Options Magazine, Winter 2022: Nutrient runoff from croplands is threatening the integrity of natural waters. Researchers devised sustainable management practices to protect against phosphorous overload in Lake Erie.

Though phosphorus is crucial to boosting crop yields, its runoff can cause nutrient over-enrichment in agricultural watersheds. This can cause irreversible damage to aquatic ecosystems and their biodiversity, for instance, through toxic algae blooms.

Lake Erie in the United States is a prominent example of this occurring. With major American cities such as Cleveland and Detroit on its banks, Lake Erie has suffered through numerous instances of harmful algal blooms in recent decades.

In a study published in the journal Sustainability, Matthias Wildemeersch and his colleagues applied stochastic modeling to come up with sustainable management practices that balance crop yield optimization with environmental protection. Their model also takes into account changing weather trends as a result of climate change.

The results of their study show that to achieve the objective of reliably reducing phosphorus loads in Lake Erie, a coherent package of nutrient management policies is necessary, including the reduction of phosphorus inputs (around 30%), higher adoption of cover crops throughout the near- and mid-century, and land allocation for less nutrient-intensive crops.

“Over multiple decades, there have been continuous efforts to combat the eutrophication of Lake Erie,” explains Wildemeersch, a researcher in the Exploratory Modeling of Human-natural Systems Research Group of the IIASA Advancing Systems Analysis Program. “Our intuition was that uncertain weather variations were very important in estimating future nutrient runoff in the surface waters. What we found is that, ultimately, ignoring these variations leads to largely insufficient mitigation efforts.”

by Jeremy Summers