Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Geology

Supervisor

Webb, Elizabeth

2nd Supervisor

Corcoran, Patricia

Joint Supervisor

Abstract

Terroir describes a sense of place that can give a unique flavour to wines grown in different environments. We explored the role of soil in the terroir at Canada’s most southern vineyard, Pelee Island Winery. This study examined the abundance of major nutrients, trace and rare earth elements of minerals and plant extractable nutrients from 19 soils across the vineyard to a depth of 2 m. We found that bedrock does not influence the element content of Pelee Island soils, the parent materials of the soils are tills and there are geochemical, mineralogical and grain size differences between the two soil types on the island. Nutrient distribution throughout the soil profile was controlled by soil weathering with organic matter concentrating most nutrients in surface soils. Agricultural and anthropogenic influences had minimal effects on soil nutrient concentrations.

Summary for Lay Audience

Pelee Island is the southernmost point and has the longest growing season in Canada making it an ideal place to grow grapes to produce quality wines. We examined the elemental concentrations of the soil minerals and nutrients in the soils easily mobilized by plants (plant extractable nutrients) in order to understand variations in grape productivity across the island. This work will lead to a better understanding of how the soil contributes to the terroir, or sense of place that contributes to the flavours of Pelee Island wines. The aims of this study were to determine if bedrock has any influence on soil composition, to distinguish geochemical differences between the two main soil types on the island – Brookston and Toledo, and to understand how soils processes and agricultural and anthropogenic influences affect nutrient distribution within the soil profiles across Pelee Island. Results from the geochemical analysis conclude a few important findings. First, bedrock does not influence the composition of Pelee Island soils. Second, weathering intensities between Brookston and Toledo soils differ causing differences in elemental distributions throughout their soil profiles. Brookston soils are shallower and less leached resulting in higher abundance of Ca in surface soils and lower abundances of Fe and Mn in deep soils compared to Toledo soils. Third, nutrients used by plants are generally highest in surface soils where they are held by organic matter. Lastly, anthropogenic (i.e. airborne pollutants) and agricultural (i.e. fertilizers) influences had minimal effects on soil nutrient concentrations. These results will enable Pelee Island Winery to enhance their soil management practices and improve grape quality to produce quality wines.

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