[by W. I. Watkins and others] ; United States Department of Agriculture, Agricultural Research Administration, Bureau of Plant Industry, Soils, and Agricultural Engineering
by A.C. Anderson ... [and others] ; United States Department of Agriculture, Bureau of Chemistry and Soils ; in cooperation with the Louisiana Agricultural Experiment Station
by E. W. Knobel ... [and others] ; United States Department of Agriculture, Agricultural Research Administration, Bureau of Plant Industry, Soils, and Agricultural Engineering