CO2 flux and Evapotranspiration on Tropical Pasture under Intensive Grazing
Agrometeorology; Greenhouse Effect; Climate Changes; Gas Exchange.
The increase in carbon dioxide (CO2) concentration has profound implications for the global climate. This increase is largely due to various anthropogenic activities, that on the one hand have increased the amount emitted to the atmosphere, mainly from burning fossil fuels and the other have diminished the ability of terrestrial sinks. Most of the CO2 emitted into the atmosphere is absorbed by the oceans, but a considerable portion is absorbed by terrestrial ecosystems. In this context, agricultural production systems have been questioned about the sustainability as regards the emission of greenhouse gases. Thus, to investigate the exchange of energy and mass of various terrestrial ecosystems is very important because it allows the expansion of knowledge to better understand the mechanisms that control the CO2 cycle. Given this, the present study aims to determine the flow of CO2 and evapotranspiration in Brachiaria brizantha pasture grazed by sheep. The experiment is being conducted in the municipality of Macaíba-RN, in Escola Agrícola de Jundiaí, Campus Macaíba of the Universidade Federal do Rio Grande do Norte - UFRN in the experimental area of the Grupo de Estudos em Forragicultura (GEFOR). Data is being collected through the technique of Eddy Covariance Method from systematic measures (frequency of 10 Hz, with 30 minutes outputs). The results in the first six months of study to the net balance of CO2 have demonstrated that had capture of that gas, even in the period of low potential for forage production (~1100 kg/ha in October and November). The sequestration of CO2 increased significantly in February (~2700 kg/ha), during which there was greater rainfall. Durant experimental period were found that Brachiaria brizantha on the climatic conditions of Macaíba-RN was a of CO2 sinks whose accumulated values was higher than 7,0 ton ha-1 that means about 2,0 ton ha-1 of C, with water consumptions of 253 mm.