The effectiveness of the use of plant growth stimulants for growing corn on over-compacted soils

Goal. To investigate the influence of growth stimulants Vympel and Azotofit-R on the growth and development of corn plants of semi-intensive (Leleka-MV variety) and intensive (Kardynal-MV variety) types, as well as on their root system at growing on the over-compacted seed layer of soil. Methods. Laboratory — for conducting a model experiment, laboratory-analytical — for determining the parameters of the root system of plants, mathematical-statistical — for the analysis of variance of the data obtained. Results. The study was carried out under the conditions of a model laboratory experiment on typical low-humus heavy-clay on loess-like loam chornozem. General characteristics of the soil: pHsalt — 6.2; hydrolytic acidity — 1.4 mmol/100 g; total content of humus — 5.0%, mineral nitrogen — 27.9 mg/kg of soil, phosphorus, and potassium (according to Chyrikov) — 252.9 and 472.6 mg/kg of soil, respectively. It was found that the growth indicators of the root system — the length, diameter, and productivity factor of the roots — on the overcompacted soil were much lower compared to the control, for which the optimal level of density of the structure was reproduced. It was proved that inoculation of seeds with growth stimulants was an effective means of improving the development of the root system of corn under the conditions of its cultivation on the over-compacted seed layer of soil: the length of corn roots increased by 7–26% and the diameter — by 4–26% depending on the version of the experiment. Inoculation of seeds with a soil growth stimulator positively influenced the productivity of the root system of both studied types of corn. However, semi-intensive corn plants growing on compacted soils turned out to be more adaptive to adverse conditions. In conditions of an over-compacted seed layer of soil, the biological yield of an intensive-type crop was reduced by 35%, and of a semi-intensive crop by 26% compared to growing under conditions of an intensive level of soil structure density. Conclusions. The increase in the length, diameter, and productivity factor of the corn root system in the case of inoculation of seeds before sowing with the plant growth stimulator Vympel and the biostimulant Azotofit-R contributed to an increase in the total biological yield of both types of crops. The feasibility of growing semi-intensive corn varieties on overcompacted soils, which are more adapted to adverse environmental conditions, is scientifically substantiated.