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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.)

Short-term changes in nitrogen availability, gas fluxes (CO2, NO, N2O) and microbial biomass after tillage during pasture re-establishment in Rondonia, Brazil

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Autor(es):
Carmo, Janaina Braga do ; Piccolo, Marisa de Cássia ; Andrade, Cristiano Alberto de ; Cerri, Carlos Eduardo Pellegrino ; Feigl, Brigitte Josefine ; Sousa Neto, Eráclito ; Cerri, Carlos Clemente [7]
Número total de Autores: 7
Tipo de documento: Artigo Científico
Fonte: SOIL & TILLAGE RESEARCH; v. 96, n. 1/2, p. 250-259, Oct. 2007.
Área do conhecimento: Ciências Agrárias - Agronomia
Assunto(s):Florestas   Pastagens   Carbono   Ciclo do nitrogênio   Ecossistema amazônico   Mudança climática   Biomassa
Resumo

Anthropogenic conversion of primary forest to pasture for cattle production is still frequent in the Amazon Basin. Practices adopted by ranchers to restore productivity to degraded pasture have the potential to alter soil N availability and N gas losses from soils. We examined short-term (35 days) effects of tillage prior to pasture re-establishment on soil N availability, CO2, NO and N2O fluxes and microbial biomass C and N under degraded pasture at Nova Vida ranch, Rondônia, Brazilian Amazon. We collected soil samples and measured gas fluxes in tilled and control (non tilled pasture) 12 times at equally spaced intervals during October 2001 to quantify the effect of tillage. Maximum soil NH4+ and NO3- pools were 13.2 and 6.3 kg N ha-1 respectively after tillage compared to 0.24 and 6.3 kg N ha-1 in the control. Carbon dioxide flux ranged from 118 to 181 mg C-CO2 m2 h-1 in the control (non-tilled) and from 110 to 235 mg C-CO2 m2 h-1 when tilled. Microbial biomass C varied from 365 to 461 ug g-1 in the control and from 248 to 535 ug g-1 when tilled. The values for N2O fluxes ranged from 1.22 to 96.9 ug N m-2 h-1 in the tilled plots with a maximum 3 days after the second tilling. Variability in NO flux in the control and when tilled was consistent with previous measures of NO emissions from pasture at Nova Vida. When tilled, the NO/N2O ratio remained <1 after the first tilling suggesting that denitrification dominated N cycling. The effects of tilling on microbial parameters were less clear, except for a decrease in qCO2 and an increase in microbial biomass C/N immediately after tilling. Our results suggest that restoration of degraded pastures with tillage will lead to less C matter, at least initially. Further long-term research is needed. (AU)

Processo FAPESP: 00/08239-2 - Avaliação de sistemas de recuperação de pastagens degradadas na Amazônia: critérios agronômicos, ambientais e econômicos
Beneficiário:Carlos Clemente Cerri
Modalidade de apoio: Auxílio à Pesquisa - Temático