Effect of different glyphosate salts on phosphodiesterase and phosphotriesterase activities in soil with reference to ecological importance of soil pollution. A laboratory experiment

The aim of this study is to determine the effect of the two glyphosate salts: isopropylamine and potassium (contained in preparations Roundup) on the activity of phosphodiesterase and phosphotriesterase in the soil. The experiment was carried out in the laboratory conditions on two soil types: loamy sand (C_org 8.70 g·kg⁻¹, pH_KCl 6.39) and sandy loam (C_org 10.90 g·kg⁻¹, pH_KCl 6.81). Two glyphosate salts (isopropylamine and potassium) in dosage of 0, 1 and 100 mg·kg⁻¹ were applicate into soils. Phosphodiesterase and phospotriesterase activities in soils were determined spectrophotometrically on days 1, 7, 14, 28, 56 and 112. The obtained results were converted with respect to the enzyme activities in the control soil (assuming it to be 100%) and given as percent of inhibition. The results were shown as environmental danger zones graphs. Obtained results showed that glyphosate salts application has primarily resulted in inhibition of phosphodiesterase activity, and stimulation of phosphotriesterase activity in soils. Soil type and kind of glyphosate salt affect the interaction of herbicide with phosphodiesterase and phosphotriesterase activities. The observed changes in the phosphodiesterase and phosphotriesterase activities caused by the addition of both glyphosate salts were located on environmental danger zones graphs in the range of negligible or acceptable values, which may indicate a low impact of herbicide on measured enzymes.