How to Compost Horse Manure

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Composting is an easy, effective way to manage manure on your small-acreage horse farm. You can add your food and yard scraps to your compost bin as well, reducing your garbage bill (which means more money to spend on your horses!)

It is also a resource that you can sell to further fund your horse habit if, like me, you live in the desert and don’t have a garden. If you wish to use it yourself, compost improves your pastures or the condition of your garden soil.
 
You can purchase a pre-made compost bin, but they are often too small for the manure quantities that horses produce. You can easily build an eight-foot square compost bin from pallets. With two horses on my property, I filled this bin in five months, so this is a very practical size for small-acreage farms. You can read the full instructions here.
 
Now you’ve built your bin, but composting is more than just piling your manure and covering it up. Follow these steps to produce amazing, rich compost.
 
Moisture
 
Moisture is an important component of compost. Horse manure naturally dries as it ages, so you will need to add moisture to your compost pile so that it reaches the ideal 40 to 65 percent moisture content.
 
You can accomplish this in two ways: you can add moisture to manure before you dump it in your compost bin, or you can add water directly to the bin. I add my water directly to the bin because I have a water spigot close by. I spray my pile and then use my compost turner to work the moisture down to the lower layers. If your pile is not near a spigot, park your manure cart next to a faucet and wet your manure to the correct moisture level before you dump it. The effect is the same either way.
 
Give your compost the “wet rag” test to see if you have the correct moisture content. Pick up a handful and squeeze. It should feel damp but not soaked, and a few drops should squeeze out.

Heat
 
Your compost pile needs to be between 140 and 160 degrees Fahrenheit to properly grow good microbes and kill pathogens. Some compost piles will reach temperatures over 180 degrees Fahrenheit, which increases the risk of spontaneous combustion. This means that monitoring your compost pile’s temperature is essential.
 
The easiest way to monitor temperature is with a compost thermometer. I use and recommend Cate's Garden Compost Thermometer (buy it here). I check the temperature once a day, during the heat of the day, but you can check less often. A good time is right before you turn your compost pile every five days. This will let you know if your pile is getting too hot and if you should turn your pile more often.
 
I keep my compost pile covered to prevent weeds from blowing in and to keep the temperature in range. I use this basic blue plastic tarp by Grizzly Tarps (buy it here) but I live in an area with low wind speeds. If you live in a breezy part of the country, spend the money and invest in a canvas tarp. I used this Cartman Tarp in Montana and it lasted me for five years (buy it here).
 
If your compost pile temperature is over 160 degrees, you need to turn it to redistribute the heat. The easiest way to do this is with a compost aerator. I use and recommend the basic Yard Butler Compost Aerator (buy it here).

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Carbon to Nitrogen Ratio
 
Creating compost is a science, and you need to get your carbon to nitrogen ratio correct for the proper breakdown. Ideally, your compost pile should have 25 to 30 parts of carbon to 1 part of nitrogen. If your carbon ratio is too high, the breakdown will be very slow. If your carbon ratio is too low, your pile will have a foul odor.
 
Manure has a natural carbon to nitrogen ratio of 15:1, so the best way to achieve the ideal compost mix is by adding other elements to your pile. “Browns” are higher in carbon, while “greens” are higher in nitrogen. If your pile is primarily manure, you need to add more “browns.”
 
Browns:

•    Wood Ashes 25:1
•    Shredded Cardboard 350:1
•    Shredded Newspaper 175:1
•    Corn Stalks 75:1
•    Fruit Scraps 35:1 (avoid citrus peels because the acid will kill microbes)
•    Leaves 60:1
•    Peanut Shells 35:1
•    Pine Needles 80:1
•    Sawdust 325:1
•    Straw 75:1
•    Wood Chips 400:1
 
Greens:

•    Alfalfa 12:1
•    Bermuda Grass Hay 25:1
•    Clover 23:1
•    Coffee Grounds 20:1
•    Grass Clippings 20:1
•    Vegetable Scraps 25:1 (avoid onions because they kill microbes)
•    Weeds 30:1

Turning Your Pile
 
The microbes in your compost pile need an aerobic environment – one rich in oxygen. Your pile can become stagnant and create anaerobic pockets where microbes die. To prevent this, you need to regularly turn your pile.
 
I use a Yard Butler Compost Aerator (buy it here) but you can also use a metal pitchfork. Insert it into your pile and turn to create air pockets, mixing new manure in with the old. You should do this every five days, or more often if your temperature is rising above 160 degrees or develops a foul smell. Be sure to replace your cover after you turn your compost to raise the heat.

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Items to Avoid
 
Compost piles are only for biodegradable, plant-based items. These items should NEVER go in your compost pile:

•    Charcoal Ashes
•    Cat Litter
•    Colored Paper
•    Lime
•    Meat or animal by-products (grease, fat, oil, bones)
•    Plastics
•    Citrus Peel
•    Onions
•    PLU Stickers on Produce
•    Sawdust or wood chips from treated wood
•    Large branches
•    Synthetic fertilizer (like Miracle Grow)
 
Black Gold
 
With horse properties becoming smaller and smaller and counties enforcing more regulations on manure management, composting is a realistic option for horse owners.  You can spread this valuable resource on your pastures to improve your grass, use it in your garden, or sell it for extra money to fund your horse habit. Composting requires only a little effort on your part and has a great positive impact on the earth. Take a little time to compost your manure and it will pay off for you over and over.