Effectiveness of flue gas desulfurization gypsum in reducing phosphorus solubility in poultry litter when applied as an in-house amendment

Authors: CHAKRABORTY, DEBOLINA - Auburn University; PRASAD, RISHI - Auburn University; Watts, Dexter; Torbert, Henry - Allen

Submitted to: Waste Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2023
Publication Date: 8/22/2023
Citation: Chakraborty, D., Prasad, R., Watts, D.B., Torbert III, H.A. 2023. Effectiveness of flue gas desulfurization gypsum in reducing phosphorus solubility in poultry litter when applied as an in-house amendment. Waste Management. 171(1):1-9. https://doi.org/10.1016/j.wasman.2023.08.014.
DOI: https://doi.org/10.1016/j.wasman.2023.08.014

Interpretive Summary: Phosphorus (P) runoff from agricultural lands amended with manure has become a major environmental challenge, especially in high density poultry producing regions where enormous amounts of poultry litter (PL) is generated. Gypsum has been used effectively as a soil amendment for reducing the risk of P loss. However, there is no information available about the effectiveness of gypsum in reducing P loss when used as a litter amendment in the broiler house. Hence, the objectives of this study were to understand a) effectiveness of flue gas desulfurization (FGD) gypsum used a litter amendment in reducing P loss risk after surface application; and b) distribution of P in inorganic (Pi) and organic (Po) forms in FGD treated and untreated litters. An experiment was performed where broiler chickens were raised for five flocks on FGD treated versus untreated litters. Litter was collected at the end of the experiment and were used for sequential water extractions for seven cycles. Phosphorus concentrations were determined in the water extracts to understand P solubility in untreated and FGD treated litters. Phosphorus fractionation of the litter was performed using Hedley procedure to identify bioavailable (Water-P), labile (Labile-P), aluminum/iron chemisorbed P (Fe-Al P), and mineral occluded P (Ca-Mg P). Results indicated significantly higher soluble P in the untreated litters compared to FGD treated litter for the 1st extraction cycle. Fractionation study revealed lower proportion of Water-P and higher proportion of Labile-P and Ca-Mg P in FGD treated versus untreated litters. The FGD treated litters were able to reduce 58 to 67% of soluble P in the 1st water extraction compared to the untreated litters. This study helped in identifying the Pi and Po forms in FGD treated and untreated litters and will play an instrumental role in reducing environmental P mobility from application of PL on agricultural lands.

Technical Abstract: Phosphorus (P) loss from agricultural lands receiving poultry litter has received increased attention in recent years due to its potential for causing environmental degradation. Gypsum can be used as a soil additive to reduce the risk of P loss. Presently, there is no information available about the effectiveness of using gypsum in reducing P loss from litter when used in bedding during chicken production. Thus, an experiment was conducted to evaluate influence of flue gas desulfurization (FGD) gypsum in the bedding material where broiler chickens were raised for five flocks. Results from this study showed that using FGD gypsum in the bedding for chickens can reduce soluble P concentration in the litter (old bedding material containing manure) by 58 to 67%. This will result in significant reductions in P loss once the litter is applied to an agricultural field as a fertilizer.