Gypsum as a Best Management Practice for Reducing P loss from Agricultural Fields

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Phosphorus loss from agricultural fields fertilized with poultry litter may contribute to eutrophication of nearby rivers, lakes, and streams. It has been suggested that gypsum can be used as a soil amendment to reduce P loss from these fields. Also, a new USDA-NRCS National Conservation Practice Standard 333 “Amending Soil Properties with Gypsum Products” has recently been created to promote conservation through gypsum use.

What Did We Do?

Field studies were conducted to evaluate the influence of gypsum on reducing P loss from both hayfields and row crops fertilized with poultry litter. Simulated rainfall was created to evaluate the effectiveness of gypsum on reducing P loss in successive runoff events occurring after poultry litter applications during the growing season.

What Have We Learned?

Results showed that gypsum can reduce the loss of dissolved P with surface water runoff from both hayfields and row crop systems. In addition, applying gypsum to grass buffer strips at the edge of an agricultural field could also be an effective management practice for P loss reduction. Gypsum reduced dissolved P loss in successive runoff events after poultry litter application regardless of timing, suggesting that the effect is persistent and will not diminish over a growing season. These findings suggest that gypsum use as a soil amendment has promise for reducing P loss from agricultural fields.   

Future Plans

Future plans are to determine the most effective gypsum rate needed to reduce P loss from both row crop and hayfields systems.

Corresponding author (name, title, affiliation)

Dexter B. Watts, Research Soil Scientist, USDA-Agricultural Research Service located at the National Soil Dynamics Laboratory in Auburn, AL

Corresponding author email address

Other Authors 

H. Allen Torbert, Research Soil Science, USDA-Agricultural Research Service located at the National Soil Dynamics Laboratory in Auburn, AL.

Additional Information

Watts, D.B., J.B. Hess, S.F. Biligili, H.A. Torbert, J.L. Sibley, and J.D. Davis. 2017. Flue gas desulfurization gypsum; Its effectiveness as an alternative bedding material for broiler production. Journal of Applied Poultry Research. 26:50-59.

Watts, D.B., G.B. Runion, and K.S, Balkcom. 2017. Nitrogen fertilizer sources and tillage effects on cotton growth, yield and fiber quality. Field Crops Research. 201:184-191.

Watts, D.B., and H.A. Torbert. 2017. Influence of three application yearly application yearly application of FGD gypsum and poultry litter on surface water runoff. Soil Science. 182:18-27.

Torbert, H.A., R.L. Chaney, and D.B. Watts. 2017. Potential adherence of FGD gypsum to forage as a consideration for excessive ingestion by ruminants. Journal of Environmental Quality. doi:10.2134/jeq2016.07.0279 (In Press).

Watts, D.B., and H.A. Torbert. 2016. Influence of FGD gypsum on reducing soluble P in successive runoff events from a Coastal Plain Bermudagrass Pasture. Journal of Environmental Quality. 45:1071-1079.

Watts, D.B. and W.A. Dick. 2014. Sustainable uses of FGD gypsum in agricultural Systems. J. Environ. Qual. 43:253-262.

Chen, L., D. Kost, Y. Tian, X. Guo, D.B. Watts, D. Norton, R.P. Wolkowski, and W.A. Dick. 2014. Effects of gypsum on heavy metals in soils and earthworms. J. Environ. Qual. 43:263-272.

Torbert, H.A. and D.B. Watts. 2014. Impact of FGD Gypsum application on water quality in a Coastal Plain soil. J.  Environ. Qual. 43:273-280.

Watts, D.B. H.A. Torbert, and C.C. Mitchell. 2013. Gypsum use to reduce P loss for agricultural fields. Alabama Experiment Station Publication. Bulletin no: 680 availiable at

             Watts, D.B. and H.A. Torbert. 2009. Impact of gypsum applied to buffer strips on reducing
              soluble P in surface water runoff. J. Envron. Qual. 38:1511-1517.

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