How to use horse manure compost in 8 steps

I have had horses most of my life, but it was not until I first cared for a horse on my small acreage that it dawned on me, what should I do with all the manure? I am sure you, too, if you care for horses, have asked the same question at some point.

Horses produce 50 pounds of manure per day, over eight tons per year! Add to that the eight to ten gallons of urine a horse generates and the wheelbarrow or more of bedding used each day, and in no time at all, you will have a manure mountain.

All that takes up a whole lot of valuable space that you would probably enjoy using for more interesting things than stockpiling manure. For me, that first small acreage experience was over 30 years ago, but the process of working out a useful horse manure management option led me on the exciting journey I am on today as an environmental educator working with horse owners around the country.

In this article, I will share some of the problems associated with not having a solid system to deal with manure as part of your overall horse management program and cover the benefits of composting. We will go through the steps to manage compost and wind up with guidelines for using finished compost.

The trouble with horse manure

There are many concerns about the mismanaged manure pile (besides the obvious of wasted space and being an eyesore), such as:

• Horses grazing near their manure are quickly reinfested by larvae that hatch from worm eggs shed in manure.
• Odor and fly problems becoming a concern to you or your neighbors.
• Runoff from soggy manure piles causing water quality issues for creeks and wetlands, as well as for drinking water, which is a serious concern if you have your own well. Many areas have ordinances in place that strictly control these issues.

What is composting?

All organic matter, including manure and bedding, eventually decomposes. By providing an ideal environment, we put the beneficial bacteria, fungi, and other microorganisms that speed up the decomposition process to work.

As manure and stall waste are broken down, the microorganisms generate tremendous amounts of heat. This heat destroys weed seeds, fly larvae, worm eggs and other disease-causing pathogens.

Finished compost is crumbly, earthy-smelling, dark material and a marvelous soil amendment that holds in moisture and adds nutrients.

The compost bin vs. the compost pile

In order to compost and generate heat, it is important to stack your manure and stall waste a minimum of three to four feet high. (Aim to make it at least the size of a washing machine.)

You can build a bin out of cement or pressure-treated wood, or you can just create a large manure pile. Larger horse facilities or those with tractors might need a sturdy bin design with strong walls. If you live in a wet climate, you will need either a roof or a tarp over your bin to avoid piles getting too wet and soggy. A cement pad for the bottom is helpful when using a tractor to keep the area from turning muddy in the winter or rainy season.

How to manage composting systems 

This includes tarping (covering), turning or aerating, and watering. Like most living things, the microorganisms that break down manure and bedding are aerobic, requiring air and water. Too much or too little of either can cause problems. Some simple steps to follow to manage the process are:

1. Choose the right location. Begin by locating an appropriate place for your composting site. For chore efficiency, choose an area convenient for chores with easy access to your horses, barn and paddocks. This area should be high, well-drained and away from waterways. Locating your pile at the bottom of a hill or in a wet area may mean it turns into a pile of mush. A dry, level area is especially important when it comes to accessing the pile with any kind of heavy equipment, such as a tractor or truck (which you may want for spreading the finished compost).

2. Piling. Place daily manure and stall waste in one bin or pile. When that bin or pile is as large as you want it (at least three feet), leave it and begin building a second pile or bin, and so on for the last bin. In two to four months, the first bin or pile should be finished, and you can start using the compost from that bin. It is a good idea to have two or three separate piles — or more if you would like.

3. Keep it covered! Covering your compost prevents the valuable nutrients you are saving in the compost from getting washed out and causing problems with the neighbors or in nearby waterways. A cover keeps your piles from becoming a soggy mess in the winter or too dried out in the summer. This can be accomplished with a tarp, plastic sheet or by building a roof.

Since you will need to pull the tarp back every time you clean your horse’s stall and paddock, make the tarp as chore-efficient and easy to use as possible. You may want to attach your tarp to the back of your compost bin. TIP: If you live in a windy area, weigh down your tarp with milk jugs full of gravel.

4. Get air into the pile. Turning the compost-to-be allows oxygen to get to the bacteria and organisms that break down the material into dirt-like organic matter. This keeps the process aerobic and earthy smelling. If the compost becomes anaerobic, without air, it will have a foul, undesirable odor.

How often you turn it determines how quickly your compost will be ready. On its own, air will permeate into the pile to a depth of one to two feet, so it’s the center of the pile that really needs air. Unless you have access to a tractor or enjoy a good workout, turning the pile by hand is difficult.

An easy way to get air to the center and avoid frequent hand-turning is to insert a couple of five- or six-foot PVC pipes into the center of the pile like chimneys. Buy PVC pipes with holes in them or use a drill to put in holes along pipes. Alternately, you could use a tamping rod to insert a few holes into the center.

The pile will still need to be turned from time to time to get the manure on the outside into the center so heat from the composting process can kill pathogens and evenly break down the material.

5. Keep it damp. Your compost material should be about as damp as a wrung-out sponge. Particularly in the summer, you will need to find a way to water your compost. Either use a garden hose when you turn it or just hose down the manure in your wheelbarrow before you dump it into the pile.

The compost should be damp but not dripping with water. If you squeeze a handful of it in your hand (wear a glove if you want), you should only be able to squeeze out a drop or two.

6. Optional: Monitor the heat. A wonderful component of composting is the heat generated by the beneficial microbes. A compost pile can get fairly warm, about 130–150°F. If you want the compost to kill fly larvae, worm eggs, weed seeds and pathogens, you need it to reach these temperatures for about three or four days. You can monitor the temperatures easily with the aid of a long-stemmed compost thermometer purchased at a local garden store.

7. Finished compost. How actively you monitor the air and water and how often you turn it determines how quickly it will compost. It should take around three to four months to finish, perhaps longer in the winter. The volume of material piled up will decrease in size by about 50%. You will know when your compost is ready when the material looks evenly textured, dark and crumbly like dirt and no longer like the original material. It should be 90°F or less.

8. Put that black gold to good work! Compost is a rich soil amendment that improves the health of both plants and soil and helps to retain moisture. You can use your compost in your garden, give it away to your neighbors, or spread it on your pastures. Spreading manure in pastures during the growing season — from late spring to early fall — is best.

You can use a manure spreader or simply spread it with a shovel from the back of a pickup truck or by the bucketful with a tractor. Do not spread it too thick to avoid smothering grass; just a sprinkling of about 0.25–0.5 inches at a time and no more than three to four inches per season in the same area.

In conclusion

Finished compost is a precious soil amendment infused with micro and macronutrients that work to add nutrients in a time-release fashion. Compost adds “life” to soils in terms of beneficial bacteria and fungi. Academic research shows that compost makes plants healthier, more disease-resistant and that just one application of compost can have benefits lasting five or more years.

Compost will also help hold in moisture — very important for helping your pasture survive a summer drought or climate change! And composting provides you with a free, easy source of compost that saves you money. Your horseless gardening neighbors may find it a valuable commodity as well!

For questions or design help, contact Horses for Clean Water, your local conservation district or the Natural Resources Conservation Service.  

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