Analysis of microbial communities in soils under different land uses on the frontier of agricultural expansion in Southwestern Amazonia

Abstract

The Amazon rainforest is the world's largest reservoir of plant and animal diversity, and it has been subjected to especially high rates of land use conversion by agriculture and pasture. Areas of native forest are cleared through slash-and-burn before being converted to their use. This expansion is driven by growing demand for soybeans, primarily by the Asian market recently incorporated into the global economy. This region includes several types of land-uses, since the extraction performed on native vegetation, until the cultivation with different levels of technology for agriculture and livestock. In agriculture, stand out the crop of soybeans, cotton, corn and rice, grown in no-till or conventional form; in livestock, there are pasture areas well managed and others more degraded. In pasture areas the use of Brachiaria (Brachiaria brizantha) is predominant; while in agriculture, is common the use of soybean crop (Glicine max L. Merril) preceded by the succession of corn (Zea mayz L.). This research aims to determine how the land-use change alters the microbial communities present in soil, characterized by native vegetation cover, agricultural management (soybean crop) and pasture at the frontier of agricultural expansion in the southeast Amazon. For this purpose, the taxonomical and functional structure of soil microorganisms will be studied by metagenome through high-throughput next generation sequencing. The microbial community of different land-use systems will be compared in a taxonomic and functional level to better understand the effects of deforestation over the structure of soil microorganisms in this region. Therewith, it is expected to evaluate the hypothesis that changes in land-use alter microbial communities and that change has effect on the microorganisms related to the greenhouse gases emissions, analyzing this way if there is loss of diversity and there is an increase in the presence of genes related to GHG emissions. (AU)