Soybean response to preplant application of auxin herbicides at different soil textures

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Glyphosate-resistant or tolerant broadleaves are often controlled using auxin herbicides before soybean planting. However, a safe interval is essential prior soybean planting, depending on soil properties. In the literature, there is little information about auxin herbicides on the behavior of auxin herbicide at different soil texture. Two soil residual bioassays were conducted in a greenhouse to evaluate response to soybean to preplant applications of 2,4-D and dicamba at different soil textures. Herbicides were applied 28, 21, 14, 7, 3 and 0 days before soybean planting (DBP) and the soil texture consisted 15, 35 and 60 % clay. The residual activity was determined through the injury, plant height and dry weight of soybean at 28 DBP. Soil residues from 2,4-D was less deleterious to soybean than dicamba. The herbicides injury is reduced in clayey soil. Shorter intervals of herbicide application increased the injury and reduce height and dry weight of soybean. Soil texture not influence on height and dry weight from 2,4-D. Dicamba caused high injuries in medium soil compared to clayey and sandy soil, and clayey soil revealed cause lower effect on height and dry weight of soybean. The 2,4-D application in clayey soil reduces the interval to soybean planting, but soil texture not influence on initial soybean development. The 2,4-D application in clayey soil reduces soybean injury, but soil texture not influence on initial soybean development. Up to the 28-days interval, there are no indications of soil texture effect on the herbicide dissipation security for soybean planting.