Assessment of Fertilizer and Manure Application and Impacts in the Western Lake Erie Basin

Session: 41a. - Great Lakes Harmful Algal Blooms Research from Watershed Influence to Ecosystem Effects

John Bratton, Limnotech, [email protected]
Derek Schlea, LimnoTech, [email protected]
Noemi Barabas, Limnotech, [email protected]
Michael Murray, National Wildlife Federation, Great Lakes Regional Center, [email protected]
David Allan, University of Michigan, Sch. For Environment and Sustainability, [email protected]
Matthew Child, International Joint Commission, [email protected]

Abstract

An assessment of fertilizer and manure application and impacts in the Western Lake Erie Basin (WLEB), including the U.S. and Canada, was conducted in cooperation with members of the International Joint Commission Science Advisory Board's Science Priority Committee. Nonpoint agricultural release is understood to be the largest single source of excess nutrients to Lake Erie and the driver of harmful algal blooms. Inorganic fertilizer was found to be the primary source of phosphorus used for agricultural purposes in the study area (typically 70 to 80% of applied P), with manure generated by livestock making up the balance. Note that not all manure generated is applied to cropland. Offshore lake monitoring and lower watershed monitoring are reasonably robust for the region. Numerical models, which can be used to guide management, are handicapped by gaps in watershed characterization, monitoring data, and process understanding. Important drivers of change in nutrient delivery and possibly increased algal blooms include changes in precipitation patterns and increased tile drainage. The role of legacy P in the watershed as a source of P to the lake is unclear. Improving understanding of these components of the system will be important for evaluating alternative actions to reduce algal blooms.

1. Keyword
Lake Erie

2. Keyword
phosphorus

3. Keyword
eutrophication

4. Additional Keyword
agriculture

5. Additional Keyword
fertilizer

6. Additional Keyword
harmful algal blooms