00257nam a2200097Ia 4500008004100000082002000041100001900061245003300080260003800113300000800151140113s9999    xx            000 0 und d  a631(02)   N2.47  a"Sparks, D.L."  aAdvances in agronomy -vol.47  a1992b Academic PresscCalifornia  a412