Resumen
- High quantities of nitrogen (N) fertilizer are used to maintain milk production and stocking rate in specialized dairy system in the Colombian Andes at 2000 to 3400 m above sea level. This production system needs to be re-evaluated to ensure it is financially and environmentally sustainable. Therefore, it is necessary to evaluate new sward alternatives, such as legumes with N fixing capacity, to increase the competitiveness of this system and also to evaluate the N balance in systems based on grazing grass alone or on mixed pastures. For these purpose, the N cycling in grass alone and with a legume (Lotus) was evaluated.