Subsurface phosphorus and nitrogen loss following liquid dairy manure and commercial fertilizer application on a clay soil in northwest Ohio

Authors: King, Kevin; Hanrahan, Brittany; LABARGE, GREG - The Ohio State University; Stinner, Jedediah; Rumora, Kathryne - Katie

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2023
Publication Date: 3/27/2023
Citation: King, K.W., Hanrahan, B.R., Labarge, G.A., Stinner, J.H., Rumora, K.R. 2023. Subsurface phosphorus and nitrogen loss following liquid dairy manure and commercial fertilizer application on a clay soil in northwest Ohio. Journal of Environmental Quality. 52(4):859-872. https://doi.org/10.1002/jeq2.20478.
DOI: https://doi.org/10.1002/jeq2.20478

Interpretive Summary: The use of animal manures and commercial fertilizer continues to be at the center of many conversations regarding water quality and conservation policy. However, there is a lack of data on the water quality impacts of the two fertilizer sources. Four plus years of data using a paired design from an Ohio crop production operation showed that there was a small but significant increase in the daily dissolved reactive phosphorus and nitrate-nitrogen loss from liquid dairy manure when compared to commercial fertilizer. These findings should help conservationists and practitioners seeking to improve water quality and also inform conservation policy as it relates to fertilizer source.

Technical Abstract: Nutrient source has been the focus of much debate regarding the re-eutrophication of Lake Erie, despite that only 20% of nutrients applied to crops in the Western Lake Erie Basin (WLEB) originate from organic sources. However, limited data and assessments exist on the water quality comparison between organic and inorganic sources in crop production systems. Subsurface tile drainage, nitrate-nitrogen (NO3-N), dissolved reactive phosphorus (DRP) and total phosphorus (TP) losses following equal phosphorus (P) based applications of liquid dairy manure and monoammonium phosphate (MAP) were assessed using a before-after control-impact design and four years of data from a paired field system located in northwest Ohio, USA. No significant differences (p > 0.05) were detected in drainage discharge volumes or TP loads between the control and impact sites. However, statistically significant increases (p < 0.05) were measured for mean daily DRP, NO3-N, and TN loads from the dairy manure site. While significant, mean daily DRP differences between commercial (MAP) and organic (liquid dairy manure) treatments were on the order of 0.01 g DRP/ha, while mean daily N differences were approximately 0.01 kg N/ha. However, when accumulated across a watershed, these seemingly small losses may be important to water quality issues. These findings also help to inform nutrient management stewardship as it relates to nutrient source. Furthermore, additional research across a range of soil characteristics and cropping managements should be explored as well as the impacts of other livestock manure nutrients.