Composting

A horse generates roughly fifteen to twenty tons of manure per year. That's a lot of waste you have to do something with. You can haul it away, you can spread it on pasture, you can leave it in a pile and deal with it later, or you can compost it into a valuable soil amendment. Composting is the option most people don't think about but should, because it solves the problem of what to do with all that manure while creating something actually useful. A good compost pile turns manure from a waste management problem into a resource that improves your soil, provides free fertilizer, and reduces the volume of material you're managing.

Most horse owners pile manure somewhere because it's the simplest immediate option. You clean stalls or paddocks, you move the manure to a pile, and you deal with it eventually. Eventually comes years later, if at all. Manure piles attract flies, smell bad, and do nothing productive. They're a management liability and a potential health issue. They're also wasted potential. That manure could be building soil on your land instead of piling up and drawing insects.

Composting works because it's a biological process. Manure plus bedding equals carbon and nitrogen. Add the right conditions—moisture, aeration, heat—and you get decomposition. Microorganisms work through the pile, generating heat that kills pathogens and weed seeds and breaks down the material into finished compost. What started as a pile of manure and bedding becomes a dark, crumbly, soil-like material that improves soil structure, adds nutrients, and increases water retention. This finished compost is valuable for improving pastures, growing hay, growing vegetables, or giving away to friends who want it.

Composting isn't complicated or expensive. You don't need fancy equipment. You need a location for your pile, material to compost, and a basic understanding of what makes composting work. A simple manure pile can compost if you manage it right. A sophisticated bin system works too. Both approaches can produce finished compost, and both start with understanding what composting requires and what mistakes cause problems.

This guide walks you through starting a compost pile, maintaining it so it actually decomposes, using finished compost on your property, and managing the whole system so it actually solves your manure problem instead of just moving it somewhere else. You'll learn why some piles compost beautifully and others just sit there for years, and what you can control to make your pile work effectively.

The simplest compost system is an open pile on the ground. You choose a location, you pile manure and bedding in one spot, and you manage it by adding material periodically and turning or aerating it. Open piles work, they're free beyond the location, and they can produce finished compost if you manage them well. The downside is that open piles tend to look bad, smell bad if they're not managed right, and don't compost as quickly or efficiently as contained systems. But for someone with land and a willingness to manage an open pile, it's a perfectly functional approach.

A step up from a bare pile is creating a contained compost area using simple fencing or a bin structure. You can build a bin from wooden pallets wired together, creating a contained space where manure piles up inside a frame. You can build a more permanent structure from wood or cinder blocks. You can buy a manufactured compost bin. The advantage of contained systems is that they look neater, they manage smell better, they keep rodents and flies more contained, and they make it easier to turn the pile if you're turning it. The disadvantage is the small investment in building or buying the bin.

For serious horse owners, a three-bin system works beautifully. One bin is where you actively add new manure and bedding. As that bin fills, you start adding material to the second bin. Once the first bin is full and the second has some material, you start turning the first bin—aerating and mixing it. The third bin is where you age finished or nearly-finished compost before using it. This system keeps material organized, makes turning easier, and lets you have compost in various stages of decomposition simultaneously. You can make a three-bin system from pallets for minimal cost.

Bedding choices affect how quickly your compost pile works. Shavings compost fine and are the most common bedding. Straw bedding decomposes but leaves straw fibers longer than shavings do. Sawdust is very fine and compacts, which can slow composting if you have too much of it. Pine shavings smell better than other shavings but pine resin can slow decomposition slightly. The bedding you use is usually whatever your facility uses or whatever you buy, so adapt your composting approach to your bedding rather than changing bedding to compost better.

Manure-only compost is an option if you're not using bedding in your paddocks or if you want to separate manure from bedding. You can compost just the manure without bedding, which decomposes faster than manure-plus-bedding because there's more nitrogen and less carbon. But manure alone can get compacted and anaerobic, which slows decomposition. Most people find that composting manure-plus-bedding together works better and actually uses all your waste stream rather than leaving bedding somewhere else.

Location matters for your compost system. You want a location that's out of the way but convenient enough that you're actually willing to move manure there regularly. You want decent drainage so water doesn't pool around your pile. You want a spot that's relatively flat and stable. You don't want your compost pile immediately next to your house or a neighbor's house if flies and smell are concerns. A location that's visible from your barn or paddock is good because you're more likely to manage it if you see it regularly. A location that's screened from view is good if you have neighbors who care about aesthetics.

Successful composting requires understanding what the pile needs to decompose properly. Composting is a biological process—microorganisms break down the material, and they need certain conditions to work. The main things they need are carbon, nitrogen, moisture, and oxygen. Your manure and bedding provide carbon and nitrogen. Moisture comes from the manure and the weather. Oxygen comes from the pile being porous and from turning or aerating it. Without adequate oxygen, your pile becomes anaerobic and smells terrible while decomposing very slowly. With adequate oxygen, decomposition happens relatively quickly and smells much better.

Carbon-to-nitrogen ratio affects how fast your pile decomposes. A rough target is around twenty to thirty parts carbon to one part nitrogen. Manure is nitrogen-rich, bedding is carbon-rich. The combination of manure and bedding usually gets you into a reasonable carbon-to-nitrogen ratio naturally. If you're composting just manure without much bedding, decomposition is slower because you need more carbon. If you have excess shavings without manure, you can compost them but decomposition is very slow because there's not enough nitrogen to fuel the process.

Moisture needs to be moderate. A compost pile that's too dry decomposes very slowly. A pile that's too wet becomes compacted and anaerobic. The right moisture level is roughly like a wrung-out sponge—if you squeeze it, a little water comes out but it's not soggy. In dry climates or during dry seasons, you might need to add water to your pile to maintain the right moisture. In wet climates, you might need to provide some kind of cover to prevent the pile from getting waterlogged. Most people don't need to do much moisture management—the natural moisture in manure and rainfall usually keep things in the right range.

Aeration is critical for fast composting. When you turn your pile, you're introducing oxygen and mixing the material so all of it gets exposed to microbial activity. A pile that's turned regularly will compost in several months. A pile that's never turned will compost eventually, but it takes a year or more. If you're willing to turn your pile, you get finished compost much faster. If you're not willing to turn it, you need to accept that it'll take a long time. Some people use a tractor with a front-end loader to turn their piles. Some turn piles by hand. Some build piles loosely enough that they naturally aerate. Whatever approach you use, aeration speeds decomposition.

Temperature affects decomposition speed. Hot compost piles—piles that are actively decomposing with internal temperatures reaching 130 to 150 degrees—compost very quickly and the heat kills pathogens and weed seeds. A properly managed manure compost pile gets hot almost immediately due to the nitrogen content of horse manure. Cold piles decompose much more slowly. The difference between a hot pile that's being turned and a cold pile that's sitting in a pile can be several months of decomposition time.

Finished compost looks dark and crumbly, almost like soil. It doesn't have a strong manure smell—it smells earthy. The material is broken down enough that you can't identify the original bedding or manure. If your pile still looks like manure and shavings, it's not finished yet. You can use partially finished compost on pastures or hay fields—the material will continue decomposing in place. But for using compost on vegetables or in gardens, you want it fully finished.

Hot compost piles can actually generate enough heat to be a fire risk if they dry out and are in the wrong location. This is rare, but it's why you don't want a compost pile right next to a barn or wooden structures. A properly managed pile with adequate moisture isn't a fire risk. But an abandoned pile that's dried out in extreme heat in the middle of summer could theoretically spontaneously combust. This isn't a reason not to compost. It's just a reason to manage your pile reasonably and not put it immediately next to flammable structures.

Pathogens in manure are a consideration if you're using compost around food crops or areas where kids play. Hot composting—piles that reach temperatures of 130 to 150 degrees—kills most pathogens including many parasites. However, horse manure can contain parasites that are resistant to heat, so if you're composting manure from horses with parasite issues, don't use that compost around vegetable gardens where it might contact food crops. Use it on pastures or ornamental areas instead. If you're concerned about pathogen kill, let your compost age for at least six months to a year before using it anywhere food might be grown.

Weed seeds are present in horse manure if the horses have been eating hay or pasture with mature weeds. Hot composting kills many weed seeds, but not all of them, especially if your pile doesn't get hot enough or doesn't stay hot long enough. If you're spreading compost on pastures, you might be spreading weed seeds. This is usually not a major problem—weeds come from many sources and compost is just one of them. But be aware that using fresh or partially decomposed manure can introduce weeds. Using finished, well-aged compost reduces this risk.

Fly management is one of the most common complaints about manure piles. A pile that's covered, contained, or actively being turned regularly has fewer fly problems than a bare pile that's sitting undisturbed. If you're piling manure without composting it, you'll have more flies than if you're actively composting. One approach to reducing flies is adding agricultural lime to manure as it's being piled, which helps with odor and fly management. Another is covering your compost pile or keeping it in a contained bin where flies can't lay eggs. Regular turning also reduces flies because the activity and heat discourage them.

Rodents are attracted to compost piles, especially if there's grain in the manure or if food scraps are being added. Horse manure alone doesn't attract rodents much, but if you're adding kitchen scraps or grain spills to your pile, you're creating a rodent attractant. If rodents are a concern, don't add grain or food scraps to your horse manure compost. Keep your pile contained and managed rather than just a big pile on the ground where rodents can burrow into it.

Maintaining your compost pile is straightforward. First, consistently add material to it. As you clean stalls or paddocks, move the manure and bedding to your pile. If you're using a bin system, keep filling until the bin is full. Then start the next bin. You'll naturally rotate through your bins if you have multiple ones. The key is consistency—regular material going into the pile keeps it active and decomposing.

Second, manage moisture if your climate requires it. In wet climates, consider putting a simple roof or tarp over your pile to prevent it from becoming waterlogged. In dry climates, periodically add water if the pile is drying out. This maintenance is usually minimal—most piles maintain the right moisture naturally from manure moisture and rainfall.

Third, turn your pile if you're willing to put in the effort. Turning can happen weekly, monthly, or less frequently depending on how fast you want your compost. The more often you turn, the faster it decomposes. The less often you turn, the longer it takes. If you have a tractor, turning is relatively easy. If you're doing it by hand, turning every week or two is enough to keep the process active without being overwhelmingly labor-intensive. If you never want to turn your pile, accept that it'll take a year or more to get finished compost.

Fourth, monitor your pile for problems. Is it getting too wet and starting to smell bad? That means it's becoming anaerobic—turn it or add carbon-rich material like excess shavings to improve aeration. Is it drying out? Add water or cover it less. Is it not decomposing quickly? That could mean it needs turning, or it might need more nitrogen if it's mostly bedding without much manure. Pay attention to how your pile is behaving and adjust your management accordingly.

Fifth, know when your compost is finished. You're looking for dark color, crumbly texture, and earthy smell. When it looks like that, it's ready to use. Partially finished compost can be used on pastures and it'll continue decomposing. Finished compost can be used anywhere—pastures, hay fields, gardens, landscaping.

Using finished compost is the payoff for your composting effort. You can spread it on pastures in spring or fall to improve soil. You can use it in vegetable gardens or landscaping. You can give it away to neighbors or friends who want compost for their gardens. A horse owner composting manure can generate several yards of finished compost per horse per year, which is valuable material for land improvement.

Composting saves money compared to other manure disposal methods. Hauling manure away costs money—either you're paying someone to haul it, or you're spending time and fuel doing it yourself. Spreading raw manure on pasture works but spreads parasites and weed seeds and can burn grass in high concentrations. Composting converts waste into a resource instead of a disposal problem. Once your initial compost bin or pile location is set up, ongoing composting costs almost nothing. You're moving material you're already removing from stalls anyway, just to a different location.

The initial investment in a compost system is minimal. An open pile costs nothing beyond choosing a location. A three-bin system from pallets might cost $100 to $200 for building materials. A purchased compost bin might cost $300 to $800 depending on size and quality. These are one-time investments that pay for themselves through the value of compost you produce and the disposal costs you avoid. Most people recoup their investment within a few years.

Planning your compost system should account for how much material you're generating. One horse generates a lot of manure. If you're just composting for a few horses and you have land to use the finished compost on, a simple open pile or small bin might work fine. If you have multiple horses or limited land, you might want a larger or more sophisticated system. Plan based on your actual waste stream and your actual capacity to manage the system.

One consideration is whether you're composting just for your own use or whether you might eventually give away or sell finished compost. If you might offer it to neighbors or friends, a neater, better-managed system looks better and is easier to manage. If you're composting solely to manage your own waste, a simple approach is fine. Either way, the goal is having a system that actually works for your situation rather than a system that's too complicated or too elaborate and doesn't actually get maintained.

Composting is one of the easiest environmental improvements a horse owner can make. You're managing waste responsibly, creating a useful soil amendment, and improving your land all at the same time. Even a simple, unmanaged pile eventually becomes compost. A managed pile produces finished compost in months instead of years. Invest the small amount of effort to manage your pile well and you'll have valuable compost instead of a pile of manure sitting in your pasture for years.