Linking soil microbial community dynamics to N2O emission after bioenergy residue amendments

Abstract

Vinasse is a major by-product generated by the sugarcane

biofuel industry. It is a source of microbes, nutrients and organic matter

and often it is recycled as fertilizer. The research described in this thesis

addressed how vinasse and sugarcane straw added together with N fertilizer affect the soil microbial community structure and function and N2O emission. The application of vinasse, N fertilizer and combined application of vinasse plus N fertilizer changed in the soil microbial community. However, these changes were restricted to a short period. Vinasse and straw induced changes in the soil microbial community composition and potential functions, but straw additions triggered the stronger changes. The invasive bacteria present in the vinasse were unable to survive in the soil, except of members of the Lactobacillaceae family. Treatments with vinasse and N fertilizer applications increased N2O emissions and the microbial processes involved in N2O production were nitrification by ammonia-oxidizing bacteria (AOB) and archaea and denitrification by bacteria and fungi. However, amoA-AOB (Nitrosospira sp) and fungal nirK were the most important genes related to N2O emissions. These results highlight the importance of vinasse management and can be used as a reference to develop good management practices.