Carbon and Nitrogen Allocation and Input in Soil with Grain Crops Post-Harvest Residues: East-European Plain Case Study

In agricultural sector, there is a need to develop a methodology to indirectly determine the mass of post-harvest residues and the amount of carbon and nitrogen input and removed from agroecosystems. However, information on carbon and nitrogen content in crops cultivated in the eastern part of Europe is not sufficiently presented in scientific analytical reviews. The purpose of the study was to assess the carbon and nitrogen input in arable soils and removal from agroecosystems in relation to their allocation in phytomass fractions of crops cultivated in the East European Plain. The objects were winter wheat, spring wheat, winter rye, barley, oats, and soybean. The samples were taken in 2019–2023 in operating farms; separation into fractions was carried out and determination of the elements content was performed by the dry combustion method. The carbon content in the crops is higher than the world average, while the nitrogen content corresponds to it. The constructed equations show that for each ton of grain the mass of roots is 34–87 kg, and stubble is 62–139 kg. With cereals post-harvest residues, it remains 494–1111 kg C ha⁻¹ and 9.3–17.5 kg N ha⁻¹. Soybean additionally replenishes N-deficiency in soil by 15.3 kg N ha⁻¹ with residues and 118.5 kg N ha⁻¹ with leaves. The total removal mass of elements is 2.5–5.5 times more. This research allows to indirectly quantify with the new scheme created for a wide geographic area the removal of carbon and nitrogen by crops and their input into the arable soils with post-harvest residues according to yields known.