Date of Graduation

5-2018

Document Type

Thesis

Degree Name

Bachelor of Science in Biological Engineering

Degree Level

Undergraduate

Department

Biological and Agricultural Engineering

Advisor/Mentor

Haggard, Brian E

Committee Member/Reader

Runkle, Benjamin

Committee Member/Second Reader

Miller, David

Abstract

In recent years, nutrient release into flood waters and runoff has been a major concern within the Illinois River watershed, as well as nationwide. This study investigated whether there was a change in the release rate of soluble reactive phosphorous (SRP) into overlying water from soil cores incubated at different temperatures. Soil cores were incubated at 4.4°C, 20°C, and 32°C. After inundation, water samples were taken periodically over a seven-hour period and SRP measured. Following the drainage of the water, the upper 5 cm soil from each core was dried and analyzed for Mehlich III-extractable and water-extractable P. The results showed that SRP release at 32°C (63.5 mg m-2 h-1) was significantly greater (p < 0.01) than those at 4.4°C (18.4 mg m-2 h-1) and 20°C (24.1 mg m-2 h-1). The equilibrium SRP concentration seen in the flood water was also 2.5 times greater in the 32°C (0.54 mg L-1) treatment group (p < 0.01). The SRP concentrations and flux were not related to extractable P in the soil, which did not vary across treatment groups (p > 0.05). The study found that an increase in temperature can lead to higher SRP concentrations and a faster SRP flux. Based on these results, soil amendments to mitigate P release would be the most effective if applied before the increased rainfall typical of the spring and rise in temperature of the late spring and summer months.

Keywords

Soluble Reactive Phosphorus; runoff; Mehlich III-extractable; incubated

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