Using sugar cane vinasse as a biofertilizer: effects on soil microbial community due to periodical application

摘要

Bioethanol production from sugarcane generates by-products such as vinasse, with a high content of organic matter and potassium. While vinasse can be used as a fertilizer, its effect on the soil and its microbiota is unknown. In this work, we evaluated the effect of systematic vinasse application on microbial communities of soils used for sugarcane cultivation. The assays were carried out in the field and controlled conditions using the same soil type previously irrigated only with water or with vinasse. In the field, soil samples were taken prior to summer irrigation and one month later during years. No significant differences were found in the abundance of most microbial populations nor in the microbial activity by the vinasse treatment. However, in some sampling dates, populations of phosphate solubilizing bacteria, Bacillus spp. and ammonifying bacteria were significantly lower in soil with systematic vinasse irrigation compared to the control. Under controlled conditions, the treatments included two doses of vinasse and a control without vinasse. The abundance of heterotrophic bacteria and fungi increased in both soils with vinasse addition compared to the control, and at 180 days an increase in ammonifying bacteria was observed. Although microbial populations remained higher with the vinasse treatments, their activity decreased over time, with more evident effects on soils without application history. According to our results, vinasse application could have temporary effects on microbial communities, depending on soil type and doses, so local research is needed to create technical standards that regulate the use of vinasse on agricultural soils.