Story and photos by Ashley Daily
If there is one thing that horse owners have an ample supply of, it’s manure. Horses produce an average of 30 to 50 pounds of manure daily. Draft breeds will produce about double that amount, and miniature horses produce 10 to 20 pounds daily. When horses are stalled, owners can expect to remove as much as nine tons of manure a year. So what does one do with all that waste?
Removing manure from pastures is important in reducing the number of parasites that horses ingest, and manure can be valuable and useful stuff. The Helsinki International Horse Show in Finland uses a manure-to-energy technology developed by Fortum, an energy company. The 100 tons of manure produced during the horse show reportedly generated more than 150 megawatt hours of energy.
Although average horse owners aren’t likely to power their homes with manure, there is one very practical use for it — compost.
Methods of Composting
Known to some gardeners as “black gold,” horse manure contains several beneficial nutrients, including nitrogen — essential for growing leafy greens and garlic — as well as potassium and magnesium. Horse manure contains more nutrients than cow manure, including a higher nitrogen percentage at 0.7 percent, compared to 0.6 percent. However, fresh horse manure should not be used on gardens, especially vegetable gardens, because it can contain harmful pathogens and can burn plant roots.
Instead, manure should be composted before use because the heat generated by composting will kill any harmful bacteria, fly larvae, and weed seeds. To kill larvae, pathogens, and worm eggs, the pile should reach temperatures of 130 to 150 degrees for three to four days. A compost thermometer can show you how well the manure is “cooking.” It takes about three to six months for the composting process to be complete, depending on the size of the mound and how often it is turned.
The methods used in creating compost are “hot” and “cold.” In hot composting, conditions reach optimal moisture and temperature levels. The compost pile should be at least three to four feet high. Cold composting involves allowing bacteria to break down organic material naturally over time. That method is much slower than hot composting, sometimes taking as much as two years for the process to complete.
Hot composting is recommended for horse manure because it kills pathogens during the hot and cooling stages, whereas cold composting kills pathogens only during the cooling phase and doesn’t kill weed seeds.
Compost Bins
When starting your black-gold mine, choose a location that has good drainage and is away from water sources because runoff from the manure pile could contaminate the water. The pile should also be relatively close to barn and pens to make chores easier. It also needs to be in an area that is easily accessed by tractors so you can turn the manure over regularly — every two to three weeks is recommended.
Air is an important ingredient in creating compost because the bacteria and organisms responsible for breaking down the material need oxygen. Allowing the compost to aerate will also prevent it from having a bad smell.
Compost bins can be used if you want to keep the area looking neat. Bins can be built from cement or pressure-treated wood. Ideas for building compost bins can be found online, ranging from simple and practical to three-stall bins suitable for large equestrian facilities.
An Alternative Product
If you don’t have the space to create compost piles, you can still have the benefits of horse manure in your garden by brewing a tub of “manure tea.” This nutrient-rich organic fertilizer is easy to make. Simply fill a five-gallon bucket two-thirds full of water. Add enough manure to fill the bucket the rest of the way. Allow it to steep for one or two days, stirring once or twice a day. Once it is steeped, allow the solids to settle to the bottom of the bucket and then pour the liquid into a watering can or garden sprayer.
Manure tea can also be made by putting manure into a pillowcase, creating a teabag, and placing it in a bucket of water. This cuts out the need to separate the liquid. Before using the tea, dilute it with enough water to turn it a brownish yellow. Keep in mind that manure tea is high in nitrogen and shouldn’t be used on plants that require more potassium such as potatoes and carrots.
Benefits for Gardening
Composted manure has been shown to help gardens retain moisture longer and improve the health of plants, making them more resistant to disease. Research has shown that the benefits of manure to the soil can last as long as 10 years.
In the past, I never had much luck growing a vegetable patch. Lettuce seeds would sprout but never get big enough to harvest. Carrots would grow beautiful tops, but when they were pulled, they had only very small roots.
In spring 2024, I used a set of raised beds to try to grow vegetables. The beds were filled almost to the top with composted horse manure. A bag of commercial planting soil was used to fill them the rest of the way. When the plants matured, spinach and lettuce were growing enough to fill a salad spinner every time they were picked. Banana peppers continued to produce until the fall frost.
When planting flowers, I always plant them directly in compost-filled pots and containers, and they bloom beautifully throughout the season. Horse manure is excellent for growing roses because it contains essential nutrients to improve the overall health of all types of roses.
