Masters Theses

Date of Award

8-1996

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant, Soil and Environmental Sciences

Major Professor

Michael D. Mullen

Committee Members

Glenn Wilson, Donald Tyler

Abstract

Additions of organic wastes to soils have been shown to induce changes in soil biological, chemical and physical properties. This study was conducted to observe effects various rates of manure may have on biochemical properties. The study was conducted on eighteen plots at the Martin Experiment station. The soil type of these plots is a Loring silt loam (fine-silty, mixed, thermic, Typic Fragiudalf). These eighteen plots received 126,252, 378, or 504 kg manure-N ha-1 or 218 kg N ha-1 as ammonium nitrate each year since May 1991 while the control plots received 0. Soil samples were taken over four sampling dates (May 4, May 25, June 13, and August 5), at depths of 0-5, 5-10, and 10-20 cm. These samples were analyzed for pH, total nitrogen, organic carbon, Mehlich 1 extractable cations (Mg, N, K, and P), total bacterial counts as well as fluorescent Pseudomonads, fungal counts using the Rose Bengal media as well as for one date, cellulose degraders. The results of these enumerations showed higher plates counts in the 0 to 5 cm depth. All the sampling dates were analyzed for various enzymes as well. The enzymes activities analyzed for were acid and alkaline phosphatase, arylsulfatase, L-asparaginase, and βglucosidase. Enzyme activities was highest in the 0 to 5 cm depth, with lower enyzme activity in the 5 to 10 cm and 10 to 20 cm soil depths. Enyzme activities were generally highest in the manure treated soils. This corresponds with generally higher % organic C, % total N, lower C:N ratios and pH in these soils. The pH of the ammonium nitrate treated soils were more acidic than the other treatments, and this resulted in higher C:N ratios, lower bacterial numbers, fungal counts, and lower activities for some enzymes, particularly arylsulfatase and L-asparaginase. Arylsulfatase was negatively affected by the decrease in pH, particularly in the inorganic treatment. Moreover βglucosidase appeared to be positively affected by the organic carbon contents. In short the overall results of this experiment seemed to indicate that the use of organic wastes, such manure, induce positive changes in soil biochemical properties. However, the manure had little effect on the exchangeable cations, (Mg, P, and K), in the beginning of the experiment, however, toward the end of the experiment there was a slight increase in availability.

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