Anais do XXXIV Congresso Brasileiro de Ciência do Solo

SOIL PHYSICAL, CHEMICAL, AND BIOLOGICAL PROPERTIES UNDER SOYBEANS AND IN AN ADJACENT RAINFOREST IN AMAZONIA

RAIMUNDO COSME DE OLIVEIRA JUNIOR⁽¹⁾; TROY PATRICK BELDINI⁽²⁾; MICHAEL KELLER⁽³⁾; PLINIO CAMARGO⁽⁴⁾; PATRICK CRILL⁽⁵⁾;
1 - EMBRAPA AMAZONIA ORIENTAL; 2 - UFOPA; 3 - USFOREST SERVICE; 4 - CENA-USP; 5 - STOCKHOLM UNIVERSITY;

Land use change in the Amazon basin has occurred at an accelerated pace during the last decade. This study investigated soil chemical, physical, and biological properties in a field under cultivation of soy and rice, and an adjacent primary rain forest. Increases in soil bulk density, exchangeable cations, and pH were found in the soy field soil. In the primary forest, soil microbial biomass and basal respiration rates were higher, and the microbial community was metabolically more efficient. The sum of basal respiration across the A, AB and BA horizons on a mass per area basis ranged from 7.31 to 10.05 Mg CO2-C ha-1.yr-1, thus yielding estimates for total soil respiration between 9.6 and 15.5 Mg CO2-C ha-1.yr-1 across sites and seasons. The estimates of heterotrophic respiration made help to further constrain the estimates of autotrophic soil respiration and will be important in determining effects of future land-use and climate change in Amazonian ecosystems.

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