level of 0.38% for the studied plots. The highest significant LOM content (p = 0.05) was observed in the soil horizon after plowing perennial grasses, less pronounced but also reliable increase of LOM content was observed in the soil horizon of the plowed fallow land. In these variants, in the third year after plowing, there was a noticeable decrease in the LOM content, apparently due to mineralization.