00295nam a2200109Ia 4500008004100000082001800041100002700059245003600086260003000122600002000152650001300172140224s9999    xx            000 0 und d  a631(047.1) N7  aSparks, Donald L., ed.  aAdvances in Agronomy volume 60.  aSan DiegobAcademicc1997  aL.Donald Sparks  aAgronomy