Glyphosate Effects on Some Characteristics of Biological Activity and Phytotoxicity of Soddy-Podzolic Soil in a Short-Term Model Experiment

摘要

-A model laboratory experiment on arable soil with low organic content and low biological activity showed short-term changes in the intensity of the main microbiological processes of the nitrogen transformation in soil after the application of glyphosate. The soil incubation with glyphosate at the maximum recommended dose of 8 L/ha for 22 days resulted in an increase in nitrogen-fixing and denitrifying activities by 30-80 and 300%, respectively, and in a decrease in nitrification by 20-40%. These effects were of a short-term nature and did not reflect the entire complex of ongoing microbiological processes. Glyphosate had no effect on the CO2 emission, an integral indicator of biological activity. At the end of incubation period, the soil with glyphosate was characterized by an increase in the number of bacteria by 40% and a decrease in the number of micromycetes by 70%. In general, under the selected conditions, the application of glyphosate led to a well-pronounced deterioration in the biological activity of the soil. The multisubstrate test showed that the application of glyphosate leads to an increase in the value of the coefficient of rank distribution of substrate utilization spectra (d) accompanied by a decrease in the specific metabolic activity (W) and the integral vitality index (G). It was shown for the first time that application of the glyphosate for the soil with a low biological activity and phosphorus availability, and the herbicide degradation with a break in the C-P bond excluding the formation of toxic metabolites have a pronounced negative effect on soil microorganisms, which leads to inhibition of wheat plant growth.