Field experiments were conducted during kharif seasons of 1995 and 1996 to determine the most economic and eco-friendly weed management in soybean [Glycine max (L.). Merrill]. Application of low dose (0.50 kg/ha) of metribuzin as pre-emergence appreciably lowered the weed population and weed biomass than pendimethalin (1.0 and 1.5 kg/ha) and was comparable to two hand weedings done at 20 and 40 DAS. But high dose (0.75 kg/ha) of metribuzin had a little phytotoxic effect on soybean seedlings. The former treatment fetched a maximum net monetary return (Rs. 9590/ha) and benefit: cost ratio (2.22). In sandy loam soil of Dellti, the halflife of metribuzin at 0.50 and 0.75 kg/ha application rates, ranged between 43 to 49 days, respectively. The rate of dissipation of metribuzin did not follow first order kinetics at either rate of application. The initial dissipation of metribuzin was acute and about 50% of the original amount was lost in 45 days and provided safety to the following crops as the metribuzin residues dissipated to a non-detectable level after the harvest of soybean crop.
