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How to Compost and Use Horse Manure

How to Compost and Use Horse Manure

If you have horses at your own place then you know how much manure and/or stall waste your horses can produce.  One horse can produce about 50 pounds of manure per day, over eight tons per year and if you use bedding/shavings, in no time you have a huge manure pile. 

 Some other concerns other then the amount of manure is ground contamination.  Because the composting process converts nitrogen into a less soluble form, it is less likely to be washed out of manure and into ground water and surface water.  Another concern is horses grazing near their own manure can be re-infested from larva from the worm eggs. There are also concerns regarding odor and fly problems. Composting horse manure is an excellent manure management technique, especially for the backyard or small acreage.   

 Here are just a few of the benefits of composting horse manure:

            -reduces the possibility of parasite re-infestation in your horse since the heat generated in the composting process kills worm eggs as well as pathogens and weed seeds.  

           -reduces flies by eliminating their breeding ground.

            -reduces odors since a properly managed compost pile should smell “earthy” and pleasant.

            -reduces the volume of material by about 50%

            -adding compost to soil builds good soil structure and texture, increasing the amount of air that can infiltrate and the amount of water it can hold. It can also loosen packed soil by opening up pore spaces that carry air and water down into the soil.  Compost can help hold water in loose sandy soil.  Adding compost can help control erosion.

            -adding compost supplies nutrients.  When fresh manure is spread on a field, about 50 percent of the nitrogen is in a highly soluble form and will be washed out by rain when it is spread on a pasture.  In compost, 95  to 97 percent of nitrogen has been converted to a much more stable from and will be slowly released, allowing plants to use it over a longer period of time.  Composted manure releases about 50 percent of its nutrients in the first season and a decreasing percentage in the following years. 

            -compost supports essential soil bacteria; feeds earthworms and allows them to multiply and gradually changes soil pH levels that are either too low (acidic) or too high (alkaline). 

Managing the Compost System

 It’s recommended to have 2-3 bins: the size of the bins will depend on the amount of manure you will want to compost. Each pile must be at least three feet high, otherwise the heat generated in the initial stages will quickly dissipate before the pile can reach high enough temperatures.  Composting will involve tarping, turning and watering.  Like most living things, the microorganisms that break down the manure and bedding are aerobic and require air and water.  Too much or too little of each can cause problems.

 Piling – To begin, pile the daily manure and stall waste in one bin. When that bin is full leave it and start filling the second bin and so on.  In 2-4 months the fist bin should be finished composting so you can start using the compost from that bin.

 Cover the bins – Covering your pile will allow you to regulate the amount of water and will speed up the process by not letting it get too wet or too dry.  Covering the pile will limit fly breeding and keeps the rain from washing nutrients out of the pile.  This can be done with a tarp, plastic sheet or a roof.  A cover will prevent your piles from becoming a soggy mess in wet weather and too dry in the hot summer sun.  Covering them also prevents the nutrients from being washed out into the surface water and causing problems.

 Aeration- Turning the manure and bedding allows oxygen to get to the bacteria and organisms so the break down in the material can begin.  This keeps the process aerobic and “earthy” smelling.  If the pile becomes anaerobic i.e. without air, it will have a foul odor. Air will filter down through the pile to a depth of only about 2 feet. How often you turn it will determine how quickly your manure will break down to a desirable dirt-like substance. If you don’t have access to a tractor or aren’t up to hand turning the pile, you can get air down into the pile by inserting PVC pipes into the center of the pile.  Before you insert the pipes, you’ll need to drill holes along the sides of the pipe so the air can reach deep inside the pile.  The pile will still need to be turned occasionally to get the manure that’s on the outside into the center so the heat from the process can kill parasites, weeds and weed seeds. 

  Temperature- Temperature is an important indicator of how well the manure pile is composting.  Most compost piles begin at a lower temperature range (about 50 degrees F – 110 degrees F)  then increase to the higher temperature range (110 degrees F – 160 degree F) and then gradually drop to ambient air temperature over a period of several weeks.   These high temperatures are necessary to speed up the rate of decomposition and to kill weed seeds and diseases.  At least several days of temperatures between 135degrees F and 150 degrees F are recommended.   You’ll want to watch the temperature to avoid overheating the pile since overheating stop the beneficial organisms needed for decomposition.  If your pile is overheating you can try reducing the size of your pile to bring the temperature back down to a desirable temperature.  The colder winter months will slow the composting process as the summer months will speed it up.

 Water- If there is too much water in the pile, there won’t be enough pore spaces for the air to flow through the pile. Too little moisture and the pile will dry out preventing the pile from heating up.  The compost pile should be about as damp as a wrung out sponge, not dripping wet. If you pick up a handful of material and it drips without being squeezed, it’s too wet.  If the material appears dry and crumbles after squeezing, it’s too dry.  If the material retains its clumped shaped after squeezing without releasing excess water and your hand is damp, then it’s just right for composting.  An easy way to add water is to water down the manure in the wheelbarrow before you dump it into the pile.

 Location- Choose a level site that will drain easily and is on fairly high ground so that the pile never sits in a pool of water. Also the site needs to be accessible with whatever equipment you will be using such as a tractor or a wheelbarrow. Plus the site needs to be close enough so you’ll be able to reach it with a hose so you can easily add water.  Choose a site that is somewhat close to the stall area so you don’t have to make numerous trips to dump the manure.

 The Finished Compost- The finished compost is a crumbly, evenly textured, earthy-smelling, dark material that looks like a commercial potting soil mixture. It will probably take about one to three months for each pile to compost during the summer and about three to six months in the winter.  If you monitor your piles with a thermometer (which can be purchased at a garden store or nursery) you’ll see a gradual drop in the higher “active” composting temperatures as it begins the curing process and composts into the finished material.   

 Using the Finished Compost- The easiest way to spread compost is to use a manure spreader but you can also spread it without a manure spreader.  You can load it in the back of a pickup and while one person drives another can shovel a layer of compost. 

Spread compost during the growing season when plants can use it and when it’s less likely to be washed away by the rain.  Apply approximately ¼ inch at a time and no more then three to four applications per year.  Re-apply only after the pervious layer has worked its way into the soil.

Compost can be used in the garden and landscape areas.  It can be worked into gardens by hand or with a tiller.  It can be added to the soil when planting trees, shrubs, annuals, or perennials.  Compost can also be used as mulch or topdressing around flowers, shrubs and trees which can help retain moisture during the hot summer. 

Troubleshooting

SYMPTOM                                                                             PROBLEM                                                                            SOLUTION

The compost has a bad odor.                                                    Not enough air.                                                        Turn the pile, add more PVC pipes.

The compost has a bad odor and is soggy                        Not enough air and/or too wet.                                 Mix in dry ingredients, add PVC pipes and cover

The inside of the pile is dry                                                       Not enough water                                                        Add water when turning the pile.

 The compost is damp and warm in middle but nowhere else.       Pile is too small                                                          Add more raw material.

The pile is damp and smells OK but is not heating up.        Too many shavings, or bedding, not enough manure.        Mix in nitrogen source (straight manure)