Nitrogen fertilisation in tropical pastures: what are the impacts of this practice?

It is estimated that approximately 47% of the world?s ruminant meat and milk is produced in tropical and subtropical regions, with pasture comprising the main food base of these animals. Nitrogen fertilisation is an essential practice for the maintenance of pasture productivity, considering that a deficiency of this nutrient is a primary factor in triggering pasture degradation. In addition to directly influencing the photochemical and biochemical phases of photosynthesis, nitrogen stimulates enzyme activity and the synthesis of enzymes responsible for fixing CO2 (Rubisco in C3 plants and phosphoenolpyruvate carboxylase in C4 plants), thus increasing the efficiency of atmospheric CO2 capture. All of these physiological processes are easily observed macroscopically in the characteristics of forage plants. This review examines the impact of nitrogen fertilisation in tropical pastures on the main components of production systems (soil, plants and animals), describes the results obtained in different situations and highlights the most efficient ways of producing meat without environmental impacts