Date of Award
Doctor of Philosophy
The data presented have been obtained from a combined field and laboratory study conducted on Norfolk sand; this type of soil is prevalent throughout the sand-hill region of the Carolinas and Georgia. Investigations concerning the relative efficiencies of fertilizers and crop residues as sources of nitrogen for corn and cotton have been made. These involved a comparison of legumes used as green manures; i.e., soybeans, velvet beans, and cowpeas, with only the stubble turned; a low-nitrogen fertilizer was applied to the crops grown on the green manure plats, while a high-nitrogen ratio was used on the stubble plats. These two systems of management were used in a rotation of legumes, corn and cotton. Winter fallow following cowpeas was compared with a winter cover;Yields data were obtained, and the carbon and nitrogen status of the soil was determined semi-annually during the two rounds of the three-year rotation;The foregoing study of the effect of a rational soil management and cropping program on the quantity of the crops produced, and the organic matter content of the soil, was in conjunction with an intensive study of the effect of 21 fertilizers of varying ratio, as dictated by the triangle system, on the composition (quality) of soybean hay and seed. The use of the residues under the three systems of management; i.e., (1) the turning of the crop as a green manure, (2) the turning of the mature hay after the seed had been removed, and (3) the turning of the stubble, allowed the study of the combined effect of fertilizers and residues on the organic matter and the pH of the soil;Yields of seed and hay were obtained for the period 1928 to 1933, inclusive. The seed were analyzed for nitrogen and oil during the period 1929 to 1933. The following components of the hay were determined during a four-year period: (1) nitrogen, (2) phosphoric anhydride, (3) potassium oxide, and (4) calcium oxide; soluble ash, R2O3, Mn 3O4, sulphur, and magnesium oxide were determined during a three-year period;These studies have provided information regarding some fundamental problems associated with a fertility program for the Norfolk sand.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
James Edward Adams
Adams, James Edward, "Chemical investigations of the effect of fertilizer ratios and green manures on yields and composition of crops and the organic matter in Norfolk sand " (1936). Retrospective Theses and Dissertations. 13267.