Composted Horse Manure and Stall Bedding Pilot Project

Final Report for OW11-315

Project Type: Professional + Producer
Funds awarded in 2011: $39,410.00
Projected End Date: 12/31/2012
Grant Recipient: Snohomish Conservation District
Region: Western
State: Washington
Principal Investigator:
Caitlin Price Youngquist
Snohomish Conservation District
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Project Information


Recreational and professional horse owners contribute to maintaining agricultural open space and supporting the agricultural infrastructure and local economy. However, they have historically been overlooked as contributors to animal agriculture, and they do not qualify for most local Farm Bill programs or grants to improve their operations. There has also been very little regulatory oversight of the industry. As a result, many horse owners lack basic knowledge about manure and nutrient management and the impacts of their actions on water and soil quality.

Composting manure and stall bedding at high temperatures eliminates pathogens and parasites and reduces odors and vector attraction. It is not unusual for dairy farms to use composted or aged manure as bedding. The "Composted Stall Bedding Pilot Project" was developed to study and promote the use of compost as alternative horse stall bedding and encourage horse owners and managers to think more creatively about manure management. The objectives were reduced bedding use and improved land management practices at equine facilities in Snohomish County.


Snohomish County in Washington State is home to thousands of recreational and professional horse owners. The piles of stall waste generated from some of the larger equine facilities are phenomenal in both size and potential environmental risk. The cost of disposal is prohibitive for many of the larger horse facilities, and as a result, the manure and stall waste piles up. It is not uncommon for piles to be on the scale of 500 to 1,000 cubic yards. Dumping manure and stall waste over the edge of a ravine or using it to fill in low areas is also common practice.

Bedding purchase and disposal represents a significant cost to both professional and recreational horse owners. The primary bedding material used in this region is wood pellets or wood shavings. These materials are dusty and acidic and can be especially irritating to the skin and respiratory tract when horses are kept confined in stalls.

Horse owners play an important role in maintaining agricultural open space and supporting the agricultural infrastructure and local economy. However, they have historically been overlooked as contributors to animal agriculture. Most do not qualify for local Farm Bill programs or grants to improve their operations and do not understand the importance of manure and nutrient management. Historically there has been less regulatory oversight of the industry, and most people are unaware that horse manure management practices can significantly impact water quality and animal health.

Composting manure at high temperatures eliminates pathogens and parasites, stabilizes nutrients and reduces odors and vector attraction. It is not unusual for dairy farms to use composted bedding. So the question was asked: if cows, then why not horses? The "Composted Stall Bedding Pilot Project" was developed to encourage horse owners and managers to think more creatively about managing manure, reducing bedding use and improving land management practices.

Project Objectives:
  1. Conduct on-farm trials to demonstrate the effectiveness of compost as an alternative to conventional horse stall bedding materials (i.e. shavings and wood pellets).
    Develop an education and outreach program that promotes compost as an alternative stall bedding material and composting as a responsible manure management strategy.


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  • Peter Moon


Materials and methods:

The Snohomish Conservation District (SCD) worked with ten commercial and two private barns during the course of this project. Collaboration with large and small facilities allowed us to test composted bedding in different environments and under a variety of management styles. For the purpose of this report, equine facilities are referred to as “barns” and owners or managers are referred to as “managers.”

Phase I: Making Composted Bedding on the Farm

Five micro-bin composters ( were purchased from O2 Compost in Snohomish, WA. In addition, two Stall Sh*fters (R) were purchased from Brockwood Farm in Nashville, IN ( Eight barns participated in this initial phase, seven of which used the MicroBin system. The first compost micro-bin for this project was set up on May 18, 2011. The basic steps of this process are illustrated below.

  1. Assemble MicroBin on-site (A) and fill with manure and bedding (B).
    Turn on the blower to provide aeration (C) and monitor temperatures.
    After 30 days of composting, empty the bin (D) and sort the composted manure from the bedding using the Stall Sh*fter (E).
    Use the composted bedding in the stall (F) and composted manure in the garden (G).

Phase I Trial Sites

Snika Farms is a mid-sized boarding and training facility near Snohomish. The stalls are bedded generously with wood pellets, and we were able to recover about 50% of the compost as reusable bedding. In our assessment, this compost made very effective bedding when blended with fresh wood pellets. The moisture in the compost eliminated the need for additional water to make the wood pellets expand, while the wood pellets "brightened" the composted bedding in the stall. The manager did not like the dark color because the stalls were already dark (low lighting and dark paneling) and did not want to spend the extra effort managing a different type of bedding.

Paramount Equestrian is a large horse boarding and training facility near Arlington. This facility was recently sold, but at the time of this trial all stalls were bedded very heavily with wood shavings. By volume, over 80% of the stall waste was bedding and the remainder was manure. Through this project, we were able to show the farm owner how much bedding was being wasted because of stall management practices. He then worked with his employees to reduce the quantity of discarded bedding. Because of the high proportion of wood shavings, this compost made great bedding. It was still slightly damp after composting, but this reduced dust in the stall. The owner was happy to try it in a few of his stalls, but reported that clients often asked about the "dirty stalls." It was also difficult to convince him that the compost should be used in the stalls and not around his landscaping - it was a beautiful product!

Macomber Farm raises beef cattle and boards a few horses in Granite Falls. Their stalls are bedded conservatively with wood pellets, and they found the compost was too wet to be practical for bedding and used it for landscaping instead. Note how dark this compost is compared to the compost from Paramount Equestrian. This is due to the much higher ratio of manure to bedding, and wood pellets instead of wood shavings.

Top Fox Farms is a large boarding and training facility near Snohomish. Their composted bedding was also a great product (similar to Paramount Equestrian) and very practical for use in the stall. However, the manager felt it was too dark in color and looked "dirty." Before starting this project they had the manure regularly hauled off-site by a local shaving supply company. After participating in this project the owners became very proactive about composting and reducing their disposal costs. However, they could not make the leap to using the composted bedding in the stalls.

Mission Farrier School is located near Snohomish and operates a large boarding facility as well as a farrier school. The MFS is very conservative in their use of shavings, and this greatly reduced the re-use value of their compost. Although they appreciated the concept and supported the project, the composted bedding was too wet to be practical and the quantity recovered was very low, similar to Macomber Farm.

The Northwest Equine Stewardship Center (NWESC) is an equine rescue organization that works with Cedarbrook Veterinary Care (CVC) in the Monroe area. They are generous in their use of wood pellets for bedding (similar to Snika Farms). As a result, they recovered about 50% of the compost as reusable bedding. They found that the composted bedding was very effective when mixed 1:1 with wood pellets in the stall. The extra moisture in the compost eliminated the need to add water to the wood pellets and minimized dust in the stall. Dr. Hannah Muler of CVC noticed a distinct improvement in one of the rescue horses during this trial. The horse had recently received a tracheotomy and showed reduced skin and respiratory irritations while bedded with compost.

Rebecca Potter operates a mid-sized horse boarding facility and beds the stalls with wood pellets. After making one batch of composted bedding she found that the compost was too wet and was not practical as bedding.

The Leung Family keeps two horses at their home. They had previously designed and constructed a large aerated compost system for horse manure and were intrigued by this project. They borrowed the Stall Sh*fter to experiment with composted bedding on their own. While they appreciated the concept of recycled bedding, and that it was less dusty than wood pellets, they did not like how dark it was and felt that it was "more labor intensive than the positive outcome warranted."

Phase II: Imported compost

In June, 2012, we connected with a private company, Green Mountain Technologies (GMT), that designs and builds in-vessel composting systems on Bainbridge Island, WA. Completely independently of this Western SARE-funded project, they had also begun experimenting with compost as a stall bedding material. Their Earth Flow system uses a mechanical auger to break-up the manure and highly-controlled air flow to regulate temperature and moisture. This system allows for 100% resource recovery because there is no need to remove manure - it just gets incorporated into the final product. The result is very consistent and high quality bedding.

By delivering composted bedding (produced by the Earth Flow at Ios Ranch) directly to farms, we were able to increase the number of farms participating in the trial and eliminate variation between farms. At this point we were getting very curious about the possible health improvements reported in two separate barns in completely independent trials (NWESC and Ios Ranch). We sought out horses with hoof, skin or respiratory irritations with the intention of gaining more anecdotal evidence of the benefits of composted bedding.

Based on what we observed throughout the course of this project, the reported health improvements are likely due to one or more of the following factors:

1.The composted bedding is much less dusty, which can reduce respiratory irritations.
2.The composted bedding has a near a near neutral pH and, therefore, is less acidic than shavings or sawdust.
3.Compost has a thriving non-pathogenic microbial population that creates a very competitive environment. This is not conducive to fungal or bacterial skin and hoof infections such as scabs, rain rot or thrush.

While horse health is not the primary interest of the Snohomish Conservation District, nor the focus of this project, it is very important to horse owners. Highlighting the potential horse health benefits of composted bedding serves two purposes. First, it increases the interest in using composted bedding. Horse or barn owners who were not otherwise inclined to spend the time and effort to participate in a trial were willing to try compost with the hope that it would help horses with a skin or respiratory condition. And second, gathering sufficient anecdotal evidence about horse health would help justify a clinical trial. If a clinical trial were to show that composted bedding was beneficial, or at least not risky, it would contribute greatly to the acceptance of compost as a stall bedding material.

Phase II Trial Sites

Edensgate Farm is a small horse boarding facility in Monroe that beds stalls very conservatively with wood pellets. They used composted bedding in the stalls of several horses for about a month and showed positive results in terms of both stall management and horse health. In the words of Julie Boulter, owner and manager:

"I have had some interesting results from using the composted bedding. I am putting it in the general area where my horses tend to pee and poop anyway. It does a better job absorbing, even though my compost is really heavy at the moment from all the rain. Two of my three horses have become very specific about where they go in the stall when I use the compost and will ONLY go in that area when it is there. If I don't use it they tend to get messier again! The result is that (I think) I am using less bedding because I pretty much only need to remove the area where the compost is."

After three weeks of using the composted bedding, one horse showed a distinct improvement and the rain-rot scabs had started to go away:

After three weeks of using the composted bedding, one horse showed a distinct improvement and the rain-rot scabs had started to go away:

"Dolce is doing much better, probably 75% improvement. Aside from a stray scab or two, her back and belly is all cleared up. She still has two stubborn spots on either flank, but the scabs there are smaller now, and the area it covers is much less than when we started, so I am hopeful it will go away."

Holly Farm is a large boarding and training facility in Bothell, home to Equine Life Solutions. They used composted bedding (three parts wood pellets to one part compost) in one stall for seven days. They were happy with the compost and found they used less bedding because it was so absorbent. The composted bedding was used for a horse with a severe case of sweet-itch, and they did not notice any changes in his condition during this week. They look forward to continuing to experiment with composted bedding and use it in more stalls.

Liberty Bell Stables is a mid-sized horse boarding facility in Snohomish. They bed stalls with a moderate amount of wood shavings (less than Parmount Equestrian or Top Fox Farms). The owner used a composted bedding mixture for several weeks for her personal horse with a bad thrush infection in his hooves. She found that the 1:1 mixture worked well and did not affect the amount of time to clean the stall, the total amount of bedding used, or horse behavior. In her words, "He had thrush when I started and didn't when I stopped."

Lynn Gross owns several horses and keeps them at their home in Stanwood. At the time of this trial they were bedding stalls generously with wood pellets (similarly to NWESC). They used composted bedding for a week and had similar observations to many other participants. They found that it was harder to see the smaller pieces of manure and separate them from the bedding, and the dark color made it feel as if the stalls were not quite clean. There were not horse health concerns at the start of this trial, and no effects were observed. In her words: "If this product were used on the same farm it came from and the health of the animals was known, then I think this is a fabulous idea. The cost savings would likely be considerable."

Research results and discussion:
Lessons Learned
  1. Composted stall waste makes a soft absorbent bedding for horses or other livestock. There were no reports of increased stall odors or negative impacts on horse health caused by the composted bedding.
    Composted bedding is less dusty than shavings or wood pellets, darker in color and has a pleasant earthy odor.
    When separating the composted manure from the bedding, the amount and type of bedding determines the effectiveness of a bedding re-use system. Wood pellets are the bedding of choice when stall waste will be composted for use as soil amendment. However, their re-use value is limited because the ratio of bedding to manure is generally lower and the sawdust (from pellets) breaks down more quickly during composting. In general, farms using wood pellets recovered less composted bedding than farms using shavings. The bedding recovered was also darker and wetter. When using an in-vessel system like the Earth Flow, the ratio of bedding to manure does not have as much of an impact on the final quality of the bedding.
    Appearances are important. All of the barn managers we worked with were open to considering the value of composted bedding and appreciated the concept of recycled bedding and reduced disposal costs. However, it was a hard sell for most of their clients because it "looks dirty." The horse boarding and training industry in this region is very competitive, and many barn owners are unwilling to take any risks that might cause them to lose customers. In the future, work in this area would be most effective if it included outreach specifically targeted at the horse owners who board their animals at commercial facilities. Pressure from clients to improve waste management practices would have a lasting impact on the industry and help move it towards more sustainable waste management practices.
    Disease and parasite transfer are a concern for some people, but this does not seem to be as significant a concern as appearance. This is also more easily addressed through education about the compost process.
    Most participants reported that it was harder to see the wet spots when stalls were bedded with compost, and they felt that they used more bedding because they could not tell if it was dirty. It was our observation that when stall management practices were adjusted to account for the increased absorbency and biological activity of the compost, the damp bedding did not cause any problems and could be left in the stalls.
    The bedding re-use system that relies on the MicroBins and the Stall Sh*fter is too labor intensive to be practical beyond a pilot scale. We found that the bedding could be separated from about 1.5 cubic yards of compost in a little over an hour. Depending on the compost, this would yield about 0.75 to 1.2 cubic yards of bedding. This is not practical on a large scale and greatly limited the appeal of composted bedding for many of the trial participants. Because this was a pilot project, we did not have the capacity to establish a bedding compost system large enough to supply more than a few stalls at a time.
    Managing moisture was difficult and significantly limited the usefulness of the compost. The composted bedding ranged from about 40-70% moisture (estimated) between farms. Generally, farms using wood pellets were more conservative in their use of bedding and this, along with the smaller particle size, produced a compost that was too wet to use as bedding. Moisture challenges were also seasonal - compost produced during the summer months was drier.
    Even if the barn owners or managers were not ready to make the switch to composted bedding, this project helped us to start many conversations about manure management and resource conservation. This was a great opportunity to help horse owners make mental the leap from "waste" to "resource" through the various articles, presentations and farm visits.
Participation Summary

Research Outcomes

No research outcomes

Education and Outreach

Participation Summary:

Education and outreach methods and analyses:
Better Ground Website and Fact Sheet

Better Ground is the outreach program of the Snohomish Conservation District and includes a website and fact sheets on a variety of topics relating to resource conservation for farmers and homeowners. The Better Ground webpage dedicated to this project includes a brief overview of the project, a short video and links to articles ( Articles, social media activity, events and factsheets have all helped drive traffic to the Better Ground site throughout the course of this project. As of September 30th, 2013 the project web page had 516 page views. The video is also available on the Snohomish Conservation District YouTube channel. As of September 30th, 2013 the video had been viewed 1,683 times.

A two page Better Ground fact sheet, titled Horse Manure and Bedding: What Can I Do With It, is also available in print and online ( This fact sheet is also available on the King Conservation District website (

Snohomish Conservation District Newsletter

The Nexus is the quarterly newsletter published by SCD with a distribution of over 5,000 print copies and 1,600 digital subscriptions.

  • Using Compost as Horse Stall Bedding. The Nexus, Fall 2011.
    Horse Manure, From Waste to Resource. The Nexus, Spring 2012.
    Turning Horse Manure into Gold. The Nexus, Summer 2013.
Other Articles
  • Price, C. August, 2012. Composted Bedding for Horse Stalls. Northwest Rider Magazine. Newburg, OR. [NW Rider Magazine distributes 15,000 print copies monthly throughout OR, WA, ID, and CA and reaches 40,000 readers.]

    Price, C. February 27, 2013. Composted Bedding for Horse Stalls. Northwest Horse Source Blog. Accessed on: September 27th, 2013. [This posting received 1,423 views as of September 25, 2013.]

    Bogardus, M. and M. Brown. 2013. Benefits of Bedding Reuse for the Equine Industry. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013.

  • Washington Association of Conservation District Employees (WADE) Annual Meetings, June 2012 and 2013. Shared information about composted bedding and provided resources to for Farm Planner to share with landowners in their districts.
    Evergreen State Fair, Monroe WA. August 2012. Set-up MicroBin and Stall Sh*fter at two different locations at the fair. The bins were in place for 12 days and accompanied by photos and information about compost and composted bedding.
    The Country Living Expo - Washington State University Extension, January 2012. Worked with students from Stanwood High School to set-up and fill two MicroBins with stall waste from Paramount Equestrian one month prior to the Expo. This event was attended by over 1,500 people from around Washington State attending classes on a wide variety of topics related to farming, homesteading and country living.
Social Media

Links to the project website were made by the following organizations on Facebook (no. of "likes" or "friends" for each page):

  • Snohomish Conservation District (340)
    King Conservation District (392)
    Horses for Clean Water - Alayne Blickle (864)
    Cedarbrook Veterinary Care (671)
    Northwest Equine Stewardship Center (1,851)
    Sustainable Agriculture Research and Education (3,665)
    National Association of Conservation Districts (675)
    O2 Compost: On-site Composting Solutions (1,429)
    Mission Farrier School (1,043)
    NW Horse Forum (4,629)


  • Western SARE (@westernSARE) 249 followers) tweeted a link to the video on February 4, 2013 to 249 followers.
    SARE Program (@SAREProgram) retweeted the link from @westernSARE to 998 followers.

The Seattle Times Northwest Horse Forum (

  • Forum posting on October 25, 2011 received 226 views as of September 30th, 2013.
    Forum posting on September 25, 2013 received 36 views as of September 30th, 2013.

Education and Outreach Outcomes

Recommendations for education and outreach:

Areas needing additional study

This project demonstrated that compost is a safe and effective horse stall bedding. Future work should be focused in three areas:

  1. Developing systems for making composted bedding that are practical on a large scale and provide an economic incentive for large equine facilities to recycle their waste.
    Outreach and education programs directed at horse owners who board their animals at commercial facilities. If some horse owners are paying a premium to purchase "green" products for their homes (i.e. buying organic, natural or recycled products), would they also be willing to pay a premium to board their horses at facility that is managed in an environmentally sustainable manner? Pressure from horse owners boarding at commercial facilities would go a long ways towards lessening the environmental impact of the horse industry and increasing responsible manure management practices.
    Clinical trials to examine the effects of composted bedding on skin and respiratory conditions. There is currently strong interest among faculty at Cornell University, and University of Kentucky, as well as senior staff at the Maryland Department of the Environment. This research effort is being coordinated by Green Mountain Technologies, manufacturer of the Earth Flow compost system. A University-administered clinical trial could help legitimize the concept of composted bedding and increase acceptance by the general population.

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.