Lake Erie, phosphorus, and microcystin: Is it really the farmer's fault?

Abstract

The size of the harmful algal blooms in western Lake Erie is strongly correlated with agricultural phosphorus (P) loading from tributaries. Despite farmers' efforts to reduce sediment-bound P loadings and fertilize using current guidance, the media and public have singled them out as the culprit in Lake Erie re-eutrophication. In this paper, two farmer surveys were used to evaluate if farmers in the Lake Erie region follow P fertilizer recommendations, and we also review historic and current P management guidance provided by the scientific community and agricultural industry. The majority (56% to 80%) of farmers apply P fertilizers at or below the current fertility recommendations. Wholesale agronomic changes (e.g., no-tillage adoption, crop cultivar advances, and fertilizer application and formulation) have occurred since current fertilizer recommendations were developed. Although crop P uptake mechanisms have not changed, these agronomic changes have altered P cycling in soil and water. Based on these results, it is time that the scientific community and agricultural industry acknowledge that our current guidance may be contributing to eutrophication. We must ask whether or not we have (1) developed appropriate fertility guidance, (2) developed and recommended appropriate practices to protect water quality, (3) adequately considered "the law of unintended consequences" in conservation recommendations, and (4) focused too much on short-term economic outcomes while disregarding environmental quality. Improved understanding, reconsideration of traditional recommendations, and wider farmer adoption of the most effective practices are needed to develop a sustainable agricultural system in the Western Lake Erie Basin that produces needed commodities while preserving ecosystem integrity.