Horse manure can be an excellent addition to gardens and compost piles when handled properly. As an organic material rich in nutrients, horse manure provides numerous benefits for improving soil health and plant growth. However, fresh manure also contains pathogens that can harm plants or contaminate produce, so proper composting is essential before using horse manure in the garden. This article will explore the many advantages of using horse manure as well as provide key techniques for successful composting that eliminates risks and maximizes the value of this organic resource.

Benefits of Horse Manure

As an organic material, horse manure adds valuable nutrients and organic matter to improve the health and fertility of garden soils. Here are some of the top benefits of using properly composted horse manure.

  • Nutrient content – Horse manure contains nitrogen, phosphorus, and potassium – key macronutrients plants need to thrive. The nitrogen encourages leafy growth, phosphorus aids root and flower development, and potassium supports overall plant health.
  • Organic matter – The organic materials in manure feed soil organisms and earthworms while retaining moisture and improving soil structure and aeration. This creates optimal conditions for plant root systems.
  • Soil health – The nutrients and organic matter boost the overall health of soil by increasing its water retention, drainage, and nutrient holding capacity for stronger, healthier plant growth.
  • Slow release fertilizer – Composted manure provides a slow-release of nutrients over time compared to synthetic fertilizers that may quickly leach from soil. This gives plants a consistent source of nourishment.
  • Humus content – Manure adds stable, long-lasting humus to soil after composting. Humus further enhances moisture retention, drainage, and soil structure for better plant health.
  • Free fertilizer – Using composted manure is an effective way to fertilize gardens organically without the need to purchase commercial fertilizers. This makes it a cost-effective soil amendment.

Proper Composting Techniques

To gain all the benefits that horse manure offers, proper composting is essential. Raw, fresh manure contains pathogens such as E. coli that can persist in soil and contaminate gardens. Thorough composting eliminates weed seeds and disease-causing organisms to make the manure safe for garden use. Here are some key tips for successful composting:

Site Selection

  • Select a level, well-draining site away from any water sources or food gardens to prevent runoff or contamination. Avoid low-lying areas.

Pile Size

  • Compost piles should have dimensions of at least 3 feet x 3 feet x 3 feet (equivalent to 1 cubic yard) to produce enough heat for effective composting. While the width and height should maintain these dimensions, the length of the pile can be extended as space permits.


  • The pile needs proper aeration to encourage aerobic bacteria. Turn or mix the pile with a pitchfork weekly and add coarse materials like straw or wood chips to allow air pockets.


  • Optimal moisture is key for microbial activity. The pile should always feel damp but not soaked. Add water while turning if needed to maintain moisture around 50-60%.

Carbon & Nitrogen Ratio

  • Shoot for an ideal C:N ratio of 25-30:1 by adding carbon-rich “brown” materials like straw, leaves, or sawdust to balance the nitrogen in the manure.


  • Actively composting manure will take 4-6 months to fully stabilize & neutralize pathogens. Let the finished compost cure for several more months before use.


  • Internal temperatures should reach 130-150°F to kill pathogens and weed seeds. Use a compost thermometer to monitor this.

Ingredients to Avoid

  • Do not add cat or dog feces, meat, oils, dairy, treated seeds, or diseased plants to the compost pile. This can introduce pathogens.

Protecting Water Sources

  • Position the pile uphill and at least 200 feet away from any wells, streams, or bodies of water to prevent runoff contamination.

When constructed and managed properly using these techniques, a horse manure compost pile will produce an abundant supply of rich, nutritious compost for amending garden beds and enhancing soil. With its excellent nutrient content and soil conditioning abilities, composted horse manure is one of the best organic materials gardeners can use for boosting landscape and garden health in an eco-friendly manner. By investing some time and effort into the composting process, anyone can safely unlock the full benefits of horse manure for their home gardens.

Using Mature Horse Manure Compost in the Garden

Once the horse manure has finished composting completely, it is ready to use around the garden. Here are some tips for getting the most benefits from the finished compost:

  • Spread compost 3-6 inches deep over garden beds and work it into the top 6-12 inches of soil. This depth ensures plant roots have access to the nutrients and organic matter.
  • Ideally, apply compost a few weeks before planting to allow the microbiology in the soil to stabilize before sowing seeds or transplanting.
  • Mixing equal parts compost and native soil makes an excellent potting mix for containers and raised garden beds. The compost improves drainage and nutrient retention.
  • Top-dress existing plants by applying a 1-2 inch layer of compost around each plant, keeping it away from stems. Water in well to encourage root uptake.
  • Make compost “tea” by soaking some compost in water for a day or two. The resulting nutrient-rich tea can be used to water plants as an organic fertilizer spray.
  • Use compost as a side-dressing for vegetables, flowers, trees, and shrubs throughout the growing season by digging shallow trenches alongside rows and mounding compost into the trenches.
  • Distribute compost around the base of trees and shrubs, extending to the drip line or beyond, to enrich the soil biology and supply essential nutrients.
  • Till aged compost into garden beds in autumn after clearing out spent plants. This replenishes the soil before going dormant over winter.

With proper application of finished compost made using suitable composting techniques, gardens benefit from horse manure’s excellent properties each season. While raw manure poses risks, taking the time to compost horse waste correctly allows gardeners to safely unlock its full potential for achieving vibrant, bountiful backyard harvests.

Troubleshooting Common Composting Problems

Even when following the proper composting methods, some issues can arise. Here are some common composting problems and how to fix them:

Pile doesn’t heat up – The compost needs more nitrogen-rich materials or moisture. Mix in manure, grass clippings, food scraps and water while turning.

Pile smells like ammonia – Too much nitrogen. Add carbon materials like sawdust, straw, or leaves to rebalance the C:N ratio.

Pile smells rotten – There is too much moisture. Turn the pile and add woody items like branches or corn cobs to improve aeration.

Pile is damp but won’t heat up – Lack of oxygen is slowing microbial activity. Turn the pile and make sure aeration is adequate.

Pile attracts flies and pests – Exposed food scraps or manure is drawing pests. Cover scraps with compost, leaves or a tarp.

Weeds growing in finished compost – Weed seeds did not get hot enough to kill. Re-compost the batch to heat it sufficiently before using.

Animals disturb open pile – Enclose the compost in a bin made of wire, wood, or plastic to keep animals out.

Patience is key with composting. Monitor conditions like moisture, aeration, and temperatures. With minor troubleshooting adjustments, your compost will be ready for nutritious, organic gardening in no time.

Final Thoughts

While requiring more time and labor than purchasing synthetic fertilizers, proper composting of horse manure creates a free, organic soil amendment that greatly enhances gardens and landscape soil. With its concentrated mix of slow-release nutrients and humus-building organic matter, horse manure compost boosts soil health, plant vigor, moisture retention, and nutrient holding capacity for healthier plants and bountiful harvests. By selecting the right location, maintaining optimal conditions, and troubleshooting any issues, gardeners can avoid the risks of raw manure and safely transform horse waste into “black gold” for their gardens.