Dominant glacial landforms of the lower Great Lakes region exhibit different soil phosphorus chemistry and potential risk for phosphorus loss

Authors: PLACH, JANINA - University Of Waterloo; MACRAE, MERRIN - University Of Waterloo; Williams, Mark; LEE, BRAD - University Of Kentucky; King, Kevin

Submitted to: Journal of Great Lakes Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2018
Publication Date: 7/25/2018
Citation: Plach, J.M., Macrae, M.M., Williams, M.R., Lee, B.D., King, K.W. 2018. Dominant glacial landforms of the lower Great Lakes region exhibit different soil phosphorus chemistry and potential risk for phosphorus loss. Journal of Great Lakes Research. 44:1057-1067. https://doi.org/10.1016/j.jglr.2018.07.005.
DOI: https://doi.org/10.1016/j.jglr.2018.07.005

Interpretive Summary: Soil physical and chemical properties vary considerably across the landscape and can have a large influence on nutrient loss. In this study, we examined differences in soil properties across the Lake Erie watershed. Soil samples were collected from fields in southwestern Ontario, Canada, northeastern Indiana, and northwestern Ohio, US and represented soils from the dominant glacial landforms (hummocky coarse-textured till-plain, lacustrine and fine-textured till-plain) found within the Lake Erie watershed. Results showed that there were significant differences in both physical (e.g., soil texture) and chemical (e.g., soil phosphorus concentrations) soil properties within the two regions of the Lake Erie watershed, which likely result in differences in soil phosphorus retention and transport. Findings indicate that in addition to agricultural management practices, the natural landscape may play a large role in determining the potential risk of phosphorus loss. Therefore, when developing appropriate management strategies to minimize phosphorus loss, regional soil properties need to be carefully considered.

Technical Abstract: Phosphorus (P) losses from agricultural soils are a growing economic and water-quality concern in the Lake Erie watershed. While recent studies have explored edge-of-field and watershed P losses related to land-use and agricultural management, the potential for surficial and subsurface soils to retain or release P to runoff across the watershed has not been examined. A field-based study comparing eight agricultural fields in contrasting glacial landscapes (hummocky coarse-textured till-plain, lacustrine and fine-textured till-plain) showed distinct physical and geochemical soil properties influencing inorganic P (Pi) partitioning throughout the soil profile between the two regions. Fields located on the coarse-textured till-plain in central Ontario, Canada had calcareous soils with the highest Pi concentration stored in an acid-soluble pool. In contrast, loosely to moderately soluble and reducible pools generally comprised a greater proportion of surficial and subsurface soil Total-Pi (up to 75%) on the lacustrine and fine-textured till-plain in southwestern Ontario, northeast Indiana, and northwestern Ohio, US. Overall, subsurface soils on the lacustrine and fine-textured till-plain had a greater shrink swell-capacity, likely creating preferential flow to minimize Pi interaction with the more acidic, lower carbonate and lower sorption capacity soils. These differences in soil Pi retention and transport pathways demonstrate that in addition to management, the natural landscape may exert a significant control on how Pi is mobilized throughout the Lake Erie watershed. Further, results indicate that careful consideration of region-specific hydrology and soil biogeochemistry may be required when designing appropriate management strategies to minimize Pi losses across the lower Great Lakes region.