Evaluating the 4R Nutrient Stewardship Concept and Certification Program in the Western Lake Erie Basin

The increase in harmful algal blooms in Lake Erie since the mid 1990s is correlated with an increasing trend in dissolved phosphate loading. A considerable proportion of this dissolved phosphate comes from cropland. This multi-disciplinary research project, initiated in July 2014, aims to quantify the water quality benefits of 4R initiatives in the Western Lake Erie Basin. By January 2017, 37 retail locations reaching almost three million acres, had achieved certification in 4R Nutrient Stewardship.

The efforts of this research project were: 1) Edge-of-field monitoring: Data is being collected from a total of 23 paired sites comparing 4R and other crop and soil management practices. In several peer-reviewed papers published in 2016, major findings included a 45% reduction in dissolved phosphorus (P) concentration in tile drain water from "right place" incorporation of P fertilizer, substantial reduction in P loss from soils very high in P when gypsum ("right source") was applied, and the fact that revisions and modifications are needed to make current risk assessment tools (P Index and SWAT/APEX models) accurate for predicting 4R impacts. 2) Watershed monitoring: In several peer-reviewed papers published in 2016, major findings included: the fact that P loads behave like those of silica suggests that the sources of P are widespread throughout the watershed; the top inch of soil in the Sandusky watershed had an average soil test P 55% higher than the typical agronomic sampling depth, and reducing this stratification is important to achieving watershed-scale P loss reduction; and, one-third of the increase in dissolved P loads since 2002 can be attributed to increased river flow. 3) Watershed modeling: The SWAT model has been adapted to use data on timing and placement of manure and fertilizer P. Data and model runs in this project contributed to the Field to Market water quality metric in the Fieldprint Calculator. 4) Lake ecosystem modeling: A paper published in the Journal of Great Lakes Research showed how the Western Lake Erie Ecosystem Model can be applied to help separate management effects from those of natural variability. 5) Socio-economic surveys: The 2016 survey found that over 80% of farmers express great concern for the ecological health of the lake, and 60 to 90% are willing to consider adopting new practices.

The outreach component of the project included a paper published in the Journal of Great Lakes Research, titled "Building partnerships to scale up conservation: 4R Nutrient Stewardship Certification Program in the Lake Erie watershed." This paper raises the level of awareness of the industry's 4R efforts among the lake science communities.