Effect of Three Tillage Systems on the Persistence of Atrazine

Field sudies on the persistence of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] showed less persistence under coulter than chisel or conventional plow tillage in the year of application. The residue on the coulter system from the previous corn (Zea maysL.) crop initially prevented as much as 30% of the atrazine from reaching the soil surface. After five annual applications, the atrazine residue was generally higher in the coulter than the chisel or conventional tillage systems, but below levels considered to be biologically active.