phosphorus loss – Livestock and Poultry Environmental Learning Community

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Purpose

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

Dexter.Watts@ars.usda.gov

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 http://aurora.auburn.edu/bitstream/handle/11200/44267/Gypsum%20Bulletin_2013.pdf?sequence=2

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.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

What did we do?

We have collected water quality and land use data from plot- and field-scale experiments throughout the South (AR, GA, MS, NC, OK, and TX). The water quality data provide information on runoff rates, phosphorus concentrations, and phosphorus loads. The land use data provide information on both management practices, including the amount of phosphorus applied as fertilizer and/or manure and tillage, as well as inherent properties such as rainfall, soil series, etc. Once we obtained this information, we used the data to run the Agricultural Policy / Environmental eXtender (APEX), Texas BMP Evaluation Tool (TBET), and Annual Phosphorus Loss (APLE) models, in both uncalibrated and calibrated modes.

What have we learned?

Models predicted runoff accurately, but were unable to predict sediment or phosphorus losses accurately in many cases. Not surprisingly, models performed better when calibrated but even so predictions were problematic for particular locations and constituents (e.g. runoff in NC under no-tillage conditions and sediment at many sites).

Future Plans

We continue to determine factors affecting the poor predictions of certain constituents (e.g. sediment or phosphorus) in different data sets and models. Calibration will continue for APEX and TBET. In addition, state phosphorus indices are being run for each data set. The results from each state’s phosphorus index will be compared against the modeled data as well as other state indices in order to learn if models such as APEX, TBET, and/or APLE can better determine field phosphorus losses than the indices. Final recommendations will be provided to USDA-NRCS.

Acknowledgements

Thanks to our sponsor, USDA-NRCS grant 69-3A75-12-182.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.