Chernozem properties and agricultural status under different land use in the forest-steppe of West Siberia

Abstract

The aim of the study was to assess changes in soil properties and agrochemical status under different land use (undisturbed, abandoned and agricultural) in the forest-steppe of West Siberia. Location and time of the study. Soil samples (27 in total) was performed in tge Iskitim district (Novosibisrk region, Russia) in summer 2020 from the soil pits along the entire profiles rom soil genetic horizons at three sites: (US) undisturbed meadow steppe with legumes, herbs and grasses (54,668˚ NL, 83,125˚ EL); (PS) agricultural site with ploughed soil, at the time of sampling under barley, oats and vetch mixture(54,668˚ NL, 83,125˚ EL); (AS) dry stepped meadow of grasses and herbs that had been abandoned for 27 years prior to sampling (54,666˚ NL, 83,098˚ EL). Site US soil was classified as clay illuvial shallow chernozem, site PS soil was classified as dark clay illuvial shallow agrozem, whereas AS soil was identified as clay illuvial postagrogenic shallow agrochernozem (according to the Russian classification). According to the IUSS Working Group WRB classification, US and AS soils were Luvic Greyzemic Chernozem (Siltic), whereas PS had Luvic Greyzemic Chernozem (Siltic, Aric). Methods. Soils were analyzed for organic ans carbonate carbon content, total and nitrite nitrogen, mobile phosphorus content, exchangeable calcium, as well as exchangeable and unexchangeable potassium and magnesium. Soil pH was measured potentiometrically. Soil granulometry was estimated by pipette technique after dispersion in sodium pyrophosphate. Main results. The presence of sod (horizon AUrz) and powdery grains of biogenic structure of the humus horizon are the main features of the undisturbed chernozem. The grainy soil structure was destroyed by ploughing, and, consequently, could not be found in the agrozem. Restoration of these features is important indicator of the postagrogenic transformation. As compared with the US soil, the AS one showed lower humus and total nitrogen content and stocks, especially in the ploughed horizon, but the difference was not statistically significant. These soil properties were found to be increased after 27 years of postagrogenic spontaneous restoration at the AS site. According to the studied soil properties, the agrochemical status of the studied undisturbed, abandoned and ploughed soil can be described as favorable for plant growth and crop production. Conclusions. The studied chernozems of the forest-steppe in West Siberia (undisturbed, ploughed and abandoned sites showed differences in their profile and surface horizon structure, carbonate layer location, the contents of mobile phosphorus, exchangeable magnesium. The topsoil (0–5 cm) at the undisturbed and abandoned sites accumulates biogenic elements (organic carbon, total and nitrate nitrogen, easily mobile phosphorus and exchangeable potassium. The absence of the difference in soil properties between the three studied site proves chernozem to be rather resistant to agrogenic influence. The site that had been abandoned for almost three decades, can be once again put int agricultural use. It should be emphasized that in Siberia the crop yields, especially grains, on chernozems are produced mainly by soil resources of mobile microelements without compensation their removal by fertilization. The agrogenic transformation rate and degree of Siberian chernozems are higher as compared with the European part of Russia. Therefore, we recommend monitoring agrochernoems fertility, especially after abandoned land are put once again in the agricultural use.