Anais do XXXV Congresso Brasileiro de Ciência do Solo
TRACE GAS FLUXES FROM INTENSIVELY MANAGED RICE AND SOYBEAN FIELDS ACROSS THREE GROWING SEASONS IN THE BRAZILIAN AMAZON
RAIMUNDO COSME DE OLIVEIRA JUNIOR(1); MICHAEL KELLER(2); PATRICK CRILL(3); TROY PATRICK BELDINI(4); PLINIO BATISTA DE CAMAARGO(5); JOOST VAN HAREN(6); 1 - EMBRAPA AMAZONIA ORIENTAL; 2 - US FOREST SERVICE; 3 - STOCKHOLM UNIVERSITY; 4 - UFOPA; 5 - CENA/USP; 6 - ARIZONA UNIVERSITY;
The emission of gases that may potentially intensify the greenhouse effect has received special attention due to their ability to raise global temperatures and possibly modify conditions for life on earth. The objectives of this study were the quantification of trace gas flux (N2O, CO2 and CH4) in soils of the lower Amazon basin that are planted with rice and soybean, and the relation of this flux to soil physical and chemical parameters and to precipitation. This study was conducted in agricultural fields planted with rice (Oryza Sativa) and soybean (Glycine max), located near the cities of Belterra and Santarém in western Pará State, Brazil, during the production years of 2005-2007. Measurements were done using static chambers in the field, and samples were analyzed by gas chromatography in the laboratory. Statistical analysis was conducted to determine variation in gas flux in the two crops, and the results show that CO2 flux varied between 305 and 227 mg-C m-2 h-1 under rice, and 243 and 156 mg-C m-2 h-1 under soybean. Flux of nitrous oxide (N2O) under rice varied between 4.5 and 20.4 µg-N m-2 h-1, and under soybean flux variation was between 4.0 and 9.4 µg-N m-2 h-1. Variation in flux of methane (CH4) under rice was between 5.1 and 14.0 µg-C m-2 h-1, and under soybean it was 0.4 and 1.2 µg-C m-2 h-1. These results demonstrate that, during our study period, the rice crop had higher flux for all trace gases than the soybean crop.
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