Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Environmental Applied Science and Management

First Advisor

Andrew Laursen

Second Advisor

Lynda McCarthy

Third Advisor

Vadim Bostan

Abstract

The effects of municipal biosolids on nitrogen-fixing bacteria were assessed in a three month soil incubation study. Treatments included reference agricultural soils, soil amended with municipal biosolids or manure, and biosolids without soil. Nitrogen-fixation rates in reference and manure-amended soil were similar, and lower than in biosolids treatments; respiration rates showed similar trends. At test termination there was no difference between soil treatments for nitrogen-fixation, but some enhanced respiration in the biosolids-amended soils. Community structure was assessed using Biolog EcoPlates™ and denaturing gradient gel electrphoresis with a nitrogen-fixing gene (nifH). EcoPlate™ carbon utilization patterns corresponded with activity measures, with no difference among soil treatments at test termination. Nitrogen-fixing gene patterns showed a potential shift in community structure of biosolids-amended soils three months post-amendment. In general, the effects on the activity and structure of nitrogen-fixing communities were largely temporary; however, this study evaluated a one-time biosolids application. The potential for cumulative effects requires further investigation.


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