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Ammonium-oxidizers dynamic in Atlantic Forest soils: impact of forest-to-pasture conversion and nitrogen fertilization

Grant number: 19/19145-5
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): January 01, 2020
Status:Discontinued
Field of knowledge:Biological Sciences - Microbiology
Principal Investigator:Tsai Siu Mui
Grantee:Luis Fernando Merloti
Home Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The nitrification process has a significant importance in regulating the N availability in soil, leaching and denitrification process. The soil nitrification is performed by specific groups of Bacteria and Archaea, that may exhibit different patterns according to different land use and soil management. In contrast to other Brazilian biomes, there is little information about the diversity of microbial communities in Atlantic Forest soils and the functional role played by these microorganisms under effect of anthropogenic actions as forest-to-pasture conversion. In addition, considering that most grasslands in Brazil are composed by Urochloa and fertilized to increase plant development, little know about how the use of nitrogen and Urochloa genotypes change the nitrifying microbial communities under tropical soil conditions. Moreover, the contribution of each group of bacteria and archaea in the nitrification remains unclear, especially under varying conditions N sources in soil. Through three combined studies, this research seeks to elucidate the behavior of potential and active nitrifying microorganisms, according to different land uses in Atlantic Forest region, and in soils under effect of different Urochloa genotypes and N sources. The first study will be based on two soil collections in the Atlantic Forest biome in a native forest, degraded pasture and conserved pasture, where the behavior of the nitrifying community under these different land uses will be investigated. In the second study, through a greenhouse experiment, the effects of Urochloa genotypes and N sources on the active nitrifying soil microbiota will be investigated. In addition, the third study will be a microcosm experiment that will be conducted with the soils used in second study in order to unravel the individual contribution of bacteria and archaea in the nitrification process under effect of N sources. This research proposal intends to offer advances in the characterization of nitrifying microorganisms' role in Atlantic Forest biome and to elucidate the land use change impact on this microbial community. In addition, this research will elucidate the effect of genotypes and nitrogen fertilizers on the active nitrifying community, bringing relevant information to tropical environments. Also, it is expected to generate relevant information for the selection of appropriate agronomic strategies to: improve the use of N in agricultural systems, reduce the negative impact of N on the environment and improve land use encouraging the recovery of degraded pastures. (AU)