[A comparative study of the influence of growing techniques on the nitrogen, phosphorus and potassium contents of leaves, in the soils planted with vines [Portugal]]

abonos verdes analyse de tissus analyse statistique azote engrais vert essai farmyard manure feuille fosforo fumier green manures hojas labranza leaves nitrogen phosphore phosphorus portugal potasio potassium pruebas statistical analysis tillage tissue analysis travail du sol trials vitis vinifera