Date of Graduation

Fall 2006

Degree

Master of Science in Geospatial Sciences

Department

Geography, Geology and Planning

Committee Chair

Robert Pavlowsky

Keywords

phosphorus, soil, water quality, lawns, land use

Subject Categories

Hydrology | Soil Science

Abstract

Eutrophication of surface waters due to high phosphorus (P) concentrations is an important water quality concern in Greene County, Missouri. Phosphorus enrichment has been linked to a variety of non-point sources including runoff from both agricultural and urban land uses. Soil P has been shown to be a source of P in runoff. The differences in soil P among different land uses may provide insight into which land use contributes more P in runoff. This study examines the soil composition, geochemistry and total P concentration of surface soil (0-5cm) in four land uses in Greene County, Missouri. The land uses sampled were residential lawns, city parks, agricultural pastures, and undisturbed forest. The amount of P extracted by de-ionized (DI) water from each land use was also examined. Total P concentrations for all land uses ranged from 250 to 1200 ppm P. Mean P concentrations did not differ significantly (α=0.05) among land uses. Total P was highly correlated with organic matter (OM) for all land uses, indicating that OM is both a significant source of P and a primary sink for P. Organic Matter was used as the primary variable for regression models predicting TP. A mean of 4.05% of the total P in lawns was extractable by de-ionized water. This is significantly higher (α=0.05) than the mean DI water extractable P in the other land uses. This suggests that lawns may contribute more P per unit area to storm runoff than the other land uses examined. The relationship of TP to the % of DI water extractable P was curvilinear for lawns, parks and forested sites indicating a maximum limit of P sorption by runoff water. However, the same relationship was linear for agricultural sites. 75% of sampled lawns had a TP concentration between 300 and 700 ppm. Within this range lawns can contribute a significantly greater percentage of P to runoff water.

Copyright

© Timothy R. Davis

Open Access

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