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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #236455
Title: Copper sulfate foot baths on dairies and crop toxicities – What are the risks?

Author
item MOORE, AMBER - UNIVERSITY OF IDAHO
item Ippolito, James

Submitted to: University of Idaho Miscellaneous Publication
Publication Type: Popular Publication
Publication Acceptance Date: 11/30/2008
Publication Date: 12/5/2008
Citation: Moore, A., Ippolito, J.A. 2008. Copper sulfate foot baths on dairies and crop toxicities – What are the risks?. Nutrient Digest, Nutrient Management Newsletter for Idaho, University of Idaho Extension. 1(2):1,5.

Interpretive Summary:

Technical Abstract: A rising concern with the application of dairy wastes to agricultural fields is the accumulation of copper (Cu) in the soil. Copper sulfate (CuSO4) from cattle foot baths are washed out of dairy barns and into wastewater lagoons. The addition of CuSO4 baths has been reported to increase Cu concentration significantly in manure slurry from 4.8g/1000 liters to 88.6g/1000 liters. This liquid waste is subsequently utilized to irrigate crops; here in agricultural fields the potential to increase available soil Cu is realized. Following irrigation, the majority of Cu is typically adsorbed to soil organic matter, with additional Cu being bound to clay particles, converted to copper hydroxide, or remaining as a plant available form. Our preliminary results of increasing Cu additions to corn or alfalfa showed that DTPA-extractable Cu concentrations ranging from 1 to 154 ppm in a calcareous soil had no effect on alfalfa or corn silage biomass yields. However, plant survival was drastically impeded at concentrations of 323 ppm and greater. It should be mentioned that Cu application rates used in our study exceeded rates typically observed for liquid dairy manure applications. However, repeated liquid dairy manure applications could potentially raise soil and subsequently plant Cu content to a threshold considered hazardous to feed to domestic livestock. While more studies are needed to develop an official threshold for Cu in Idaho soils, based on what we know so fare it would be advisable to cease Cu additions to soils with greater than 100 ppm extractable Cu.