MICROBIAL TRANSFORMATION OF CARBON COMPOUNDS IN CHERNOZEM TYPICAL AT THE DIFFERENT AGRICULTURAL USE
Borko Yu1 Honchar A.2
1NSC «Institute of Agriculture NAAS»
2National University of Life and Environmental Science of Ukraine
Microbial transformation of organic compounds is important in soil formation processes, mineralization, and the carbon cycle. Under conditions of increased anthropogenic pressure on the soil environment, there are changes in the microbiological processes of carbon compounds transformation, which are expressed in quantitative and qualitative redistributions of the structure of soil microbial complex. Therefore, given the urgency of the problem, the study aimed to identify and compare the number of microorganisms that transform the main carbon compounds in typical chernozem. The research was carried out in the main phases of sugar beet ontogenesis in the conditions of a stationary field experiment of the NULES of Ukraine in the Forest-Steppe zone in grain-beet crop rotation. The scheme of the experiment provides the study of 3 agrarian systems (intensive – control, ecological, and biological). The number of microorganisms involved in the basic carbon compounds cycle was determined by the inoculation method of the soil suspensions on agar nutrient media with the addition of appropriate carbon sources. The amount of microorganisms during the ontogenesis of sugar beet actively involved in the transformation of cellulose is varied in the range of 3.58- 4.25 million CFU/1 g a.d.s.(absolutely dry soil), hemicellulose – 4.34-5.22 , pectin – 2.97-6.41, starch – 2.80-7.65, chitin – 1.31-3.25, lipids – 0.66-1.11, and humic substances – 2.30-3.78 million CFU/per 1 g a.d.s. The processes of transformation of soil organic matter have intensified with the growth and development of culture. It was accompanied by an increase in the amount of carbon-transforming microbiota by an average of 17.4-26.8%.
The number of microorganisms that transform carbon compounds during the sugar beet ontogenesis was lower by 12.4-23.8% under the intensive agrarian system, in comparison with ecological and biological. This is due to the imbalance of plant-microbial systems and trophic relationships as a result of the intensive use of mineral fertilizers and chemical plant protection products. The application of the biological agrarian system, due to the systematic application of only organic fertilizers, led to the activation of microorganisms that convert carbon compounds, which was accompanied by an increase in their amount. Thus, the amount of microorganisms that transform cellulose increased by 4.8–11.3%, chitin – 52.7- 96.4%, lipids – by 11.2-44.6% (during the plant culture ontogenesis), hemicellulose – by 16.2%, and humic substances – by 3.1% (full maturity phase), pectin – by 45.8-62.5% (the phase of germination and leaves closing in-row spacing). The ecological agrarian system, in comparison with the intensive one, due to the priority use of organic fertilizers and the introduction of a half dose of NPK in the soil, are helped to create conditions for the increasing of the number of microorganisms, that convert starch by – 2.2-56.0% (during ontogenesis), hemicellulose and humus substances – by 7.1-11.9% and 10.0-14.9% (phase of germination and leaves closing in-row spacing), pectin – by 59.4% (full maturity phase).
Thus, microbiocenoses with different numbers of microorganisms, which determine the processes and intensity of conversion of main carbon compounds, are formed in chernozem typical at the different agricultural use. The use of biological and ecological agrarian systems, in contrast to intensive, helps to optimize the microbial processes of transformation of carbon compounds, which is associated with increasing the amount of microorganisms that transform organic compounds.