Studies on the N, P2O5 and K2O-application in the mixed sward of alfalfa-grasses-(1)-Effect of nitrogen fertilization on dry matter and nutrition yield of forages in the mixed sward of alfalfa-grasses

abonos nitrogenados abonos npk application rates contenido de materia seca contenido mineral crecimiento croissance crop yield dose d'application dry matter content engrais npk gramineas graminee grasses growth medicago sativa mineral content mixed pastures nitrogen fertilizers npk fertilizers pastizal mixto prairie mixte rendement des cultures rendimiento de cultivos