What Is the Connection between Phosphorus and Water Quality?
“Phosphorus (P) is an essential element for plant and animal growth and its input has long been recognized as necessary to maintain profitable crop and animal production. Phosphorus inputs can also increase the biological productivity of surface waters by accelerating eutrophication. Eutrophication is the natural aging of lakes or streams brought on by nutrient enrichment. This process can be greatly accelerated by human activities that increase nutrient loading rates to water. Eutrophication has been identified as the main cause of impaired surface water quality (U.S. Environmental Protection Agency 1996). Eutrophication restricts water use for fisheries, recreation, industry, and drinking because of increased growth of undesirable algae and aquatic weeds and the oxygen shortages caused by their death and decomposition.” Reprinted with permission from the author: Sharpley et al., 2003)
The association of P with eutrophication of surface waters has resulted in a significant focus on the role of P in animal agriculture. P-related research in recent years has concentrated on two main areas: reducing P excretion from livestock and application and transport of P on agricultural fields. Lowering dietary P concentration has been a means of reducing P inputs to dairy operations. In 2003, a report indicated that, on average, dietary P concentrations were 34% above recommended levels. Reducing the dietary P concentrations in dairy cattle diets to recommended concentrations has not negatively impacted milk production, health, or reproductive parameters. The economic advantages of reducing P imports to the farm have helped to improve industry acceptance of this management practice and have led dairy producers and nutritionists to reduce the P concentrations in dairy diets. (Reprinted with permission from the author: Harrison et al., 2007).
References
Harrison, J. H., T. D. Nennich, and R. White. 2007. Review: Nutrient management and dairy cattle production. CABI Publishing 2007 (Online ISSN 1749-8848). Available online at http://www.cababstractsplus.org/cabreviews (Verified 14 December, 2010).
Sharpley, A.N., T. Daniel, T. Sims, J. Lemunyon, R. Stevens, and R. Parry. 2003. Agricultural Phosphorus and Eutrophication, 2nd ed. U.S. Department of Agriculture, Agricultural Research Service, ARS–149, 44 pp.
Research Project on Phosphorus Feed Management
A project started in February 2009 to enhance feed management practices to reduce manure phosphorus excretion in dairy cattle. This project takes an “integrated approach” to increase the adoption of reduced phosphorus feeding on dairy farms.
Overall Goal
Improve our accuracy of meeting the phosphorus requirement of the dairy cow without oversupplying phosphorus in the ration by better understanding the availability of phoshorus in feedstuffs (reduce current practices of overfeeding phosphorus to ensure that the animal requirements of phosphorus are met).
Project Funding
This project has been funded by the USDA National Research Initiative Program from 2009 through 2012.
Project Team
Project Director: Katharine Knowlton Virginia Tech Department of Dairy Science
Email: knowlton@vt.edu
Charlie Stallings Virginia Tech Department of Dairy Science
Email: cstallin@vt.edu
Bob James Virginia Tech Department of Dairy Science
Email: jamesre@vt.edu
Mark Hanigan Virginia Tech Department of Dairy Science
Email: mhanigan@vt.edu
Joe Harrison Washington State University, Puyallup
Email: jhharrison@wsu.edu
Sandy Anderson Washington State University, Puyallup
Email: sandra_anderson@wsu.edu
What We Expect to Achieve
- Develop analytical techniques to improve assessment of phosphorus digestion and excretion in lactating cows.
- Evaluate the variation in digestion and excretion of phosphorus-containing compounds in lactating cows using the newly developed analytical techniques.
- Develop and test a model that will more accurately estimate phosphorus digestion and metabolism in lactating cows. The model will be used in dairy cattle ration formulation.
- Develop, implement, and assess an effective information transfer process to encourage adoption of research findings via educational tools and on-farm assessment.
Outreach Opportunities:
Our team is ready and willing to serve as speaker for nutrition conferences on the following topics:
- Using feed management software to improve farm profitability and whole farm nutrient balance – Dr. Bob James Email: jamesre@vt.edu
- Incentive payments to reduce overfeeding of phosphorus – Dr. Charlie Stallings Email: cstallin@vt.edu
- Next generation of precision feeding – Where are we going from here? – Dr. Katharine Knowlton and Dr. Mark Hanigan Emails: knowlton@vt.edu, mhanigan@vt.edu
- Modeling Phosphorus Digestion to Improve Predictions in Ration Balancing Software – Dr. Mark Hanigan Email: mhanigan@vt.edu
Presentations:
Impact of feed management software on feeding management and whole farm nutrient balance of Virginia dairy farms
Robert James, B. E. Cox, C. S. Stallings, K. F. Knowlton, M. Hanigan
Virginia Tech – jamesre@vt.edu
The impact of precision feeding utilizing feed management software on whole farm nutrient balance (WFNB), dietary phosphorus, and feeding management was studied on nine treatment and six control farms selected in four regions of the Chesapeake Bay Watershed of Virginia from 2006 through 2008. Herd sizes averaged 271 and 390 lactating cows, and milk yield averaged 30 and 27 kg/cow/d for treatment and control farms. Crop hectares averaged 309 and 310 for treatment and control farms. Treatment farms installed feed management software between May and October 2006. Data were collected for calendar year 2005 and each calendar year through 2008 to compute WFNB. On treatment farms, up to five feed samples were obtained monthly including each total mixed ration (TMR) fed to lactating cows. Control farms submitted TMR samples every two months. Standard wet chemistry analysis of samples was performed. Feed management data stored in the software were collected monthly from each treatment farm concurrent with feed sampling. Daily overfeeding of all dietary ingredients across treatment farms averaged 1.25% ± 5.86, ranging from -67.28% to +54.57% during the first year of the trial. This corresponded to average daily overfeeding of CP and P of 2.26% ± 6.88 and 1.91% ± 6.39, respectively for 2006. Whole farm nutrient balance did not differ between treatment and control farms for 2006. However, eight of nine treatment herds qualified for incentive payments for limiting P intake to less than 120% of NRC requirements in 2006. Data from 2007 and 2008 indicated that herds utilizing feed management software formulated and fed rations that were within 116% of NRC requirements for P. Data from feed management software revealed that extensive use of by-product feeds and the high nutrient variability of forages contributed to overfeeding of both CP and P. Category: Agricultural BMPs
View slide show
This presentation was presented at the 2011 American Dairy Science Meetings in New Orleans by Partha Ray, M D Hanigan, and K F Knowlton.
Quantification of phytate in dairy digesta and feces using alkaline extraction and HPIC
Publications:
Using Incentive Payments to Reduce Overfeeding of Phosphorus
This poster was presented at the 2010 Land Grant and Sea Grant National Water Conference by Charles C. Stallings, K. F. Knowlton, R. E. James, and M. D. Hanigan.
View Dairy Incentive Poster
Total and inorganic phosphorus content of an array of feedstuffs
This poster was presented at the 2011 American Dairy Science Meetings in New Orleans by Jamie Jarrett, M D Hanigan, R Ward, P Sirois, and K F Knowlton.
Total and inorganic phosphorus content of an array of feedstuffs
Fate of phosphorus in large intestine of dairy heifers
This poster was presented at the 2011 American Dairy Science Meetings in New Orleans by Partha Ray, M D Hanigan, and K F Knowlton.
Fate of phosphorus in large intestine of dairy heifers
Webcasts:
Precision Phosphorus Feeding for Dairy Cows
This presentation was originally broadcast on March 19, 2010. There are four short presentations:
- Dietary Nutrient Management: What Goes In Must Come Out – Dr. Mark Hanigan, Department of Dairy Science, Virginia Tech
- Precision Phosphorus Feeding Incentive Program – Dr. Charles Stallings, Department of Dairy Science, Virginia Tech
- Impact of Feed Management Software on Feeding Management and Whole Farm Nutrient Balance – Dr. Robert James, Department of Dairy Science, Virginia Tech
- Questions and Answers
View Presentation: Precision Phosphorus Feeding for Dairy Cows
Precision Phosphorus Feeding for Dairy Farms
Katharine Knowlton and Jimmy Huffard
During this session on February 7, 2011, Katharine Knowlton of Virginia Polytechnic Institute and State University and Jimmy Hufard, a dairy producer in Virginia, discussed regulations pertaining to phosphorus and how these can affect the dairy farm.
View Presentation: View Presentation of Precision Phosphorus Feeding for Dairy Farms
View Slide Show from presentation:
For an outline of the materials presented, see: Presentation Transcript
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