True recovery coefficient of (15) N urea sprayed on wheat canopies at flowering | Coefficient reel d'utilisation du (15)N uree pulverise sur des couverts de ble a floraison

abonos nitrogenados application foliaire cereal crops cultivos de cereales efficiency eficacia engrais liquide fertilisation fertilizer application feuille floraison flowering foliar application hojas leaves liquid fertilizers metabolism metabolisme metabolismo nitrogen fertilizers nutrition physiology physiologie de la nutrition triticum urea uree