Phosphorus runoff from soils receiving liquid dairy and swine manures amended with mine drainage residual

Authors: Church, Clinton; HEDIN, ROBERT - Consultant; Bryant, Ray; WOLFE, AMY - Consultant; SPARGO, JOHN - Pennsylvania State University; Elkin, Kyle; Saporito, Louis - Lou; Kleinman, Peter

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2021
Publication Date: 7/6/2021
Citation: Church, C., Hedin, R.S., Bryant, R.B., Wolfe, A.G., Spargo, J.T., Elkin, K.R., Saporito, L.S., Kleinman, P.J. 2021. Phosphorus runoff from soils receiving liquid dairy and swine manures amended with mine drainage residual. Applied Engineering in Agriculture. 37(2):351-358. https://doi.org/10.13031/aea.13715.
DOI: https://doi.org/10.13031/aea.13715

Interpretive Summary: Application of manures to croplands is a time-tested method of enriching the soils with N, P, and micronutrients, but with the implication that P runoff from manures plays an important part in eutrophication, farmers are experiencing increasing pressures and regulation to not apply animal manures to fields that are already overloaded with P. The concept of solving one industry’s problem with another industry’s problem is attractive, but uncommon. Since mine drainage residual (MDR) has been shown to reduce soluble P in soils, drainage ditches, and in an engineered treatment system, we sought to test whether MDR was effective at reducing P in runoff during simulated rainfall events. We found that amending dairy manure with MDR resulted in reduced flow weighted DP concentrations and P loads in runoff, but did not observe the same effect with swine manure. This study underscores the importance of testing under simulated field conditions before making manure management recommendations.

Technical Abstract: Application of manures to croplands is a time-tested method of enriching the soils with N, P, and micronutrients. Due to increasing problems with eutrophication of streams and other water bodies however, and the implication that P runoff from manures applied to fields plays an important part in that eutrophication, farmers are experiencing increasing pressures and regulation to not apply animal manures to fields that are already overloaded with P. If the soluble P component of manure can be decreased before it is land-applied, the potential for P runoff losses should be lessened. The concept of solving one industry’s problem with another industry’s problem is attractive, but uncommon. Mine drainage residual (MDR) has been shown to reduce soluble P in soils and drainage ditches, and has been shown to be an effective chemical treatment in an engineered treatment system that removes P from liquid manures. We therefore sought to test whether amending liquid manures with MDR was effective at reducing P in runoff during simulated rainfall events under controlled conditions. We found that amending dairy manure with MDR resulted in reduced flow weighted DP concentrations and P loads in runoff, but did not observe the same effect with swine manure, despite seeing even better results with swine manure than with dairy manure in a dosing/WEP test. Therefore, while it is clear that the amendment of MDR to manure slurries is able to reduce water extractable P (WEP), a simple dosing/WEP test does not necessarily predict that P loss during runoff will be reduced as a result of the practice. This study underscores the importance of testing under simulated field conditions before making manure management recommendations.