Effect of rotation on the recovery of 15N-labelled fertilizer applied to wheat grown in northern Syria

abonos abonos nitrogenados absorption de substances nutritives azote barbecho cicer arietinum continuous cropping cropping systems cultivo continuo culture continue efficiency eficacia engrais fallow fertilizers lens culinaris nitrogen nitrogen fertilizers nutrient uptake rotation culturale rotational cropping siria sistemas de cultivo syria syrie trigo triticum durum uses usos utilisation wheats