Soil-ecological assessment of soils of abandoned lands of diggerent age in the southeast of West Siberia

Abstract

The aim of the study. Assessment of the current state of agrophysical properties of soils, their soil-ecological status by calculating the soil-ecological index (SEI), as well as the study of vegetation cover of different-age abandoned lands in the forest-steppe zone of West Siberia within the Novosibirsk region. Location and time of the study. Novosibirsk Region, 2017–2022. Methods. Soils of the Predsalair drained plain (right-bank part of the Novosibirsk region) were studied. Twelve soil sections were studied on leached and podzolized chernozems, as well as on dark gray forest soils. Some of the studied soils had different degrees of washout prior to abandonment. The abandoned lands were young (2–4 years), middle (5–15 years) and old (more than 15 years). The age of these lands, i.e. the duration of their spontaneous self-revegetation, was determined based on satellite imagery data, information from local authorities and the methodology developed by the Institute of Soil Science and Agrochemistry of the Siberian Branch of the Russian Academy of Sciences. The study of vegetation cover was carried out according to standard methods. Soil samples were collected as a solid column; humus content, acidity, mobile forms of phosphorus and potassium, granulometric composition were determined. Samples were also taken to determine soil density (volumetric mass). For soil-ecological assessment the methodology of soil-ecological index (SEI) calculation was used. The methodology for SEI calculating combines soil fertility, climatic and geomorphologic soil factors. The SEI was calculated according to the methodology developed at the В.V. Dokuchaev Soil Institute by I.I. Karmanov. The following soil properties were also measured: granulometric composition by the sieve-pipette method, organic carbon (humus) by potassium dichromate digestion and pH by potentiometric method. Results. The article presents the agrophysical properties of soils, their soil-ecological assessment (SEI) and describes the vegetation cover of different-aged abandoned and revegetating lands in the forest-steppe zone of West Siberia within the Novosibirsk region. The vegetation revealed a smooth change in the species composition of plants, including a decrease in the proportion of annual and biennial species. The total aboveground production increased during the first 5–7 years of revegetation, afterwards reaching a plateau depending on the type of the formed community and conditions. Low values of SEI (38–41) were obtained for young and middle-aged abandoned lands in comparison with the virgin land (63), being caused by the lower content of nutrient elements and humus. In the long-term abandoned lands soils, that were not washed away, had an average SEI value of 55, while soils of old fallow lands previously washed away had an average 45. Conclusions. Based on the soil ecological condition in the studied abandoned lands, it can be concluded that the return of young and middle-aged lands to agricultural turnover makes sense as pastures and hayfields. Their use as arable land is inexpedient, mostly because of different degrees of washout due to their location on slopes of different length and steepness, as well as insufficient restoration of their properties. The old abandoned lands (in case of the absence of soil erosion) may well be returned to agricultural use, including as arable land.