Microbial diversity involved in the cycling of nitrogen in soils cultivated with sugarcane in São Paulo state

Abstract

Sugarcane is the most important agricultural crop in São Paulo State, Brazil. There are three cultivated regions, two considered older and one undergoing recent crop expansion, each under different land-use systems. Considering crop productivity and sustainability, the soil microbial community's role in the nitrogen cycle is of great importance, since nitrogen is essential for plants. However, little is known about the microbial community related to biogeochemical cycling in sugarcane cultivated soils. Thus, we aim to describe the microbial diversity in sugarcane cultivated soils in São Paulo State, Brazil, encompassing the following groups related to the nitrogen cycle: ammonium-oxidizing bacteria and archaea, N-fixing bacteria, and denitrifying bacteria. We propose culture-independent methods to quantify these communities with real-time PCR (qPCR), analyze the structure of these microbial communities with terminal restriction fragment length polymorphism (T-RFLP), and determine phylogenetic affiliation of these organisms by pyrosequencing. Finally, microbiological data are correlated with soil physical-chemical attributes, resulting in a study of microbial diversity related to the nitrogen cycle in these soils.