1 1 10 Firman E. Bear Primary Author A.F. Camp Additional Author H.D. Chapman Additional Author H.P. Cooper Additional Author O. Wesley Davidson Additional Author Leroy Donald Additional Author G.N. Hoffer Additional Author G.V.C. Houghland Additional Author H.A. Jones Additional Author Wesley P. Judkins Additional Author B.A. Krantz Additional Author J.E. McMurtrey, Jr. Additional Author Werner L. Nelson Additional Author E.R. Parker Additional Author E.R. Purvis Additional Author George D. Scarseth Additional Author J.J. Skinner Additional Author Norman J. Volk Additional Author mixed material Washington D.C. The American Society of Agronomy 1949 img334.jpg.jpg