N-prognosis and N-advice in Aust-Agder 1989-1997

abonos nitrogenados absorption de substances nutritives analyse de sol application rates azote cereales cereals chimie du sol dose d'application extension extension activities feed crops hortalizas leaching legume lessivage du sol nitrogen nitrogen fertilizers noruega norway nutrient uptake nutrition des plantes papa planification planning plant nutrition plantas forrajeras pomme de terre potatoes soil chemistry soil testing solanum vegetables vulgarisation