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Managing and composting horse manure

Quick facts

  • A 1,000-pound horse eats about 2 percent of its body weight and produces 10 tons of manure a year.

  • Always follow state guidelines for storing manure.

  • Good composting locks in the nutrients, speeds up the breakdown, and kills weed seeds and fly larvae.

  • Don’t spread manure on pastures with more than one horse per two acres.

  • All barns should have a manure management plan. 

Managing manure is key to responsible horse ownership regardless of how many horses you own or manage. Farmers consider manure a valuable nutrient resource for soils.

Production and characteristics

The average 1,000-pound horse eats about 2 percent of its body weight and drinks 10 to 12 gallons of water daily. This will vary with individual metabolism, activity level, and the weather.

On average, that same 1,000-pound horse will pass 55 pounds of manure (feces and urine combined) each day. This adds up to more than 10 tons each year.

Of that 55 pounds of fresh manure excreted daily, there is roughly 0.2 pounds of nitrogen, 0.05 pounds of phosphorus, and 0.12 pounds of potassium (K). These are just averages, though, and depend on your horse's activity levels and feed. Plus, bedding may influence the nutrients in the manure, as well. It is always a good idea to regularly test your manure so that you know what you are working with.

Storage

Normally, manure storage consists of:

  • Short-term stockpiling

  • Permanent stockpiling

  • Composting

  • Spreading the manure

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Composting

Pile of manure that is well mixed.
Well mixed raw ingredients for compost

Composting is managed, accelerated breakdown of organic materials by microbes (i.e. bacteria, fungus and molds). The goal of the composting process is to provide these microbes with a good environment that encourages quick and efficient manure breakdown. Effective composting does the following.

  • Locks in nutrients

  • Speeds up the breakdown process

  • Reduces the size of the pile

  • Kills weed seeds and fly larvae

A manure pile will eventually breakdown if left alone but will lose nutrients and become infested with unwanted organisms.

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Using manure

Whether composted or not, you will eventually need to move and use the manure. You can use manure onsite by spreading it as a fertilizer on an open area, pasture or field.

You can also haul manure offsite for fertilizing or composting. Use caution when spreading manure on pastures grazed by horses. Don’t spread manure on pastures if there are more than 1 horse per 2 acres. Spreading manure in heavily stocked pastures could result in increased parasite exposure.

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Develop a manure management plan

All horse facilities should have a manure management plan, which includes:

  • Estimating yearly animal manure production

  • Estimating yearly nutrient production

  • Plans for collecting, handling and storing

  • Emergency action plan that quickly deals with accidental manure spills or other environmental emergencies

  • If you plan to apply the manure to the land, include the following in addition to the above:

    • Estimating yearly crop nutrient use potential

    • Rotating crops

    • Available land for application throughout the year

Author: Betsy Wieland, former Extension educator

Reviewed in 2021

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