EFFECTS OF HERBICIDES ON CELLULOLYTIC ACTIVITY IN PEAT SOIL

Effects of two herbicides, viz glufosinate-ammonium and imazapyr, on cellulose decomposition were studied in laboratory experiments. The herbicides were either incorporated in soil or sprayed onto cellulosic substrate before burial. Glufosinate-ammonium or imazapyr applied directly to the substrates before burial reduced the decomposition of the substrate. When the substrate was buried in soil immediately after treatment, the decomposition rate in soil treated with either glufosinate-ammonium or imazapyr at 150 ppm decreased by 86% and 78% of the decomposition rate of the control, respectively. Cellulose decomposition was not affected significantly in soil treated with imazapyr. It was reduced by 81% of control in the presence of glufosinate-ammonium at 150 ppm. In non-preincubated soil, carboxymethyl cellulase (CMCase) activity of the substrate treated with either herbicide decreased proportionately with increasing concentrations. Only imazapyr at 20 ppm caused a slight reduction in CMCase activity when the substrate was buried in soil incubated for 4 weeks.