Changes in soil properties of differently aged abandoned lands and agrotechnical methods for the land development
Authors:   Federal Research Center “Krasnoyarsk Scientific Center of the Siberian Branch of the RAS”, Trubnikov Yu.N. , Shpedt A.A. ,   Federal Research Center “Krasnoyarsk Scientific Center of the Siberian Branch of the RAS”
Published: November 2024

The purpose of the study. Assessment of changes in the agrochemical status of soils of abandoned lands at different stages of spontaneous revegetation in the south-east of West Siberia and the development of technologies for such lands development. Location and time of the study. The research was carried out in 2014–2022 in the subtaiga and forest-steppe zones of the Krasnoyarsk Territory, confined to the Achinsk-Bogotolsky (Tyukhtetsky district, Zarechenskoye experimental field, sod-podzolic and gray forest soils) and Nazarovsky (Sharypovsky district, gray forest soils) natural areas. Methods. The age of the abandoned lands was modeled by sequentially removing arable land from the agricultural use. In studies on the humus transformation in the abandoned lands a comparative analysis of soil analogues of the abandoned and arable areas was used at the following study sites: 1) long-term arable land; 2) land abandoned for 8 and 10 years. Field experiment was carried at Zarechensky Experimental Station on abandoned lands aged 3 and 10 years during the first four years after the land was put once again in the agricultural use, cropped for wheat, oats or rye. Humus, mobile soil P and K, pH and the sum of exchangeable bases were measured in soil samples collected from the ploughed layer. The primary soil tillage consisted of ploughing in spring, followed by removing woody plants and two cultivations prior to sowing rye. Prior to sowing spring wheat and oats the soil was ploughed, cultivated an harrowed; herbicides were not used. Results. The content of humus in the sod-podzolic soil of the abandoned land increased 1,6 times over 10 years, and mobile humus substances increased 2,2 times compared with the arable soil. The newly formed humic substances were mainly of the fulvate-humate type. In the gray forest soil in the forest-steppe, the humus content in the 8-year-old abandoned land 1,2 times mainly due to humic acids. The greatest increase in humic substances was observed in the sod-podzolic soils of the abandoned lands in the subtaiga zone, followed in the descending order by the gray forest soil of the subtaiga and the gray forest soil of the forest steppe. In sod-podzolic soils the content of humus, available forms of phosphorus and potassium, as well as soil acidic/alkaline properties did not change significantly over 3 and 10 years of land abandonement. In the lands abandoned for long terms, i.e. for 15 and 25 years, the humus content increased by 33 and 55%, whereas K2O increased by 57 and 70%, the amount of exchange bases by 28 and 54%, respectively. The soil acidity and the mobile phosphorus content did not change. At the 10-year-old abandoned site the proportion of agronomically valuable fractions of soil aggregates increased by 10–15%. Compared with the arable soil, the amount of easily decomposable organic matter in soils of abandoned lands increased by 59%, or 2,5 times. Phosphorus-potassium fertilizers applied on 3- and 10-years-old abandoned lands increased the winter rye yield by 23% jn average. Spring nitrogen fertilization increased the yield by 20% and 17% more according to the longevity of abandonement. Wheat and oats yields were almost similar on abandoned lands of different ages in all variants of the experiment. Spring crops response to the application of nitrogen fertilizers was stronger. Conclusion. Abandonment of lands occupied with sod-podzolic soils in the subtaiga zone and gray forest soils in the forest-steppe resulted in a positive humus budget, which depends on the soils genesis. The largest annual increase in humic substances content was observed in sod-podzolic soils, followed in decreasing order by the gray forest soils of the subtaiga and forest steppe. In the mid-term (10–15 years) and long-term (more than 15 years) abandoned lands the soil agrophysical and agrochemical properties were improving. An area abandoned for 3–10 years can be prepared for sowing winter rye in one field season. The application of mineral fertilizers on the abandoned lands once again ploughed for agricultural use can increases the grain yields by an average of 70–100%, nitrogen fertilizers being of crucial importance. The best option for the conservation of abandoned lands occupied by acidic soils (especially in locations remote from settlements) is to stablish meadows of perennial grasses and herbs. Such lands will serve as a reliable source of feed, a place for the livestock grazing and a promising object for biological agriculture.