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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Isotopically constrained soil carbon and nitrogen budgets in a soybean field chronosequence in the Brazilian Amazon region

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Autor(es):
Silva Figueira, Adelaine M. e. ; Davidson, Eric A. ; Nagy, R. Chelsea ; Riskin, Shelby H. ; Martinelli, Luiz A.
Número total de Autores: 5
Tipo de documento: Artigo Científico
Fonte: JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES; v. 121, n. 10, p. 2520-2529, OCT 2016.
Citações Web of Science: 3
Resumo

The impacts of large-scale conversion of cattle pastures to cropland on soil carbon (C) and nitrogen (N) stocks are poorly understood in the Amazon region. The objective of this research was to determine whether soybean cultivation on a previously deforested and pastured soil has changed C and N stocks and dynamics. We sampled a chronosequence of soybean fields in 2009 and again in 2013. We hypothesized that detecting statistically significant changes in total soil C and N stocks would be difficult but that fluxes of C and N through the soil would be sufficiently large to significantly decrease the stable isotope ratios of soil organic matter. We observed statistically significant decreases in the C-13 and N-15 enrichments and C:N ratio. When combined with estimates of crop biomass production, harvest yield, and biological nitrogen fixation, these measurements provided sufficient constraints for C and N budgets to infer modest rates of net change in soil N (+15 to +27kgNha(-1) yr(-1)) and soil C (-0.15 to -0.30Mg C ha(-1) yr(-1)) in the top 10cm of soil. These results indicate that this intensive soybean cropping system is having minimal impacts on N loss to the environment but likely is a small net source of C to the atmosphere. (AU)

Processo FAPESP: 08/51343-7 - Expansão da fronteira agrícola na Amazônia e suas implicações na ciclagem de N nos sistemas naturais adjacentes
Beneficiário:Adelaine Michela e Silva Figueira
Linha de fomento: Bolsas no Brasil - Doutorado