Soil lost through wind erosion may transport herbicides to nontarget areas. Shallow incorporation may reduce herbicide concentrations at the soil surface, thereby reducing loss on wind-erodible sediment (particles and aggregates less than 1 mm in diameter). Atrazine, alachlor, and acetochlor concentrations on and dissipation rates from surface wind-erodible sediment and larger size fractions from two soil types in undisturbed and incorporated (5 cm deep) treatments were compared. The surface 1 cm of soil was removed by vacuum 1, 7, and 21 d after herbicide treatment (DAT). This soil was dry-sieved into six size fractions (four fractions considered wind-erodible and two larger size fractions), and herbicide concentrations were determined on each size fraction. About 50% of the recovered material was classified as wind erodible sediment. Incorporation reduced herbicide concentrations on all size fractions and results were similar between soil types. Wind-erodible sediments from undisturbed and incorporated treatments contained about 65 and 8% of the applied herbicides, respectively, 1 DAT. Herbicide concentrations were similar among size fractions within a treatment 7 and 21 DAT; however, incorporation reduced soil herbicide concentrations from 50 to 80% compared to concentrations on soil from undisturbed areas. Shallow incorporation did not affect weed control ratings measured 30 DAT or herbicide dissipation. However, 50% dissipation rates (DT50) for each herbicide were about 15 d for wind-erodible sediments and ranged from 30 to 55 d for size fractions ≥1.68 mm.
Nomenclature:Acetochlor; alachlor; atrazine.