Vegetable residues stocks and transformation in the Krasnoyarsk region forest-steppe zone agrochernozems

In the works of Valentina Vladimirovna Chuprova, it was shown that the main source of organic matter replenishment in agrosoils of the Krasnoyarsk Region is plant residues of field crops, which enter the soil not only after harvesting, but also during the entire growing season. The studies were carried out in 2006–2020 on the territory of the Krasnoyarsk and Kansk forest-steppe, where the soil cover structure was dominated by clay-illuvial and cryogenic-micellar agrochechnozems. Agroecosystems with different anthropogenic load were selected as objects. Studies have established that the average stocks of plant residues (roots, above-ground and underground mortmass) in agricultural ecosystems decrease in the following order: natural meadows and sown hayfields (28.5 t/ha), perennial grasses (21.0 t/ha), row crops (16.0 t/ha), cabbage oilseeds (9.3 t/ha), grass mixtures (9.0 t/ha), annual grasses (6.8 t/ha), cereals and legumes (2.1–6.5 t/ha). In the studied agroecosystems, a positive balance of plant residues in the soil is maintained, with the exception of row crops (potatoes) and clean fallow. The kinetic potential of decomposition of plant residues has a close negative relationship with the ratio of carbon to nitrogen (C/N) in them and is approximated by a polynomial of the second degree, the correlation coefficient was – 89 %. It has been shown that the narrowest C / N ratio is characteristic of the phytomass of soybeans (18), the widest is for wheat straw (72) and rapeseed horses (more than 100). The highest decomposition potential is characteristic of potato tops and soybean roots (k = 0.91–0.96). Wheat straw decomposes extremely slowly, has the lowest decomposition potential (k = 0.06).