ABSTRACT.- Irrigated rice fields are major sources of two important greenhouse gases (GHG), methane and nitrous oxide. As an initial step towards obtaining local information, emissions of CH4 and N2O from rice paddy soil were measured by the static chamber technique in greenhouse and field experiments conducted in eastern Uruguay. In the greenhouse experiment, the effect of two flooding moments (21 and 45 days after emergence) and nitrogen fertilization (0 and 50 kg N ha-1) on gas emissions was studied. Early flooding and nitrogen fertilization tended to increase N2O emissions.

ABSTRACT.- Irrigated rice fields are major sources of two important greenhouse gases (GHG), methane and nitrous oxide. As an initial step towards obtaining local information, emissions of CH4 and N2O from rice paddy soil were measured by the static chamber technique in greenhouse and field experiments conducted in eastern Uruguay. In the greenhouse experiment, the effect of two flooding moments (21 and 45 days after emergence) and nitrogen fertilization (0 and 50 kg N ha-1) on gas emissions was studied. Early flooding and nitrogen fertilization tended to increase N2O emissions.

Las cianobacterias pueden producir cianotoxinas altamente tóxicas para la salud humana y animal. Si bien éstas se asocian al período estival, en los últimos años en Uruguay se han registrado durante todo el año, especialmente en cuerpos de agua lénticos como lagunas, tajamares y embalses.

El clima es uno de los factores más importantes en determinar el crecimiento y el desarrollo de animales destinados a la producción de alimentos y fibras. ---- 1. Introducción. Estrés calórico:importancia para el animal (producción ganadera y lechera), el productor, la sociedad y el ambiente. -- 2. Situación actual. -- 3. Tecnologías propuestas. -- 3.1. Sombra natural. -- 3.2. Sombra artificial. -- 4. Mejoras a partir de la provisión de sombra en sistemas de producción animal. --

El carbono orgánico del suelo representa un pilar fundamental para el desarrollo de la agricultura sostenible a nivel local, siendo el principal indicador de la calidad del suelo y de su potencial productivo. Adicionalmente, los suelos contienen la mayor reserva terrestre de carbono (C) a nivel global; por lo tanto, su secuestro tiene el potencial de reducir los gases de efecto invernadero y contribuir a la lucha contra el cambio climático. ---- 1. Importancia del carbono orgánico del suelo a nivel local y global. -- 1.1.

Rice in southern South America is mainly associated with livestock production in rotation with pastures of three to four years in length, but there is interest in intensifying production by increasing the frequency of rice, introducing new crops, or shortening the pasture in the rotation. However, little is known about the impact of this perturbation on agroecosystems resilience. In 2012, a long-term experiment was established in the main rice-producing area of Uruguay to study the impact of the intensification of rotations on the sustainability of rice systems.