Assessment of the direction of microbiological processes in Ukrainian chernozems in pea-barley intercropping agrocenosis under the influence of biostimulants

O. Tonkha¹, R. Tomashevskii¹, B. Mazurenko¹, O. Pikovska¹, O. Litvinova¹, O. Kravchenko¹, T. Maievska², S. Azarkamand³, T. Melnychuk¹, O. Havryliuk¹ and K. Shemetun¹

¹National University of Life and Environmental Sciences of Ukraine, Heroiv Oborony Str.13, UA–03041 Kyiv, Ukraine
²Ukraine’s Fishing Industry Cluster of Innovation, 18/B, Instutytska Street, UA–01021 Kyiv, Ukraine
³UNESCO Chair in Life Cycle and Climate Change ESCI-UPF, Pg. Pujades 1, ES08003 Barcelona, Spain
*Corresponding author: o.havryliuk@nubip.edu.ua

Abstract:

Soil microorganisms are an important component of agroecosystems, and their structure, number and ratio allow us to characterize the direction of microbiological processes in the soil. The aim of this study was to determine impact of application of biostimulators on the activity of microbiological processes in typical chernozem soil in agrocoenosis of pea-barley intercrops. The effect of different biostimulators in pea-barley intercropping on the number of different groups of microorganisms on the 7^th, 60^th and 90^th day after emergence was established in field experiment on typical chernozem in Ukraine. Coefficients of mineralization-immobilization, oligotrophicity and pedotrophicity were calculated to determine the directionality of microbiological processes in the soil. The greatest impact on microbial biomass during the vegetation period was observed with the application of insect frass extract, particularly at 60 DAE, where the indicator reached 302 million CFU in the 0–20 cm soil layer. The use of vermicompost increased the number of ammonifying microorganisms to 14.3 million CFU in the 0–20 cm layer and 10.1 million CFU in the 20–40 cm layer. In contrast, the application of compost tea, humus extract, and fish hydrolysate almost halved the number of these microorganisms compared to the control on the 60th day. At 90 DAE, the highest number of ammonifying bacteria was recorded with compost tea are7.8 CFU per 1.0 g of dry soil in the 0–20 cm layer and 4.8 CFU per 1.0 g of dry soil in the 20–40 cm layer. The highest number of amylolytic microorganisms was observed with the insect extract are 12.4 million CFU per 1.0 g of soil compared to 6.6 million CFU in the control. Regarding the content of phosphate-mobilizing microorganisms on the 60th day, only the insect frass variant showed an advantage over the control in the 0–20 cm layer (16.7 million CFU), while vermicompost showed the highest number in the 20–40 cm layer (10.4 million CFU); the other biopreparations showed lower values. Thus, the use of biopreparations on pea-barley intercrops caused a significant impact on the microbiological activity of the soil and the content of labile organic substances.

Key words:

biological activity, microbiota, soil, soil organic matter