Exploring soil microbial 16S rRNA sequence data to increase carbon yield and nitrogen efficiency of a bioenergy crop

Abstract

Crop residues returned to the soil are important for the preservation of soil quality, health, and biodiversity, and they increase agriculture sustainability by recycling nutrients. Sugarcane is a bioenergy crop that produces huge amounts of straw (also known as trash) every year. In addition to straw, the ethanol industry also generates large volumes of vinasse, a liquid residue of ethanol production, which is recycled in sugarcane fields as fertilizer. However, both straw and vinasse have an impact on N 2 O fluxes from the soil. Nitrous oxide is a greenhouse gas that is a primary concern in biofuel sustainability. Because bacteria and archaea are the main drivers of N redox processes in soil, in this study we propose the identification of taxa related with N 2 O fluxes by combining functional responses (N 2 O release) and the abundance of these microorganisms in soil. Using a large-scale in situ experiment with ten treatments, an intensive gas monitoring approach, high-throughput sequencing of soil microbial 16S rRNA gene and powerful statistical methods, we identified microbes related to N 2 O fluxes in soil with sugarcane crops. In addition to the classical denitrifiers, we identified taxa within the phylum Firmicutes and mostly uncharacterized taxa recently described as important drivers of N 2 O consumption. Treatments with straw and vinasse also allowed the identification of taxa with potential biotechnological properties that might improve the sustainability of bioethanol by increasing C yields and improving N efficiency in sugarcane fields.

Straw preservation reduced total N2O emissions from a sugarcane field

“…(), Pitombo et al . () and Wang et al . (), among others, have used the emissions from non‐fertilized areas as background emissions to calculate the fertilizer EF.…”

“…Specifically, in a sugarcane field, Pitombo et al . () observed that straw increases the abundance of Anaeromyxobacter sp., a taxon noted as an important reducer of N 2 O to N 2 . Under temperate conditions, Congreves et al .…”

Crop residue harvest for bioenergy production and its implications on soil functioning and plant growth: A review

“…Field measurements of the effects of crop residue harvest on GHG emissions are still limited in Brazil and over the world (Carmo et al, 2013;Baker et al, 2014;Jin et al, 2014;Signor et al, 2014;Pitombo et al, 2015). Most studies on this issue have used model simulations (Searchinger et al, 2008;Davis et al, 2012;Campbell et al, 2014;Liska et al, 2014;Zhao et al, 2015;Cardozo et al, 2016), as well as life cycle analysis assessments Bordonal et al, 2012Bordonal et al, , 2015.…”

Contribution of soil respiration to the global carbon equation

“…Major enzymes in soils include amylase, ␤-glucosidase, cellulase, chitinase, dehydrogenase, phosphatase, protease, and urease and are produced by various microbes (Dick and Tabatabai, 1984;Gupta et al, 1993;Makoi and Ndakidemi, 2008). Although new DNA sequencing technologies have made it possible to investigate microbial community composition (Torsvik and Øvreås, 2002;Cong et al, 2015;Hartmann et al, 2015;Pitombo et al, 2015), we have limited knowledge of the details of soil enzymes, such as their amounts, types, distribution, and efficiency, and little is known of individual microbial species and the corresponding enzyme(s) produced. The importance of soil enzymes to ecosystem functions, including soil respiration, has been reviewed by Makoi and Ndakidemi (2008).…”