Effect of Atrazine Residue on Soybean Growth Under Three Tillage Systems and Various Herbicides

Field experiments were conducted to examine the effect of tillage on atrazine [6-chloro- N -ethyl- N ′-(1-methylethyl)-1,3,5-triazine-2,4-diamine] persistence in the soil and soybean [ Glycine max (L.) Merr.] injury. Tillage systems evaluated were no-tillage, chisel plowing, and moldboard plowing. Reduced tillage systems, such as no-tillage or chisel plowing, resulted in greater soybean injury from atrazine residue than did moldboard plowing. Regardless of atrazine residue level, metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4 H )-one] resulted in the greatest injury to soybeans. Metribuzin application in combination with atrazine residue increased soybean injury under the chisel plowed system.