How to Compost and Use Horse Manure
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By Alayne Blickle, King Conservation District

Introduction

If you care for horses on your own place, you have, no doubt, wondered about what to do with that huge mound of manure and stall waste generated by your horse. In fact, one horse can create a serious pile in no time -- one horse produces about 50 pounds of manure per day, over eight tons per year. Add to that the wheelbarrow or more of bedding you use each day and in no time at all you have a virtual manure mountain!

There are other concerns for the mismanaged manure pile as well -- horses allowed to graze near their own manure are quickly reinvested by larva which hatch from the worm eggs. Runoff from soggy manure piles can cause serious surface water contamination problems, and in some parts of the country these issues are strictly controlled by laws. Then there are the associated odor and fly problems, and if you live close to others this may concern your neighbors as well.

Composting horse manure is an excellent manure management technique, especially useful for backyard or small farm owners. Larger horse facilities can also develop a composting system, but they may wish to get some additional design help from their local Conservation District, USDA Natural Resources Conservation Service or Cooperative Extension (see "For More Information").

Picking up manure from stalls, paddocks and confinement areas on a daily or regular basis and composting it has several benefits:

  • it reduces the possibility of parasite reinfestation in your horse -- the heat generated in the composting process kills won-n eggs as well as pathogens and weed seeds
  • it reduces flies by eliminating their breeding ground o it reduces odors
  • it reduces the volume of material you have piled up -- the composting process will reduce the size of the pile by about 50%
  • it reduces the chance of manure contaminated runoff from your property reaching surface or ground waters in your area
  • it provides you with a free, easy source of compost -- a valuable addition to your pastures, garden, yard or horseless neighbors
  • it makes your property more pleasing for you and your neighbors to look at and enjoy


This article will provide information on how to build and use a horse manure composting system for horse owners with 1 to 5 horses. Simple tools like a wheelbarrow, manure fork and shovel are all you will need to manage it. Bins made of landscape timber (or a similar wood) are used to store the manure and stall waste, and allow for composting. The bins not only look nice, but they make the whole process more manageable and organized.

You can tailor your composting system to meet your needs depending on how many horses you have, the amount and type of bedding material you use, and how you plan to use the finished compost. If you have a larger horse farm and plan to use heavy equipment, like a tractor, you will need a sturdier design, such as one made from concrete (see "For More Information").

Planning Your Composting System

First, select a site for your compost system. Look for a high, level area on your property -- don't put your compost bins in a low lying area or it will turn into a soggy mess. A location that's convenient to your stall and paddock areas will make your manure management process more "chore efficient" and less time consuming. Also, consider what you are going to do with the finished compost -- if you plan to give it away you may want to locate your compost bins along the driveway or near a road. If locating your bin is a problem due to serious mud or drainage issues during your winters get additional help from your Conservation District, USDA Natural Resources Conservation Service or Cooperative Extension (see "For More Information").

Next, decide on the number of bins needed. The bins go next to one another so they share a common side. Having three bins is probably the most useful and will allow for more flexibility. For one or two horses you can do fine with just two bins. The system works by piling the daily manure and stall waste in one bin. When that bin is full you leave it, allow it to compost and start filling the second bin. Once the first bin is done composting (more about finished compost in a moment) you can start using it. When you have three bins you can have one bin where the daily waste is piled, another bin which is full and in the composting stage, and a third bin for where the finished compost can be taken out and used at your convenience.

Determine your building materials. The bins shown in this article are made from cherry landscape timbers, sometimes called peeler logs. These are used because they are the least expensive in the author's part of the country (the Northwest), but you can use any kind of boards or materials you have available. Using timbers or boards versus sheets of plywood works better because you can easily replace the individual boards or timbers over time as they deteriorate. They will also allow for air to permeate into the pile along the sides if you keep a 1/2" space between them as you build the sides. Using treated or untreated wood will work, however untreated boards will last longer with a coat of exterior-type paint. There may be other materials available in your part of the country which are low cost or even free that you could use for this purpose. Think creatively -- you may be able to recycle and reuse

Building Your Compost Bins

After you have decided where to put your compost system and how many bins you want, it's time to purchase materials and put your bins together. Each bin will cost about $ 100 depending on the materials you use. Three bins can be built by one person in a weekend. A list of materials and tools needed, as well as the design, is included at the end of this article.

1. Layout

Assemble all the tools and materials. Using the landscape timbers, outline the exact location of your bins. Be sure the side walls attach to the back wall the same way on each side and that the side walls are parallel to each other (see diagram).

2. Post Holes

Locate the holes for the vertical supports by measuring in two feet from each end. Dig the holes for the supports two to three feet deep. Place each support in a hole and back fill with about 1/3 of the dirt. Use the level to make sure the support is vertical and pack the dirt around the support with the tamping rod. Continue filling, tamping and checking level of the support until the hole is completely filled and the support feels firm in the ground. (The trick to getting a firm support is using a small amount of dirt and tamping, then adding more dirt and tamping some more). Do this for all the supports.

3. Sides

Place the first board on the ground flush against the two supports of the back wall. Use the level make sure the board is horizontal. Drill a 1/4 inch hole through the horizontal board into each support, being sure to maintain the level. Secure the board to each support with a lag screw. Continue attaching the boards until you reach the desired height, then go on to the other sides.

4. Additional Bins

If you are building a two or three bin system, build the remaining bins in the same fashion attaching to the first bin using one of the existing sides.

5. Customizing

An addition you may wish to make to your composting bin is a way to close off the front as your bin gets full. You can do this by simply nailing boards across the front as you go along or you can build a "channel" on the front, inside of each side wall. This channel will allow you to slide in eight foot 2"x 8" boards as your bin fills up. There may be other ways that you can "customize" your compost bin system to meet your needs -- maybe paint it to match your barn or neighborhood or build, a roof over it.

Managing the Compost Process

Those familiar with garden composting already know that compost management activities include covering, turning, and watering. Like all living things, the micro-organisms which break down the manure and bedding require air and water. Too much or too little of each can cause problems. Let' s look at ways to regulate the amount of air and water in your manure composting bins.

Covering your bins is perhaps the single most important aspect to composting! You can either build a roof or simply use a tarp or a sheet of plastic. The cover controls moisture -- it prevents your manure piles from becoming soggy in the winter or dried out in the summer. Covering them also prevents the nutrients you're trying to save for your pasture or garden from being washed out into the surface waters and causing problems.

Turning the compost-to-be allows oxygen to get to the bacteria and organisms which break down the manure into soil-like structures. How often the pile is turned determines how quickly the compost will be ready. However, unless you have access to a small tractor or enjoy a good work-out, turning a pile of this size can be difficult. An added benefit for building the bins with landscape timbers is that because of the octagonal, uneven shape of the timbers, you end up with "slots" between the timbers. These spaces allow for air to pass through the sides. Air will permeate through the pile to a depth of about three feet. Beyond that, an easy way to get air to the center and avoid turning the pile is to insert a couple of two inch PVC pipes into the center of the pile like chimneys. Use a drill to put holes in the sides of the pipes before you insert them. The pile will still need to be turned occasionally to get the manure on the outside into the center so the heat from the composting process can kill parasites and seeds. Another advantage to the pipes is they can be used to prop up the tarp a bit and allow air to circulate across the top of the pile.

Keep the manure pile about as damp as a rung-out sponge. In the summer you will need to water the pile. There are different techniques for watering and you may want to try your own, however the easiest method may be to simply water down each wheelbarrow load before you dump it into the bin. Other possibilities include watering the pile with a garden hose when you turn it or use the pipes to get water into the center to the pile. But be sure not to let it get too dried out or the composting process will stop and may be difficult to restart!

It is fine to add garden waste and lawn clippings to your compost system. However, don't let grass clippings clump together -- spread clippings out so air can permeate through them. Kitchen scrapes are best managed in a worm bin so that you don't end up attracting rats or other unwanted pests to your horse area. Also, only use herbivore manure in your composting system. Carnivores, such as our household dogs and cats, may share similar pathogens with us and their manure needs to be handled and treated differently.

Your compost system should smell "earthy" and not unpleasant. Odors and flies are associated with fresh manure and once part of the composting process there shouldn't be a problem. If it is not heating if it has a bad odor it means something is not being managed properly -- check to be sure it is not too wet or too dry.

The Finished Compost

Depending how often you turn 't and whether it stays damp, your compost could be ready in as soon as a month. Most likely, it will take a couple months in the summer and three to five months in the winter when temperatures slow down the microbial activity,. You will know your compost is ready when it has reduced in volume about 50% and the material looks evenly textured and crumbly like soil and no longer like the original material.

Compost is a rich soil enhancement which improves the health of both plants and soil. Compost improves the physical structure of soil, adds fertility and increases the ability of soil to hold moisture and plant nutrients. It can be added to your pastures, gardens, flower beds, or even used in house plant potting soil. Spread it in a thin layer on your lawn or use it as a mulch to control weeds and retain moisture in the garden, flower areas or shrubs. You may even have a good supply of horseless neighbors who would love to have some composted horse manure for their gardens or flower beds.

Be sure to spread compost on pastures only during the growing season -- late spring, summer and early fall. If you apply it when plants aren't growing you run the risk of having the compost and nutrients washed off the field and possibly into the surface or ground water. Spread a 1/2 inch layer at a time, totaling about three to four inches per year. You can spread the compost either by hand with a shovel or with the aid of a manure spreader pulled by a lawn tractor or small pick-up.

If you're so inclined, composting is a very useful manure management technique. Whether you have a pasture, garden, flower bed, or lawn composting your horse's manure and stall waste creates a beneficial, free product you can use. Returning the nutrients and organic materials back into nature's cycle changes a potential liability into an asset. Try it and find out how easily compost happens!

For two 4'x8'x8'bins, the following list of equipment and supplies are needed:

SUPPLIES
70 - 8' landscape timbers (or similar Wood)
140 - 5/16" x 5 1/2" lag screws plastic sheet or tarp to cover top

EQUIPMENT
post hole digger drill & bit (1/4" - 5" long) ratchet & socket set carpenter's level, power or hand saw tamping rod or similar tool

NOTE: number of timbers and lag screws will depend on the width of the timbers you purchase and how tall you wish to make your bins.


FOR MORE INFORMATION ON COMPOSTING HORSE MANURE

Natural Resource Conservation Service works with farmers and ranchers on issues relating to wise use of the natural resources, such as pasture, manure and mud management. You can find the number for your NRCS office listed in the phone book under federal government, US Department of Agriculture, Natural Resource Conservation Service. In King County you can reach the NRCS at 206-764-3325.

Conservation Districts also work with farmers and livestock owners, often for smaller, noncommercial places on similar land management practices. You can contact your local Conservation District by calling the NRCS office. The NRCS will be able to tell you the name. location and phone number of your Conservation District, If you live in King County, you can call the King Conservation District at 425-226-4867.

Cooperative Extension -- contact your county cooperative extension office to get more information on pasture and manure management for horses, as well as composting. They can be located in the phone book under your state land-grant university (if you have trouble locating them ask for help from your public library's reference librarian). In King County you can reach WSU King County Cooperative Extension at 206-296-3900.

Your county solid waste department may also be able to help you with more information on composting or other ideas for manure management. Many counties (or city solid waste department) offer Master Composter classes which, although geared towards the back-yard gardening-type composter, will certainly provide you with more information and understanding on the compost process. The King County Solid Waste Compost Hotline is 206-296-4466.

Many books are available in the library on composting. A good source for information on agricultural composting is the On-Farm Composting Handbook, distributed by Northeast Regional Agricultural Engineering Service, 152 Riley-Robb Hall, Cooperative Extension, Ithaca, NY, 14853-5701. Phone (607) 255-7654 or FAX (607) 255-4080, or email at NRAES @corrnell.edu.

TROUBLESHOOTING THE COMPOST PROCESS
Symptom Problem Solution
Compost has bad odor Not enough air Turn pile, add (more PVC pipes).
Compost had bad odor and is soggy Not enough air and too wet Mix in dry ingredients like straw and shavings, add (more) PVC pipes, cover with a tarp.
Inside of pile is dry Not enough water Add water when turning pile or adding materials to pile.
Compost is damp and warm in the middle but nowhere else Pile is too small Collect more raw material and mix into old ingredients. Piles small than 3' square have trouble holding heat.
Pile is damp and smells fine but is not heating up Too many shavings, wood chips, or bedding and not enough "food" for bacteria Mix in a nitrogen source - manure, fresh grass clippings, blood meal, or ammonium sulfate.

Pierce Conservation District
5430 66th Avenue East
P.O. Box 1057
Puyallup, WA 98371
Phone: (253) 845-9770

Fax: (253) 845-4569
Toll Free: (866) 845-9485
E-mail: info@piercecountycd.org