Changing patterns in fertilizer use : proceedings of a symposium sponsored by the Soil Science Society of America and held at the Palmer House in Chicago, Illinois, February 14 and 15, 1968. Editorial committee: L. B. Nelson [and others] / Nelson, Lewis B. (Lewis Bailey), 1914- ed. Soil Science Society of America. Fertilizers Congresses. S631 .C45 631.4 NEC Includes bibliographies. Madison, Wis. : Soil Science Society of America, c1968. c1968. 1968 Text xiv, 466 p. : eng