Dissipation of nicosulfuron and rimsulfuron in surface soil.

Field and soil fortification studies were conducted to evaluate the half-lives (DT(50)) of nicosulfuron and rimsulfuron in a Sequatchie silt loam surface soil. The dissipation of each herbicide was also evaluated with the two compounds applied simultaneously, which is a typical application method used in corn production. Field studies in two years indicated that both herbicides alone and in mixture disappeared quickly, with all DT(50) < 6 days. Environmental conditions including warm, moist soil, and a soil pH of 5.7 encouraged rapid herbicide dissipation. Rapid degradation was observed under laboratory conditions using this same soil, with all DT(50) < 3 days. This research indicated minimal risk of carry-over to subsequent rotational crops and minimal residual weed control from these herbicides when applied to a silt loam soil under ambient climatic conditions in Tennessee.