Turning Horse Manure into Gardener’s Gold: A Comprehensive Guide to Composting

Horse manure, often seen as a byproduct of equestrian activities, is actually a treasure trove of nutrients and beneficial microbes. When properly composted, it transforms into a rich soil amendment, perfect for boosting plant growth and improving soil health. This guide provides a detailed, step-by-step approach to composting horse manure effectively, covering everything from the basic principles to advanced techniques.

Why Compost Horse Manure?

Before diving into the ‘how,’ let’s explore the ‘why.’ Composting horse manure offers a multitude of benefits:

• Rich in Nutrients: Horse manure is a good source of nitrogen, phosphorus, and potassium (NPK), the primary macronutrients needed for plant growth. It also contains various micronutrients essential for overall plant health.
• Improved Soil Structure: Compost adds organic matter to the soil, improving its structure. This leads to better water retention, aeration, and drainage.
• Beneficial Microbes: Compost is teeming with beneficial bacteria, fungi, and other microorganisms that break down organic matter, release nutrients, and enhance soil fertility.
• Weed Seed Reduction: The high temperatures generated during proper composting kill many weed seeds, reducing future weed problems in your garden.
• Reduced Landfill Waste: Composting manure diverts it from landfills, reducing your environmental footprint.
• Cost-Effective: Using composted manure is a cost-effective alternative to purchasing commercial fertilizers.

Understanding the Composting Process

Composting is a natural decomposition process driven by microorganisms. These microbes need a balanced environment to thrive, which includes:

• Carbon (Brown) Materials: These provide energy for the microbes. Examples include straw, wood shavings, dried leaves, and shredded cardboard.
• Nitrogen (Green) Materials: These provide protein for the microbes. Horse manure is a good source of nitrogen, although it’s relatively low compared to other green materials.
• Water: Moisture is crucial for microbial activity. The compost pile should be damp, like a wrung-out sponge.
• Air (Oxygen): Aerobic microorganisms are the most effective at composting. Turning the pile regularly provides oxygen.

The ideal carbon-to-nitrogen (C:N) ratio for composting is around 25:1 to 30:1. Horse manure itself has a C:N ratio of about 25:1. Adding carbon-rich materials is usually necessary to achieve an effective C:N ratio, as the bedding in the horse manure tends to be relatively high in carbon already. However, this bedding can vary so it is important to monitor the composting process and adjust as necessary.

Step-by-Step Guide to Composting Horse Manure

Here’s a comprehensive guide to composting horse manure, from setting up the compost system to using the finished compost:

Step 1: Choosing a Composting Method

There are various methods for composting horse manure. The most common are:

1. Pile Composting (Open-Air Windrows): This involves creating a large pile of manure and other materials directly on the ground. It’s the simplest and most cost-effective method for larger quantities.
2. Bin Composting: Using a compost bin or tumbler provides better containment and can be more aesthetically pleasing, suitable for smaller gardens. Bins can be purchased or homemade.
3. Sheet Composting (Direct Application): This involves spreading a thin layer of manure directly onto the garden bed or between rows. This is most effective when starting new beds and requires proper curing. It is also frequently used in large scale farming.
4. Aerated Static Pile: This method involves a pile built with perforated pipes at the base to allow airflow. This is beneficial for large scale composting and speeding up decomposition.

For this guide, we will focus primarily on pile composting, but many of the principles can be applied to other methods.

Step 2: Selecting a Location

Choose a location that is:

• Well-Drained: Avoid areas that collect water, as this can lead to anaerobic conditions and foul odors.
• Accessible: Ensure the location is easy to reach for turning and adding materials.
• Away from Waterways: To prevent nutrient runoff, locate the compost pile away from streams and ponds.
• Sufficiently Large: The compost pile should be large enough to retain heat effectively. At least 3ft x 3ft x 3ft is recommended, for larger piles you can go significantly larger.

Step 3: Gathering Materials

You’ll need the following materials:

• Horse Manure: Including both solid manure and urine-soaked bedding. Be careful when adding wood shavings that may have been treated with chemicals as this can negatively impact the composting process.
• Carbon-Rich Materials: Such as straw, wood shavings, dried leaves, shredded cardboard, or newspaper. Aim to create a good mix of carbon and nitrogen materials. As a general rule, equal parts is a good starting point, but be prepared to adjust.
• Water: A hose or watering can is needed to moisten the pile.
• Pitchfork or Shovel: For turning the pile.
• Optional: A compost thermometer for monitoring the pile’s temperature and a tarp to cover the pile when it rains, which can slow down the process and make the pile anaerobic.

Step 4: Building the Compost Pile

Follow these steps to build your compost pile:

1. Layering: Begin by layering a 4-6 inch thick layer of carbon-rich materials such as straw on the ground. This creates a base that provides aeration and drainage.
2. Adding Manure: Add a layer of horse manure on top of the carbon-rich layer, also around 4-6 inches thick.
3. Repeat Layers: Continue layering the carbon and nitrogen materials until your pile is at least 3ft high, as high as 5ft may be more efficient.
4. Watering: Moisten the pile with water as you build. Aim for a damp, not soggy, consistency.
5. Pile Formation: Create a wide base and taper towards the top to help the pile retain heat and prevent collapse.
6. Avoid compaction: Do not step on the pile while creating it as this will reduce air circulation and slow the composting process.

Step 5: Turning the Compost Pile

Turning the compost pile is crucial for introducing oxygen and ensuring even decomposition. Follow these guidelines:

• Initial Turn: Turn the pile for the first time after about 5-7 days, or when the pile starts to heat up significantly.
• Regular Turning: Turn the pile every 3-5 days. If the pile is very large, it is acceptable to turn less often as the internal heat will create better decomposition, but may take longer.
• Proper Technique: Use a pitchfork or shovel to mix the materials thoroughly, moving the outer layer to the center and the inner layer to the outside.
• Moisture Check: Check the moisture level each time you turn. If it is dry, add water as needed.
• Temperature Monitoring: Use a compost thermometer to monitor the internal temperature of the pile. The ideal temperature for composting is 130-160°F (55-70°C). If the temperature falls below 100°F (40°C), it’s a sign that the pile may need to be turned or have more nitrogen-rich materials added. If the pile is above 160°F (70°C), then the pile may not have sufficient aeration and needs to be turned immediately to prevent anaerobic conditions.

Step 6: Monitoring and Adjusting

Pay attention to these indicators throughout the composting process:

• Temperature: The pile should heat up within a few days, indicating active microbial activity.
• Moisture: The pile should be damp but not soggy. Add water if it is too dry. Avoid oversaturating the pile.
• Odor: A properly composting pile should have a pleasant, earthy smell. Foul odors indicate anaerobic conditions, usually caused by excessive moisture or lack of oxygen.
• Visual Inspection: Observe the texture and color of the compost. As the pile decomposes, the materials will break down, and the pile will become a dark, crumbly substance.
• Adjustments: Based on your observations, adjust the moisture level, turning frequency, and carbon/nitrogen ratio as needed. If the pile is too wet, add more carbon materials. If it is too dry, add water. If the pile is not heating up, consider adding more nitrogen-rich materials or ensuring sufficient moisture and airflow.

Step 7: Curing the Compost

Once the pile has stopped heating up and the materials have broken down significantly, it’s time to cure the compost. Curing is a critical step for developing the beneficial microbial population and stabilizing the nutrients.

• Separate Curing Pile: Move the compost to a separate curing pile, or a bin if you prefer.
• Reduce Turning: Reduce turning frequency during the curing phase. Turn every 7-10 days.
• Moisture Control: Maintain a damp, but not soggy, moisture level.
• Curing Time: Allow the compost to cure for 4-8 weeks.

During the curing period, the compost will undergo further microbial activity, breaking down any remaining organic matter and ensuring that it is safe for use in your garden.

Step 8: Testing the Compost

Before using the compost, it’s important to test for its maturity:

• Visual Inspection: The compost should be dark, crumbly, and have a pleasant earthy smell. There should be no identifiable pieces of manure or bedding material.
• Seed Germination Test: Place a sample of the compost in a small container. Sow some fast-growing seeds, like radish or cress, and monitor their growth. If the seeds germinate and grow well, the compost is likely mature. If the seeds do not germinate, then it is likely that it is not mature.
• pH Test: Use a soil pH test kit to check the pH of the compost. It should be in the range of 6.0-7.0.

Step 9: Using the Finished Compost

Once the compost is cured and tested, it’s ready to use in your garden. Here are some ways to incorporate it:

• Soil Amendment: Mix compost into your garden beds when planting.
• Top Dressing: Apply a thin layer of compost around established plants.
• Potting Mix: Use compost as an ingredient in your own potting mix.
• Mulch: Use compost as a mulch around plants to help retain moisture and suppress weeds.

Troubleshooting Common Problems

Here are some common issues that might arise and how to address them:

• Pile is Not Heating Up: This could be due to insufficient nitrogen, moisture, or oxygen. Add more nitrogen-rich materials, water, or turn the pile more frequently.
• Pile Smells Foul: This indicates anaerobic conditions. Turn the pile to introduce more oxygen and reduce moisture.
• Pile is Too Wet: Add more carbon-rich materials, such as straw or wood shavings, and turn the pile frequently.
• Pile is Too Dry: Add water and turn the pile.
• Slow Decomposition: Ensure the pile has a good balance of carbon and nitrogen, and the pile is kept moist and well-aerated.
• Presence of Flies or Rodents: A properly managed compost pile will not attract pests, as flies and rodents are attracted to wet, anaerobic environments. If pests are a problem, ensure the pile is not overly wet, and bury food scraps to prevent exposure.

Advanced Techniques

For those who want to take their composting to the next level, here are a few advanced techniques:

• Vermicomposting: Use worms to break down the manure and other organic matter.
• Hot Composting (The Berkeley Method): Follow a specific turning schedule to achieve high temperatures and rapid decomposition.
• Compost Tea: Brew compost with water to create a liquid fertilizer.
• Adding Beneficial Inoculants: Introduce microbes such as lactobacillus or fungi to accelerate the process.

Conclusion

Composting horse manure is a rewarding process that benefits both your garden and the environment. By following this comprehensive guide, you can turn horse manure into a valuable resource, improving your soil health, plant growth, and overall gardening experience. Remember, composting is a dynamic process, so don’t be afraid to experiment and adjust your approach as needed. Happy composting!