The study of the rate of decomposition of the biomass of agricultural crops cultivated in the Central Chernozem region showed that several years pass from the moment the residues enter the soil to their complete decomposition. The intake of post-harvest inhumified residues into the arable layer of the soil occurs annually (stubble, roots, etc.), so there is always a certain stock of plant residues from previous years, which are at different stages of decomposition. Therefore, at the time of harvesting, the soil contains plant remains of the harvested crop and the remains of crops previously cultivated in this field, i.e., the remains of previous years.