Abstract
The production and emission of CO2 in native, pasture and cultivated areas is a result of microbiological activity and mineralization of organic matter, and depends on favorable environmental factors, such as temperature, availability of water and of land use. The results of this work show that the no tillage system (NT) has the potential to mitigate 37.7% of C-CO2 efflux from cultivation of soy compared to conventional tillage (CT). The temperature of the soil accounted for 65% of the variability of the flux of CO2-C in CT. The variation of soil moisture explained 73 and 51% of the flux of CO2-C in CT and NT, respectively. These results indicate that soil moisture and soil temperature were controlling factors of CO2-C emissions from soil to atmosphere because these parameters directly affect soil microbial activity. The results also show that the active pasture had the highest outflows of soil CO2-C to the atmosphere in relation to forests and degraded pasture in Western Para. Furthermore, it was shown that both the pastures and forests have seasonality in the fluw, which mainly related to precipitation patterns and water potential between soil and air. We observed a strong correlation between the efflux and soil moisture of both capoeira and in the pastures, as the soil temperature was a controlling factor of the active efflux only in the pasture. The average fluw of CO2-C obtained in pasture active was 218.9 mg C m-2 h-1 value of 40.7% higher than the primary forests and 155.5 mg C m-2 h-1. Finally, the results presented here suggest that the conventional tillage and pasture management are activities strongly associated to human enhance biogeochemical changes in the balance of carbon in these ecosystems, since the efflux of CO2-C is related to soil primary productivity of these ecosystems. Key words: Greenhouse effect, land use change, carbon cycle, soil CO2-C efflux.
Highlights
The concentration of greenhouse gases (GHG) in the atmosphere has increased substantially in recent years as a result of anthropogenic activities
There was no significant occurrence of drought, which maintained adequate levels of moisture in the soil, so it is assumed that this variable was not limiting to microbial activity responsible for the CO2-C efflux
This study found a high coefficient of determination (r2=0.65) and high significance (P
Summary
The concentration of greenhouse gases (GHG) in the atmosphere has increased substantially in recent years as a result of anthropogenic activities. The atmospheric concentrations of carbon dioxide (CO2) have all increased since 1750 due to human activity. In 2011, the concentrations of these three gases were 391 ppm, 1803 ppb and 324 ppb, which exceeded pré-industrial levels by 40, 150 and 20%, respectively. The concentrations of CO2, CH4 and N2O substantially the highest concentrations recorded in the ice cores during the last
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