Future developments in soil science research : a collection of SSSA golden anniversary - Boersma, L. L.,; Elrick, D. E.,; Corey, R. B.,; Cheng, H. H.,; Tucker, T. C.,; Rutledge, E. M.,; Unger, P. W.,; Foster, N. W.,; Kincheloe, S.,; Hsu, P. H., (Soil Science Society of America, Inc., 1987)