BIOLOGICAL SOIL ACTIVITY IN SOYBEAN AGROCENOSIS UNDER SEPARATE AND INTEGRATED USE OF HERBICIDES AND BIOLOGICAL AGENTS

Abstract

Soil microbiocenosis takes part in the formation of important soil properties that determine its taxonomic characteristics: focus, intensity and type of soil formation processes, promotes biodynamic balance of the synthesis and destruction processes of organic matter, evolves growth activating agents and ensures the availability of nutrients for plants.

The aim of this research was to investigate the effect of different herbicide norms and methods of application of plant growth regulators applied at the time of seed treatment by microbiological agent and separately on the development and operation of major groups of soil microbiota and their enzymatic activity at agrocenoses of soybeans. Experiments for the study of Fabian herbicide effect, plant growth regulator Rehoplant and microbiological agent Ryzobofit in soybean seeds of Romantica variety on the development and operation of major groups of microorganisms and determination of their impact on soil enzymatic activity were performed during the years 2013‒2015 in the field and in the laboratory of Uman National University of Horticulture.

As a result, the research found that the number of bacteria, micromycetes and actinomycetes in the rhizosphere of soybean depended on the type and method of applying agents and their combination. The highest number of them was formed in versions with using of herbicide Fabian 90‒110 g/ha in mixtures with plant growth regulator Rehoplant 50 ml/ha, applied at the time of preplant seeds treatment by Ryzobofit 100ml/t along with Rehoplant 250ml/t.

Also, it was found that the activity of soil enzymes in the experiment depended on the norm of application of the herbicide and combining of their use with biological agents. The increase of enzyme activity in version Fabian 90 g/ha, applied with plant growth regulator Rehoplant 50 ml/ha at the time of preplant seeds treatment by Ryzobofit 100ml/t + Rehoplant 250ml/t mixture is obviously a consequence of increasing transformation processes in soil which heighten under the integrated effect of chemical and biological agents.

The obtained experimental data leads to the conclusion that the number of soil microbiota and soil enzyme activity in seeds of soybean  depends on the effect of different norms of herbicide and combining of their use with biological agents: the number of soil microbiota soybean seeds is reduced with the increase of norms of Fabian herbicide; the integrated effect on biological soil activity was effective under preplant seeds treatment by a mixture of Ryzobofit (100 ml/t) and Rehoplant (250 ml/t) with after-germination of minimum norms of herbicide Fabian (90 g/ha) in combination with plant growth regulator Rehoplant (50 ml/ha) which resulted in the increase of the total number of bacteria by 59%, micromycetes‒ 55%, actinomycetes‒ 35%, with a simultaneous increase in the enzymatic soil activity by 28%; 50% and 62% respectively for invertase, catalase and protease.