4-Amino-6-tert-butyl-3-methylsulfonyl-1,2,4-triazin-5-one (metribuzin) herbicide was used as water-dispersible granules and as a suspension conc. to study the degrdn. rate and mobility into the soil in aq. solns. under lab. conditions. The suspension conc. was more stable than the dispersible granules but was decomd. faster and was less mobile in the soil.