Changes in Soil Adsorption Capacity under the Impact of Degradation Processes Caused by Cultivation of Agricultural Crops

The purpose of this study was to examine the adsorption capacity of degraded soils on agricultural lands (through the example of agricultural farms in the southern part of the Shakhtersk raion, Donetsk People’s Republic). The following soil parameters were analyzed: total exchangeable bases, exchangeable calcium content, and exchangeable magnesium content. To examine the soil cover of agricultural lands, model sites featuring various degradation degrees were selected taking into account the following factors: prevalence of the disturbance type within the study area, anthropogenic transformation degree, and type of cultivated crop. Soil sampling was performed in September 2023. The most significant decrease in total exchangeable bases was recorded on sites left fallow after the following preceding crops: sunflower, corn, and wheat. Compared to the control, total exchangeable bases values on such sites were lower by 56–85%. The exchangeable calcium content in soils of the studied agrocoenoses varied from 5.5 to 38.08 mmol-equiv/(100 g) soil depending on the site position in the landscape, crop rotation link, and type of cultivated crop. The lack of a proper soil maintenance system on the studied sites affects the exchangeable calcium content that has decreased on average by 42.7–84.8%. The proportion of magnesium in the total exchangeable bases ranged from 14.3 to 20.6%. The most significant decrease in the exchangeable calcium and magnesium content compared to the control was recorded on sites used for sunflower cultivation and on sites left fallow, where the cumulative effect of several unfavorable factors (sloping surface and preceding crops with higher levels of removal of mineral nutrition elements) affects these parameters.