Evaluación del efecto de la volatilización de diferentes formulaciones de 2,4-D y Dicamba en el cultivo de soja

The expansión of the area of soybean cultivation and the increased weed of difficult control led to increased use of herbicides, and adaptation of new technologies such as Enlist (whit possibility of application in post emergency of 2,4-D), glyphosate and gluphosinate of ammonium. The coexistence of crops with tolerance and susceptible to herbicide 2,4-D, require a correct use, for safe and efficient use, reducing the risks associated with the application of the herbicide, especially volatilization. Being that it is one of the loss processes that a herbicide can have, and that has a high impact on sensitive crops as well as on the environment and human health. In this context, the aim of this paper was to provide information on same of the main factors that favor the volatilization of herbicides, evaluating the effects of formulations of 2,4-D, and also the herbicide Dicamba, it is relationship to soil moisture, temperature, wind, exposure period and distance from the application area. For this purpose, susceptible soya plants were used as a bioindicator species using a scale of 0 to 10 assess volatilization damage. Three experiments were performed using random complete block design. Two of the experiments were performed under the growth chamber evaluating in the first of them the damage effect of Dicamba and three formulations of 2,4-D, a 15ºC, 25ºC, and 35ºC on wet and dry soil. The second, using the same herbicides as the experiment one, the wet and dry soil with five exposure periods of treatments. And finally, the third experiment went to field, in paddock 6A, of the Mario A. Cassinoni experimental station of the Faculty of Agronomy, where the effects of 2,4-D dimethylamine and 2,4-D choline applied in an area of 30 m² was evaluated from three distances from the application area and 4 exposure times. The highest volatilization damage values were recorded when the temperature was 25ºC. The soil moisture had influence on the experiment 1, being greated damage when it was wet but was not clear effect on the experiment 2. As regards the formulations used, there was a greater effect on volatilization damage with 2,4-D, dimethylamine y Dicamba, with respect to others. The exposure period had a clear effect being the plants exposed inmediatdy after application and those who remained longer, those most affected by volatilized gases. In the field it was found that 2,4-D choline, did not cause volatilization damage beyond 3 m instead of; and that 2,4-D dimethylamine did so up to 20 m from the application area. No clear effects were found regarding wind direction and the layout of the plants are the different directions.