Vinasse and tebuthiuron application to sugarcane soil and its effects on bacterial community and ecotoxicity after natural attenuation

Soil fertility and weed control are fundamental factors for vinasse and herbicide applications in sugarcane crops, however environmental damage can be caused by their continuous and increasing use. Therefore, the present study aimed to analyze the changes in microbial community and ecotoxicological potential of sugarcane soil for different associations of vinasse and tebuthiuron. The experimental design was completely randomized in a factorial scheme 4x2, linked to vinasse volume (V0-0,5-1,0-2,0) and to tebuthiuron recommended dose (H0-1). Thus, different soil samples were analyzed in two periods (initial time and after 51 days of natural attenuation) for the number of bacterial CFU and the phytotoxic effect by ecotoxicity bioassays using lettuce seeds as test organism. Initially, results revealed that vinasse presence increased the number of bacterial colonies in soil, especially when used at higher concentrations. Higher volumes of vinasse also favored plant development at initial time. On the other hand, this benefit was reduced after natural attenuation. Finally, it was found that tebuthiuron dose did not negatively impact the bacterial community or soil ecotoxicity.