Balanço de energia e evapotranspiração do capim mombaça sob sistema de pastejo rotacionado

Abstract

In the current scenario of climate changes, researches indicate that the livestock is one the of highest activities contributing to the Greenhouse Gases Emissions (GGE) due to deforestation to expand the pasture areas. In front of this scenario, the irrigation of pasture can to intensify the use of the pasture. However the appropriate management of the irrigation requires the determination of the evapotranspiration to subsidize the decisions about when, how and how much to irrigate avoiding excess consumption of water and energy and other problems related to inadequate irrigation management. In this context, it is aimed to quantify the energy balance by Bowen Ratio method and the evapotranspiration of Mombaça grass irrigated under rotated pasture system at the experimental site of the Universidade Estadual do Norte Fluminense Darcy Ribeiro, in the city of Campos dos Goytacazes, RJ. An automatic micrometeorological station on the pasture area was installed, measuring the fluxes of energy over the crop during the 2010 fall/winter period. On average, the fluxes of latent heat, sensible heat and soil heat represented 66, 23 and 12 % of the net radiation, respectively. The average evapotranspiration of the grass Mombaça was 3.87 mm day-1, with a maximum of 8.93 mm day-1 and a minimum of 0.43 mm day-1.