Effect of Pesticide and Humic Preparation on the Soil Structure during Pea and Chickpea Cultivation

The article presents the results of a 3-year experiment to study the soil structure with the combined use of insecticides and a humic preparation. Crops were peas (Pisum sativum) and chickpeas (Cicer arietinum). The experiment was carried out in 2019–2021 at the experimental fields of the Federal Rostov Agrarian Scientific Center, located in the Rostov region in the south of the European part of Russia (47°21′ N, 39°52′ E). Soil was Calcic Chernozem Loamic. The studies were carried out both without fertilization and with the use of mineral fertilizers (N40P40K40). Sowings of leguminous crops were treated with a mixture of insecticides and a humic preparation in the phase of bean formation. The humic preparation BIO-Don10 was obtained according to the authors’ technology by alkaline extraction from vermicompost—a product of manure processing by compost worms of the Eisenia foetida species. The preparation contains salts of humic acids and fulvic acids in the amount of 1.9 g/L; the concentration in the mixture with the insecticide was 0.002%. An increase in the structure and water resistance coefficients was observed. A decrease in the block fraction and an increase in the total number of agronomically valuable aggregates were substantiated. It was found that in the cultivation of legumes, the application of mineral fertilizers had a negative effect on the structure of the soil, while, when using pesticides, the structure was preserved better by the end of the growing season. The revealed patterns can be associated with the activity of microorganisms participating in the hydrolysis of organic compounds that stabilize soil aggregates.