Effect of application of plant protection agents and a biologically active preparation on agrophysical properties of ordinary carbonate chernozem in stationary experiment
Purpose: to study the effect of a humic preparation and plant protection agents on the content of agronomically valuable aggregate fractions, their water stability and total carbohydrate content. Materials and methods. The experiment was carried out on ordinary carbonate chernozem at Federal Rostov Agricultural Research Centre station. Soil samples were analyzed by the method of dry and wet sieving, the assessment was carried out according to the value of structure coefficients, aggregate water stability and the API criterion, the content of total carbohydrates was determined in agronomically valuable fractions by Dubois method. Results. In terms of the structure coefficient, when compared with the control, a significant difference was noted in 2018 when a humic preparation was applied together with protective agents (A = +0.65), in 2019 in the variant with a humic preparation (A = +4.23), in 2020 the results were similar. The dynamics of water-stable aggregate content had a similar character: the treatment of crops with a humic preparation gave an increase in the number of agronomically valuable aggregates, in comparison with the control: in 2018, A = +5.81 %, in 2019 A = +21.3 %. In 2020, an increase was obtained in the variant with a humic preparation and when applied together with pesticides: +12.05 and +18.1 %, respectively. The water stable criterion (the API criterion) showed significant difference with the control in the variant of using pesticides and humate (A = +20.59 %). In the variant with pesticides, the decrease in the API criterion is insignificant. In 2020, after treatment with the preparations, the content of carbohydrates in the structural separates varied from 0.86 to 1.05 %; in comparison with the control, a significant difference was observed: respectively, A = +0.08 % and A = +0.06 % in the variant with humate and humate with pesticides. Conclusions. The humic preparation has a positive effect on the structural and aggregate composition, and the water stability of soil separates increases.