This diagram provides an overview of the composting process.
Best Management Practice Demonstration Horse Farm
Composting Manure on Equine Farms
Introduction
Compost from horse farms can be used as a soil amendment providing organic matter and some nutrients. Composting manure on small horse farms can be part of an effort to better manage manure and reduce non-point sources of pollution (nitrogen, phosphorus, and pathogens) to drainage basins in New Jersey. Composting produces a stable, volume reduced, and storable product with reduced pathogen levels that conserves some of the nutrients. Compost can be used on- or off-farm when and where the nutrients are needed.
On-farm composting is only a solution when done correctly. If you do not have the time and interest to compost properly, then other methods of manure disposal might be a better option.
What is Composting?
Composting is a managed biological process that converts organic material into a fine particle humus. It is a natural aerobic process for stabilizing organic matter. A series of microorganisms decompose and digest the organic material. Oxygen must be present and heat is generated as the organic material decomposes. In this case, the organic material is horse manure.
- Production of a material more homogeneous than manure
- Final compost is dry, making it easier to spread and manage
- May have marketability (mushroom compost, organic compost, fertilizer)
Please Consider
- Do you have manure or other organic wastes?
- Dead animal or mortality composting?
- Type of farm operation and manure?
- How will composted material be disposed?
- Composting site selection and sizing should be similar to that for a manure storage.
Straw before and after 90 days of composting
How to Compost
Managing mosture, oxygen availbility, and particle size:
- Water is needed for the growth of microbes, transport of nutrients, waste product removal, and mobility of the microbes. A low moisture content slows the composting process.
- Bedding materials that are very fine, have little structure and therefore a low porosity will compost poorly.
- At high moisture content sufficient aeration might be hindered. Consider using bedding with greater porosity.
- Adequate porosity and moisture will allow for proper aeration (oxygen).
- Compost should be turned on a regular basis to ensure adequate aeration of the materials.
Carbon:Nitrogen (C/N) ratio:
- C/N ratios that are too high slow down microbial degradation and ratios that are too low result in the release of nitrogen as ammonia, which is a source of unpleasant odors.
- Optimum C/N ratios at the beginning of the composting process should be between 20/1 and 30/1 but can deviate depending on the carbon source. For example, woody materials (wood shavings or sawdust where carbon is less accessible to microbes) C/N ratios of 35/1 to 40/1 are considered optimum.
Temperature should be measured at least weekly. A temperature probe (thermometer with a 3–5 foot stem) should be placed in the center of the pile at different locations. Proper temperatures can help reduce pathogens and intestinal parasites present in horse manure.
| Material | Carbon/Nitrogen (C/N) |
|---|---|
| Horse feces and urine | 19/1 |
| Straw | 40/1 - 100/1 |
| Wood shavings | 500/1 - 600/1 |
| Sawdust | 400/1 |
| Horse manure | 22/1 - 93/1 |
| Dairy manure | 20/1 |
| Grass clippings | 17/1 |
Temperature probe during composting and composted pelleted straw
Composting Plans
The long term goal is to compost the manure and use most of it as fertilizer on the farm fields and develop a plan for disposing of the remainder off farm. The farm has a long history of offering some raw manure to the general public and for use on university research farms. Current plans are to market a more finished manure compost which can be sold either bulk or bagged.
Bedding Project at the Equine Science Center
A recent project at Rutgers University compared four horse bedding types: straw, a pelleted wheat straw product, a pelleted wood product, and wood shavings. Twelve standardbred horses were stalled on the four bedding types (3 horses per bedding type) for 16 hours per day for a three week period of time. All bedding was collected and use evaluated for: amount of bedding used in the stalls, absorption, air quality and composting characteristics.
Collected bedding