Masters Theses

Date of Award


Degree Type


Degree Name

Master of Science


Plant, Soil and Environmental Sciences

Major Professor

Gary M. Lessman

Committee Members

V. H. Reich, J. I. Sewell


Various rates of dairy manure, sewage sludge, and NH4NO3 were applied to a Sequoia silt loam and a Whitwell loam for a two year period to determine their relative effects on corn (Zea mays) responses and some chemical properties of the soils, plants, and soil solutions. Application rates of manure and sludge were 0, 9, 18, 36, and 72 metric tons per hectare on a dry matter basis and 0, 112, 224, 448, and 896 kg/ha for NH4NO3. The manure and sludge checks along with all of the NH4NO3 plots received 90 kg/ha of inorganic P and K. Soil samples were taken prior to the application of the amendments and following the yield measurements. Tissue samples were obtained at the six-leaf stage, ear-leaf stage at silking, and when silage data were collected. Water samples were collected during the winter months. Applications of dairy manure were found to be more beneficial in maintaining the soil pH, and increasing soil P and K than the sewage sludge or NH4NO3 treatments. The soil pH was decreased by additions of sewage sludge and NH4NO3, with the inorganic N fertilizer producing the most marked decreases. Nitrate-N and NH4-N concentrations in the plant tissue were generally higher as the result of applying large amounts of NH4NO3, although the highest rates of manure occasionally produced similar levels. Dairy manure applications were also responsible for producing the highest P and K concentrations among the various treatments. However, Zn levels were influenced more by sludge applications than either of the other materials. Applications of NH4NO3 were more influential in producing the highest NO3-N levels in the water samples, while dairy manure application resulted in the highest P and C1 concentrations among the different treatments. The most noticeable responses were noted after two years of application. Heavy rates of sludge had essentially no effect on P in the soil solution samples. Applications of dairy manure resulted in the most vigorous plants during the early stages of plant growth, while those plants from the N check and the 896 kg/ha rate of NH4NO3 plot had a stunted appearance. When grain and silage yields were taken, the data indicated the same general trends, with the best yields occurring at the higher application rates of manure and the lowest from the N check and the heaviest rate of NH4NO3. The cumulative effects of the fertilizer amendments were responsible for the greater differences in the measured responses during the second year of the experiment. In general, the mineral composition of the soil, tissue, and soil solution samples along with the yields was higher during the second year of the experiment.

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