Half life, herbicide degradation rate, Residue of herbicides

Persistence of pendimethalin and oxyfluorfen in an alfisol and vertisol was studied at three moisture levels (at saturation, Field Capacity and 50 % Field Capacity) and at two temperature levels (10 2 C and 27+ 20C) for 137 days in the laboratory. Degradation of pendimethalin and oxyfluorfen was more rapid at high temperature and moisture levels. The disappearance curve / semi logarithmic plot followed first order kinetics with two distinct pathways, an initial faster rate followed by a slower and more gradual disappearance. Half life values for pendimethalin varied from 35.45 to 108.28 in alfisol and from 28.28 to 91.84 in vertisol ; for oxyfluorfen half life values varied from 97.60 to 192.50 in Alfisols and 90.05 to 147.44 in vertisols.