Influence of tebuthiuron and vinasse under soil microbiota activity in sugarcane crop

Tebuthiuron is an herbicide used in sugarcane crops and can cause great environmental impact due to its high persistence and toxicity in soil. Thus, an organic compound addition influences the environmental behavior of this molecule and could increase its sorption and degradation. Vinasse is used in fertigation and this research aimed to evaluate microbial metabolism in soil cultivated with sugarcane with tebuthiuron and vinasse applications. Experimental design was completely randomized by 2x4 factorial scheme linked to tebuthiuron recommended dose (zero and 1.0x) and to vinasse volume generally used in crops (zero, 0.5x, 1.0x and 2.0x). Soil microbial respiration was performed in triplicate by Bartha and Pramer respirometric method and biodegradation activity was monitored by CO2 determination weekly until 51-day evaluation period. Control treatment presented the lowest CO2 production. The highest rate was observed when tebuthiuron and twice vinasse volume were present. However, results showed that there was no statistical difference between treatments with tebuthiuron independent of vinasse. Vinasse addition significantly increased the CO2 production and it favored soil microbiota activity. Therefore, results suggested that tebuthiuron presence did not cause interference in soil microbial activity represented by CO2 production. Moreover, microorganisms metabolic rate increased in vinasse presence especially in higher concentration.