Conditional Causal Mediation Analysis of Factors Associated With Cover Crop Adoption in Iowa, USA

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Lee, Danhyang
Nowatzke, Laurie
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Zhu, Zhengyuan
Director of the Center for Survey Statistics and Methodology and Professor
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As leaders in statistical research, collaboration, and education, the Department of Statistics at Iowa State University offers students an education like no other. We are committed to our mission of developing and applying statistical methods, and proud of our award-winning students and faculty.
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Iowa Nutrient Research Center
The Iowa Nutrient Research Center was established to pursue science-based approaches to evaluating the performance of current and emerging nutrient management practices and providing recommendations on practice implementation and development. Publications in this digital repository are products of INRC-funded research. The INRC is headquartered at Iowa State University and operates in collaboration with the University of Iowa and the University of Northern Iowa. Additional project information is available at:
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The Iowa Nutrient Reduction Strategy is a statewide effort that aims to encourage voluntary adoption of conservation practices by farmers to reduce the loss of nitrogen and phosphorus that contribute to water quality impairments in the Upper Midwest and drive hypoxic conditions in the Gulf of Mexico. This work is an analysis of the first 2 years (2015–2016) of a 5‐year survey of Iowa farmers. We employ causal mediation analysis to examine the direct and indirect effects of key explanatory variables (e.g., information sources, nutrient management influences, involvement in watershed management activities, and conservation technical assistance) and two causally ordered mediators (farmers' awareness of and attitudes toward the Nutrient Reduction Strategy) on cover crop use. Results showed that participation in watershed activities and receipt of cost share or technical assistance had positive direct effects on cover crop use, while low levels of perceived nutrient loss mitigation self‐efficacy had a negative direct effect. Information and influence of public sector soil and water conservation entities had positive indirect effects on cover crop use through awareness and attitudes, while influence of private sector agribusiness entities had negative indirect effects through those mediators. These results suggest that current strategies such as engaging farmers in watershed management activities and public sector cost share and technical assistance are increasing adoption of cover crops, but the data also point to a need to increase engagement with private sector actors to help them improve their effectiveness as conservation technical assistance providers.


This article is published as Lee, Danhyang, J. Gordon Arbuckle, Zhengyuan Zhu, and Laurie Nowatzke. "Conditional Causal Mediation Analysis of Factors Associated With Cover Crop Adoption in Iowa, USA." Water Resources Research 54, no. 11 (2018): 9566-9584. doi: 10.1029/2017WR022385. Posted with permission.

Mon Jan 01 00:00:00 UTC 2018