How farmers use and manage nitrogen: Reflections from an LTER fellow

Each year the KBS LTER program awards two graduate students with summer research fellowships. Here Riva Denny describes the research her 2016 summer fellowship supported. Riva is a PhD student working with Dr. Sandra Marquart-Pyatt in the Department of Sociology, Michigan State University.

As a sociology student who studies agriculture and the environment my research looks a little different from most of the research done at the Kellogg Biological Station Long-term Ecological Research (KBS LTER) site. I study the social aspects of nitrogen fertilizer use in US agriculture and the practices that farmers can use to help reduce the amount of nitrogen that is lost to the larger environment in water or as a gas. Excess nitrogen that ends up in water bodies contributes to harmful algal blooms and dead zones such as the one in the Gulf of Mexico. Nitrogen in the form of nitrous oxide is a greenhouse gas that is almost 300 times more powerful than carbon dioxide. As a sociologist, I am interested in what factors influence and motivate farmers’ decisions about when and how they apply their nitrogen, as well as why they use or do not use specific practices to reduce the impact on the environment.

A well-established vegetative buffer in Bear Creek watershed. Thirty years ago the fields came right up to the stream bank. Photo Credit: Riva Denny

A well-established vegetative buffer in Bear Creek watershed. Thirty years ago the fields came right up to the stream bank. Photo Credit: Riva Denny

Nitrogen is one of the key nutrients that plants need to grow, and it is naturally available in limited quantities. Therefore, the addition of nitrogen fertilizer is an important component of achieving high agricultural yields. However, nitrogen is a very mobile element that takes several forms; it can be dissolved in water and leached through the soil or released as a gas, making it hard to manage in an agricultural field. Farmers cannot be sure at any given time how much of the nitrogen they applied remains in the soil. Practices that can help to reduce nitrogen loss include:

1) applying smaller amounts of nitrogen several times during the early growing season,
2) applying different amounts of nitrogen to different parts of the field based on soil type,
3) using cover crops to scavenge and hold nitrogen in the field when no crop is growing, and
4) reducing tillage to increase soil organic matter making it better able to retain nitrogen.

But these practices and others like them come with their own challenges for farmers in terms of equipment costs, the need for new and/or specialized knowledge, and increased weather dependency.

This past summer, thanks to support from a KBS LTER summer fellowship, I worked on two projects to better understand how and why farmers use and manage their nitrogen fertilizer as they do. For one project I built a data set of all the counties in the continental US and used statistical analysis to see if either of three different conservation practices—cover crops, conservation tillage, and no-till—reduced the amount of total fertilizer per acre that was used in 2012. I wanted to see if a greater use of practices that help hold nutrients in the soil is related to farmers using less fertilizer. If this is true, it would mean that there is good potential for these practices to save farmers money and help to protect water quality. I am still refining the analysis, but the results suggest that the two tillage practices may reduce fertilizer use. In June I presented some of my early results at the International Symposium on Society and Resource Management held in Houghton, MI.

My second project involved analyzing 150 farmer interviews that I helped to conduct in 2014 in Iowa, Indiana and Michigan. I examined how a farmer’s environmental knowledge—in this case knowledge about nitrogen and how different nutrient conserving practices work—relates to how he or she manages nitrogen and what conservation practices are seen as beneficial. Guided by the academic literature on environmental knowledge, I looked for four different kinds of knowledge: 1) knowledge about the practice itself (what is it), 2) knowledge about how to do the practice, 3) knowledge about how effective the practice is for its intended purpose (does using the practice actually make a difference, does it do it better than an alternative practice), and 4) knowledge about the social norms and expectations of using the practice (is it a practice that others expect you to use).

Given the large number of interviews, this analysis is still in progress. I presented on the theoretical aspects of this analysis at the Annual Meeting of the Rural Sociological Society held in Toronto, Canada in August.

The LTER summer fellowship also made it possible for me to travel to Iowa in early June to attend the annual meeting of the NC1190 Catalysts for Water Resources Protection and Restoration: Applied Social Science Research Multistate Research Project. This diverse group of social scientists all research issues related to water quality and quantity in different parts of the country. I am not yet formally involved in any of the group’s projects, but it was an excellent opportunity to network and learn about the research they are doing individually and together. The meeting included a trip to the Bear Creek riparian buffer and research site where we saw vegetative buffers, constructed wetlands and saturated buffer strips.

A recently constructed wetland in the Bear Creek watershed. Photo Credit: Riva Denny

A recently constructed wetland in the Bear Creek watershed. Photo Credit: Riva Denny