Study examines factors influencing farmers’ use of nutrient management practices

J. Arbuckle, Sociology and Criminal Justice, 515-294-1497;
Ann Robinson, Agriculture and Life Sciences Communications, 515-294-3066;
CALS News Service

October 16, 2023

AMES, Iowa - A study of Iowa farmers’ use of 4R Plus nutrient management practices offers insights into social, economic, and ecological influences on adoption that operate at both an individual level and within a larger, county-level context.

The 4R approach to agricultural nutrient management aims to ensure use of the “right source” of nutrients at the “right rate,” the “right time” and in the “right place” for efficient use of fertilizers to avoid nutrient loss and maximize farm income. While 4R refers to in-field nutrient management practices, “Plus” refers to in-field conservation practices, such as no-till and cover crops, and edge-of-field conservation practices, including bioreactors or saturated buffers.

“There has been a lot of research looking at adoption of individual 4R Plus conservation practices. However, we think this is the first study that examines a full range of 4R Plus practices,” said J. Arbuckle, professor of sociology at Iowa State University and director of the annual Iowa Farm and Rural Life Poll.

Arbuckle was on the research team who reported findings from the project recently in the Journal of Soil and Water Conservation, with Suraj Upadhaya, now assistant professor of sustainable systems at Kentucky State University, who worked on the project as an Iowa State research scientist, and Lisa Schulte Moore, professor of natural resource ecology and management at Iowa State.

They conducted a multi-level analysis that reflected self-reported data from just over 6,000 farmers across the state from 2015-2019, representing a response rate of 42% out of about 14,000 contacts. Data were gathered on use of 14 different 4R Plus practices and other diverse factors, including information sources, attitudes, demographics and farm characteristics. The responses were analyzed along with county-level data from the same period that assessed several contextual factors which could impact farmer decision-making - average farm income, percent of farmland rented, slope of cropland and rate of participation in crop insurance.

Among the findings:
• 86% of farmers said they had used one or more 4R practice;
• 6% reported they had used three 4R practices (right source, rate and time); and
• Roughly 83% said they had used at least one in-field or edge-of-field “plus” practice.

Not surprisingly, farmers with more positive attitudes toward the Iowa Nutrient Reduction Strategy were more likely to have used many of the practices. The INRS is a strategy centered on voluntary adoption of diverse conservation practices to reduce nutrient losses contributing to water quality impairments across the Upper Midwest and hypoxic conditions in the Gulf of Mexico. Also, farmers with land adjacent to water bodies, such as creeks, streams, rivers or lakes, were more likely to have adopted Plus practices.

Other significant findings of the study:
• Lack of confidence in agronomic capacity to address nutrient losses was negatively associated with use of all the 4R Plus practices, except for the right source;
• Acres of cropland and pasture showed positive associations with use of 4R practices;
• County-level average crop insurance coverage level was negatively related to adoption of both in-field and edge-of-field Plus practices;
• Individuals farming in counties with a higher percentage of rented land were less likely to have adopted right time, right source and edge-of-field practices;
• Farmers in counties with a greater average slope were less likely to adopt nutrient management practices, but more likely to adopt the “plus” conservation practices.

“Many Iowa farmers indicate they still lack confidence in their capacity to reduce nutrient loss despite major efforts to promote nutrient management,” the study’s lead author Upadhaya said. “This points to a continuing need to help farmers gain confidence in their ability to follow 4R Plus stewardship guidelines, which could save them money and improve environmental outcomes.”

Crop insurance, purchased by most row crop farmers in intensively farmed areas in the United States, also may be an obstacle to farmers’ adoption of 4R Plus practices, according to the study.

“Crop insurance is a critically important safety net tool, but we need to make sure that short-term risk management policies do not undermine long-term goals for agricultural sustainability and food security,” Arbuckle said.

The study suggests that new programs, such as the Post-Application Coverage Endorsement (PACE), which reduces financial risks associated with in-season N application, could help mitigate current disincentives discouraging use of nutrient management and other conservation practices.

“This work is important to help us understand how best to tailor policy, research and education to encourage use of nutrient management practices,” said Matthew Helmers, director of the Iowa Nutrient Research Center, which helped fund the study. Other support came from the Nature Conservancy, Iowa State’s Consortium for Cultivating Human and Naturally reGenerating Enterprises (C-CHANGE) initiative, the Iowa Department of Agriculture and Land Stewardship and Iowa State University Extension and Outreach.

This study is unique, due to its innovative multi-level analysis that examined the influence of both individual-level characteristics and county-level contextual factors on adoption behaviors, according to Upadhaya.

“The results are complicated, though, due to the number of predictor variables and conservation practices,” he said. “The relationships between variables were not as consistent as we anticipated, indicating that factors influencing adoption vary among practice types. This area needs additional exploration.”