Establishment of Perennial Wheatgrasses in Relation to Atrazine Residue in the Seedbed

Abstract

Perennial wheatgrasses were seeded in fall, 1967 and 1968 on fallows created by atrazine at 1 lb./acre applied the previous fall or by mechanical means. Atrazine residue in the soil during seedling establishment (1.5 years after application) ranged from < 0.04 to 0.15, 0.09, 0.08, and 0.06 ppm, respectively, in the 0-1, 1-2, 2-3, and 3-4-inch soil samples. Residue was less than 0.04 ppm from 4 to 8 inches. Seedlings of perennial grasses were injured or killed by these residue levels. However, poor stands were obtained at only two of seven locations in 1969 with crested wheatgrass. Generally, stands of intermediate and pubescent wheatgrasses were superior to crested wheatgrass. Species response was also evaluated on fallows created by 0.5, 1.5, and 2.0 lb./acre atrazine.