How to Compost Manure

Medically Reviewed by Poonam Sachdev on January 11, 2023

Composting is an excellent way to recycle organic waste. For those who live on a farm or have animals like horses, cows, and chickens, that waste includes manure. Manure composting gives you a way to get rid of the waste from your animals, and you’ll get something that nourishes your plants in return. 

What Is Composting?

Composting is the process of piling together organic material so that microorganisms, like bacteria and fungi, can break it down to create a nutritious fertilizer.

When you compost, it allows organic material to be recycled in a way that’s usable and safe. Adding compost to soil increases the soil’s health and helps it retain moisture, which in turn helps your crops or gardens thrive. It’s a great way to take waste and turn it into something valuable.

Benefits of Composting Manure

While composting in general has many benefits, there are some specific benefits to turning your manure into compost.

Composting kills dangerous pathogens in manure. During the composting process, the microorganisms raise the temperature inside the compost pile as they work to decompose the organic material. These high temperatures kill off things like bacteria, parasites, and viruses that might be present in the manure, making it safe to use. 

E.coli is a large concern with fresh manure, and as a result, fresh manure shouldn’t be used on fruits and vegetables. Composting will kill bacteria likeE.coli, allowing you to safely fertilize your growing produce without fear of contamination.

Composting neutralizes the odor of manure. To say that manure smells bad may be a bit of an understatement. Manure has an awful stench, but compost doesn’t. The smell of compost is usually earthy, and unless you’re doing something wrong, it shouldn’t be unpleasant. 

Composting reduces the volume of manure. You may have a lot of manure now, but once the composting process is done, you’ll have a lot less. That’s because composting reduces the initial volume of your organic waste by 30% to 50%. This can give you a more manageable amount to work with while also freeing up storage space.

A few other benefits of composting manure:

  • Composting doesn’t attract flies and other pests the way manure does.
  • If compost gets into your water, it doesn’t pollute it the way manure would.
  • Composting has a more appealing look overall than manure, so you can put it in your garden without worrying about what it will look like.
  • Animals grazing in fertilized areas won’t be spreading around raw manure.
  • Plants, especially grass, grow more easily through compost than through manure.

What to Compost With Manure

You can compost most kinds of organic materials, but you need a mix of materials for your compost pile to work well. The microorganisms inside your compost pile need both carbon and nitrogen to grow and thrive. 

Raw manure is high in nitrogen but doesn’t have enough carbon for the microorganisms. To fix this, your manure needs to be mixed with high-carbon items, also called “brown” items. Most brown items are “woody,” that is, they come from trees. Some examples of carbon-rich items you can mix into your compost pile include:

  • Branches and twigs
  • Dead plant clippings
  • Dry leaves and grass
  • Hay
  • Paper and newspaper
  • Pine needles
  • Sawdust
  • Straw

While the temperature of your compost pile should be high enough to kill any pathogens, avoid adding diseased or infested plants to your compost pile. Plants treated with herbicides or pesticides should stay out as well. 

The microorganisms in your compost pile need more carbon than nitrogen. The ideal ratio of carbon to nitrogen is 25 to 30 parts carbon per one part nitrogen. Adding brown materials to your manure helps you reach this ratio and also lowers the moisture content so your compost pile doesn’t get too wet.

How to Compost Manure

Your manure composting system doesn’t have to be complicated. Once you’ve mixed your manure and carbon-rich products, the microorganisms will take over and do most of the heavy lifting.

  1. Choose a spot for your compost pile. The best spot to put a compost pile is somewhere dry and shady. You may also want to set up your pile near the animals that you’re getting the manure from, just to make things easier on yourself. 
  2. Decide how to get oxygen to your manure compost. The microorganisms inside your compost pile need oxygen to do their job. To ensure your pile gets enough oxygen throughout, you can lay down pipes to push oxygen through the compost pile, or you can periodically mix the compost pile with a tractor or loader.
  3. Set up your compost pile. Mix the items in your pile so the microorganisms have access to both carbon and nitrogen. The best size for a compost pile is 3 feet by 3 feet. Any smaller, and the temperature won’t get high enough. Any larger, and air can’t reach the center.
  4. Monitor your compost pile. Check in regularly to make sure the moisture levels and temperature levels are in range.

You want your compost pile to be about as damp as a wrung-out sponge. If you aren’t sure, try squeezing a handful of compost in your fist. It should leave a thin layer of moisture on your hand. If water comes out when you squeeze it, your pile is too wet. If the compost crumbles, it’s too dry. 

Your compost pile should be at least 110°F (43.3°C). The ideal temperature range is between 130°F and 140°F (54.5°C and 60°C). To kill pathogens, your compost needs to be over 131°F (55°C) for at least three days. If your compost isn’t getting up to 110°F, either something is wrong or the composting is finished.

How Long Does It Take to Compost Manure?

While it can depend on the specifics of your manure composting method, in the right conditions, your compost should be done in three or four months. If you’re not as vigilant, it could take closer to six months.

To tell if your compost is done, check whether:

  • The compost is a dark, rich brown.
  • The compost smells earthy, like dirt.
  • The compost looks uniform; you can’t distinguish the manure from the other materials.
  • The compost pile no longer stays above 110°F.

Once your compost is finished, you can use it to nourish your garden or crops or spread it over your lawn or pasture. 

The best time to spread compost in the U.S. is from late August to early September. Don’t spread your compost between November and February if you live in areas that get frost and snow. Grass and most plants are dormant at this time, and the compost will have no benefit and likely just wash away.

Show Sources

EcoMyths: “Myth: Hold Your Nose — Composting Stinks!”
King Conservation District: “How to Compost Manure.”
Michigan State University: “Animal manure compost.”
National Resources Defense Council: “Composting 101.”
Sierra: “Composting 101: Hooray for the Black, Brown, and Green.”
University of Wisconsin-Madison: “Using Manure in the Home Garden.”
Urban Agriculture: “Composting and Water Conservation.”

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