Soil Persistence of Trifluralin, Benefin, and Nitralin

Abstract

Trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline], and benefin (N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine) were applied at two rates for five consecutive years (1966 through 1970) as soil-incorporated treatments to cotton (Gossypium hirsutumL. ‘Acala SJ-1’) before the preplanting irrigation. Repeated applications did not significantly affect stand or yield of cotton. Soil samples taken to depth of 120 cm showed that herbicide residues were confined to the tilled zone of soil (upper 30 cm), and about 80% of the residue was in the upper 15 cm of soil. The amount of herbicide residue found annually in the upper 15 cm of soil varied with herbicide and with season. Residues 15 months after final application had been reduced markedly, but were still sufficient to injure sensitive crops. Residues at 30 months had been reduced to innocuous amounts.