Impacts of land-use change and crop residues on nitrous oxide emission and abundance of soil denitrifiers bacteria

Abstract

In Brazil, eucalyptus has high demand for wood products, while citriculture has important role in the export trade of commodities and Brazilian GDP. Both cultivars have been used on forest fields recently converted to cropland areas, making necessary to understand the impacts of forest-to-agriculture conversion on soil physical, chemical, biogeochemical, and microbiological properties to meet the demands of sustainable agricultural practices. Microorganisms involved in nitrogen cycle play an important role in soil nutrients cycling, and climate regulation by the emission of nitrous oxide (N2O), one of the main greenhouse gases. Thus, we aim to evaluate (i) the relation between physical and chemical characteristics on N2O emission from soil, and (ii) investigate the relation between denitrifier microbial community in eucalyptus- and Citrus-cultivated soils and adjacent areas of native vegetation and chemical characteristics of soil and plant residues on surface soil. For this purpose, the analysis of N2O emission will be performed based on soil from field. Additionally, microcosms analysis will be performed at laboratory under controlled conditions, in order to investigate the influences of soil physical and chemical factors and chemical characteristics of plant residues (forest and crop residues) on soil denitrifier community. Soil genomic DNA will be used as template in amplification reactions with specific primers for three different functional microbial genes associated with denitrification process (nirK, nirS and nosZ). Reactions will be performed using Real Time quantitative PCR assays (qPCR). Statistical analysis of the results will be performed using variance analysis (ANOVA), Tukey test and multivariate statistical analysis. The expected results of this project will allow a more detailed understanding about the impacts of forest-to-agriculture conversion on soil chemical and microbiological properties associated with the denitrification process. (AU)