Качественный состав гумуса чернозема выщелоченного в севооборотах северной лесостепи Южного Урала

Abstract

Abstract. The purpose of the research was to establish the degree of agrogenic impact on the qualitative composition of humus by monitoring the content of total carbon, humic and fulvic acid carbon in the arable soil layer of leached chernozem. A comparative assessment of the dynamics of the group composition of leached chernozem humus in the conditions of the northern forest-steppe of the Chelyabinsk region, in various crop rotations on two fertilization backgrounds P and NP was carried out. Methods. The research was carried out in a long-term field experiment from 1998 to 2021. The group composition of humus was determined in soil samples taken from each variant of the experiment every five years by the accelerated pyrophosphate method according to the scheme of I. V. Tyurin modified by V. V. Ponamareva and T. A. Plotnikova. Results. According to the results of our studies of the qualitative indicators of humus, it was found that slightly acidic soils of leached chernozem with prolonged application of mineral fertilizers in moderate doses were characterized by a dominant carbon content of humic acids (Cha), regardless of crop rotation options. It was found that the average ratio of the carbon content of humic acids to the carbon of fulvic acids against the background of P in the grain two-field crop rotation compared with the grain-pair four-field crop rotation is 25 % wider. With the permanent cultivation of spring wheat against the background of mineral nutrition NP, the ratio of carbon of humic acids to carbon of fulvic acids (Cha/Cfa) was on average 20.5 % wider during the research period, compared with the grain-steam four-field crop rotation, due to a decrease in the humification process. Strong correlations have been established between the total carbon content from the precipitation of the growing season against the background of P in the grain-pair four-field crop rotation and grain two-field. The scientific novelty lies in the study of the dynamics of changes in the orientation of the group composition of humus in different crop rotations, at different levels of fertilization and agrotechnologies of cultivation.