Influence of flue gas desulfurization gypsum on phosphorus loss in pine bark substrates

Authors: BARTLEY, PAUL - Auburn University; ERBRICK, L - Auburn University; KNOTTS, M - Auburn University; Watts, Dexter; Torbert, Henry - Allen

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2023
Publication Date: 1/24/2023
Citation: Bartley, P., Erbrick, L., Knotts, M., Watts, D.B., Torbert III, H.A. 2023. Influence of flue gas desulfurization gypsum on phosphorus loss in pine bark substrates. Agriculture. 13:283. https://doi.org/10.3390/agriculture13020283.
DOI: https://doi.org/10.3390/agriculture13020283

Interpretive Summary: Flue-gas desulfurization (FGD) gypsum, a waste product of coal-fired electrical utility plants, has been shown to effectively reduce phosphorus runoff. This study evaluated the efficacy of FGD gypsum to reduce P leaching in horticultural media. The greatest P leaching occurred in the control substrates containing only pine bark and fertilizer. The addition of FGD gypsum at 2.5, 5, and 10% (v/v) reduced the total P collected in leachate by 47, 59, and 70%, respectively. Results indicate that FGD gypsum can be amended with pine bark substrates to effectively reduce P leaching in short-term crops.

Technical Abstract: Flue-gas desulfurization (FGD) gypsum, a waste product of coal-fired electrical utility plants, has been shown to effectively reduce phosphorus (P) runoff in many agricultural systems. However, its applications in horticultural production systems have been insufficiently researched resulting in limited industry adoption. To evaluate the efficacy of FGD gypsum to reduce P leaching in horticultural media, pine bark substrates were amended with FGD gypsum at 2.5, 5, and 10% (v/v). A controlled-release fertilizer was incorporated into the treatments to supply P. The greatest P leaching occurred in the control substrates containing only pine bark and fertilizer. The standard pine bark substrate treatment, containing lime and micronutrients, reduced total P leaching by 35% and should be considered a best management practice. The addition of FGD gypsum at 2.5, 5, and 10% (v/v) reduced the total P collected in leachate by 47, 59, and 70%, respectively. Gypsum amendments increased potassium leachate concentrations, but elevated potassium levels normalized after ~20 days. With little to no effect on substrate physical properties or pH, FGD gypsum can be amended with pine bark substrates to effectively reduce P leaching in short-term crops.