Location: Northwest Irrigation and Soils ResearchTitle: Recommending soil copper thresholds for potato production in Idaho Author
Submitted to: Extension Publications
Publication Type: Experiment Station
Publication Acceptance Date: 2/27/2013
Publication Date: 2/27/2013
Citation: Moore, A., Satterwhite, M., Ippolito, J.A. 2013. Recommending soil copper thresholds for potato production in Idaho. Extension Publications. WERA-103 Committee, Nutrient Digest,5(1):p.6-7. Interpretive Summary:
Technical Abstract: A rising concern with the application of dairy wastes to agricultural fields is the accumulation of copper in the soil. Copper sulfate from cattle footbaths is washed out of dairy barns and into wastewater lagoons. Potato growers are concerned about this issue, as many of the predominant dairy producing areas in Southern Idaho are also in Idaho’s established potato production regions. The objective of this project was to evaluate potato growth and copper plant uptake for potatoes grown under low, moderate, and excessively high soil copper concentrations. This study was conducted in 2011 in a greenhouse setting at the USDA ARS Kimberly Research Station. To establish an effective copper response curve, 6 rates of copper sulfate (0, 100, 200, 300, 400, and 500 mg/kg soil) were applied to either a Portneuf silt loam or a Wolverine sand. Treatments were replicated four times in a complete randomized block design. Root copper concentrations increased rapidly at relatively low soil copper concentrations for the Wolverine sand. In contrast, root copper concentrations appear to level off at soil copper concentrations of 100 mg/kg for the Portneuf silt loam, suggesting that copper toxicities are likely a much greater issue on sandy soils than on silty soils. We recommend potato production soil extractable threshold copper levels to be 25 and 375 mg/kg for sandy and silty soils, respectively. Producers are urged to test for extractable copper in soils receiving copper containing wastewater.