Solving the phosphorous pollution puzzle to improve water quality in the Great Lakes region

Researchers at Michigan State University are implementing strategies that start at the source of the phosphorous pollution issue in the Great Lakes — farmers’ decision-making on fertilizer use.

When fertilizers run off into nearby streams, rivers and lakes, phosphorus in the fertilizer can degrade water quality, promote harmful algal blooms and, in extreme cases, cause massive fish kills. These effects also have impacts on recreational activities such as swimming as well as industries such as fishing.

The state of Ohio and countless other stakeholders around the Great Lakes are working to stop the flow of fertilizer into the water. Included in that group are researchers at Michigan State University (MSU), who are implementing strategies that start at the source of the issue — farmers’ decision making on fertilizer use. Cloé Garnache, assistant professor in the MSU Department of Agricultural, Food and Resource Economics, is the lead researcher in two nationally funded grants to understand why and how farmers decide how much fertilizer to use on their crops.

The first grant, co-sponsored by the Economic Research Service (ERS) and the National Institute of Food and Agriculture (NIFA), aims to understand the source of the algae problem by using insights from psychology and behavioral economics to test whether farmers could be nudged into applying less fertilizer. The second grant, funded by NIFA, looks at how all aspects of the phosphorus problem are connected to help identify the most cost-effective policies.

“If we want to understand how water quality is impacted by agricultural runoff, we have to think about all the pieces of the puzzle,” Garnache said. “And the first piece is farmer behavior.”

Hired as a part of the MSU Global Water Initiative, Garnache and her team of economists and crop scientists are focusing on understanding how farmers make decisions. The key questions are why some farmers use more fertilizer than necessary to maximize crop growth, and whether social comparisons could persuade farmers to apply less fertilizer.

“We believe it might have something to do with social norms and how farmers perceive they are doing relative to their peers,” Garnache said. “For example, can knowing that your peers apply less fertilizer make you reconsider how much fertilizer you apply on your field?”

A growing body of evidence shows that consumers respond to social norms, but little work has been done with farmers. Garnache and her team want to uncover whether social norms can help reduce the use of fertilizer.

The MSU team will survey row crop farmers in Michigan, informing some of them of their neighbors’ nutrient management practices and comparing their behavior to those who are not provided the social comparisons information.

“Using a randomized controlled trial, we’ll be able to measure the extent to which social norms can be effective at nudging farmers into being better stewards of the environment,” Garnache said.

The insights gained will feed into the second project. The researchers will combine the results on why farmers do what they do and whether they can be nudged into different behaviors with other factors — such as the surrounding ecosystem, the phosphorus that goes from farms to streams to lakes to beaches, and the people who recreate, fish or use the water for industry — to form a comprehensive, integrated model.

“We want to put all those pieces together to estimate the cost of farmers reducing phosphorus and link it to the benefits of that reduction in terms of cleaner beaches, more fish and better ecosystems,” Garnache said.

The team plans to build an integrated model that includes farmers, crops, hydrological systems, aquatic ecology, fish biology and the newly found factors such as farmer decision-making. That integrated model will allow them to see how a small change in farmer behavior can significantly affect beach-going or fishing or performance of numerous water-based industries.

The overarching goal of these two grants (worth $750,000) is to give insightful information to policymakers, who can then make informed policies related to fertilizer use and improved water quality in the region.

“This work would not be happening without the MSU WaterCube program,” Garnache said. “It was instrumental in helping us put together a team of experts that spans three colleges and five departments. The WaterCube program provided us with a platform to meet people from other disciplines, and then it gave us the resources to work together and to get ideas like this started and proposals drafted.”

These proposals focused on the Great Lakes region are just two of many projects that Garnache is exploring. Interested in the valuation of environmental amenities, Garnache is studying things such as how wildfires can affect the value of nearby properties and how a good snow year affects places such as the Upper Peninsula, with its strong, snow-based tourism industry.

“The unifying goal in all of my projects is to help policymakers understand environmental amenities,” Garnache said. “It’s up to them to manage and protect our resources, and I want my work to help them.”

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