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Washington State University - Puyallup Organic Farming Systems and Nutrient Management

Manure as a Resource


The separation of animal agriculture from crop production has led to accumulation of excess manure on livestock farms. Crop farms can benefit from this manure as a source of nutrients and organic matter, if the manure is suitable for their needs and shipping does not make the cost prohibitive. We have assessed the nutrient values of different sources of manure and their suitability for crop production (see “♣ Predicting Nitrogen Availability for Organic Amendments“). Our publication “♣ Fertilizing with Manure and Other Organic Amendments” is a guide for crop farmers for evaluating manure sources, and testing and applying manure.

Horse Manure and Soil Nitrogen

Horse manure is an abundant, locally available source of organic matter for soils.  A major concern about horse manure is that it can cause a nitrogen deficiency when added to soils, leading to stunted, yellowed crops.  In a study of 36 farms and stables in King County we measured nitrogen levels in horse manure (see: “♣ Horse Manure and Soil Nitrogen).

Managing Dairy Manure to Protect Water Quality

Water quality problems, changing herd management patterns, and increased regulation have made manure management a critical issue for dairy farmers. Our immediate goal is to help dairy farmers improve the use of manure to increase agronomic benefits and reduce the risk of over-application, runoff, and leaching. Our long-term goal is to help farmers identify chronic nutrient imbalances, and develop ways to reduce nutrient imports or increase exports. We have done research on 1) rate and timing of dairy slurry applications to forage grass, 2) pre-sidedress nitrate testing for corn, 3) whole-farm flows on dairies. Manure application rates have traditionally been based on nitrogen, but phosphorus has emerged as the nutrient of concern in many watersheds.


♣ Manure Spreading Advisory Page – Manure Application Risk Management for the Puget Sound.  When can you apply manure anywhere in the Puget Sound region, given current conditions?  Interactive, specs based on: time of year, current weather forecast for your farm, individual field conditions.

♣ Oregon State University Nutrient Management, Dan Sullivan. Focus is on nutrient management for animal manure and other organic by-products.

♣ A Horse Owner’s Guide to Good Stewardship.   R. James, Ohio State University, good soil and water stewardship practices for horse owners.

♣ Environmental Stewardship for Small-Scale Animal Producers. This is a series of fact sheets on topics including manure management, pastures, runoff, protecting water quality, animal mortalities, and environmental stewardship for horse owners. This link includes an opportunity to review these bulletins and share your comments with the authors.


♣ Fertilizing with Manure and Other Organic Amendments (PDF-Online). Bary, A., C. Cogger, and D.M. Sullivan. 2016. Washington State University Cooperative Extension, Oregon State University Cooperative Extension System, US Department of Agriculture. PNW0533.

♣ Estimating Plant-Available Nitrogen Release from Manures, Composts, and Specialty Products (Request pdf e-copy). Gale, E.S., D.M. Sullivan, C.G. Cogger, A.I. Bary, D.D. Hemphill, and E.A. Myhre. 2006. J. Environ. Qual. 35:2321-2332.

♣ Manure on Your Farm: Asset or Liability (PDF-Online). Cogger, C.G. 2004. LPES Small Farms Fact Sheet.

♣ Post Harvest Soil Nitrate Testing for Manured Cropping Systems West of the Cascades (PDF-Online).  Sullivan, D.M. and C.G. Cogger. 2003.EM8832-E. Oregon State University Extension Service.

♣ Supercow: A Liquid Manure Applicator for Small Plot Research (HTML-Online). Bary, A.I., D.M. Sullivan, S.C. Fransen, and C.G. Cogger. 2001. Agronomy J. 93:1344-1345.

♣ Whole-Farm Nutrient Flow and Manure Management (PDF-Online). Cogger, C.G., T.N. Cramer, A.I. Bary, and D.C. Grusenmeyer. 1998.p. 581-586. In Animal Production Systems and the Environment. Des Moines, IA, 19-22 July, 1998.

♣ Sweet Corn (Western Oregon) Nutrient Management Guide (PDF-Online).  Hart, J.M., D.M. Sullivan, J.R. Myers, and R.E. Peachey. 2010.  EM9010-E. Oregon State University Extension Service

♣ Date, Rate, & Place: The Field Book for Dairy Manure Applicators (PDF-Online).  Bary, A.I. and J. Harrison. 2017. PNW 506. Pacific Northwest Extension Publication.

♣ Which Test is Best? Customizing Dairy Manure Nutrient Testing (PDF-Online). Sullivan, D.M., C.G. Cogger, and A.I. Bary. 1997. PNW 505. Pacific Northwest Extension Publication.

♣ Timing of Dairy Manure Applications to Perennial Grass on Well-Drained and Poorly-Drained Soils (Request pdf e-copy). Sullivan, D.M., C.G. Cogger, A.I. Bary, and S.C. Fransen. 2000. J. Soil & Water Conservation. J. Soil and Water Conservation 55:147-152.

♣ Biosolids and Dairy Manure as Nitrogen Sources for Prairiegrass on a Poorly Drained Soil (Request pdf e-copy). Sullivan, D.M., S.C. Fransen, C.G. Cogger, and A.I. Bary. 1997. J. Prod. Agric. 10:589-596.