Evaluating the effect of monocrotophos and glyphosate on microbial population and certain important exoenzyme activities in soil

ABSTRACT

Aim: The study aimed to evaluate the effects of various concentrations of organophosphate agrochemicals, namely monocrotophos and glyphosate on soil chemical parameters, microbial population and activities of certain vital exoenzymes e.g. invertase, amylase, cellulase, dehydrogenase and protease at 7 days interval over an incubation period of 84 days. Methodology: Three concentrations of monocrotophos (1.0 g kg-1 soil-low T1, 2.0 g kg-1 soil-medium T2, 3.0 g kg-1 soil-high T3) and glyphosate (0.1 g kg-1 soil-low T1, 0.15 g kg-1 soil-medium T2, 0.2 g kg-1 soil-high T3) were applied to soil. Soil pH, electrical conductivity, organic carbon (OC), available nitrogen, phosphorous and potassium (NPK) were assessed. Bacterial and fungal population along with activities of exoenzymes were also studied. Data were analysed using two way ANOVA and Duncan's multiple range test (DMRT). Results: Significant variations (p<0.05) of chemical parameters, except P and K, in treated soil between concentrations and time over the incubation period were observed. Microbial population and exoenzymes showed significant variations (p<0.05) in response to agrochemical treatments. Invariably, lower microbial load and enzyme activities were noticed in treated soil relative to control. Interpretation: The study indicated that monocrotophos and glyphosate at recommended and elevated concentrations in soil could adversely impact microbial growth. Inhibited microbial population culminated in lower exoenzyme activity