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Composting Basics
Finished compost. Photo courtesy of the Mid-Atlantic Equine Pasture Initiative.
Composting is a process where microorganisms convert organic materials such as manure, bedding, leaves, and grass clippings into a soil-like material called compost. Compost can be added to our lawns and gardens to enhance the soil with nutrients, organic matter and other minerals to benefit the plants that are growing there.
Compost piles are also sources of nutrients and pathogens, so they should be properly located and managed using the same guidelines as manure storage areas.
When done correctly, compost is free of pathogens and weed seeds. Piling manure and just letting it sit is not really composting. Composting is an active process that includes the following:
Adequate oxygen and air flow – this involves mechanical turning or introducing air flow through the pile using perforated pipe. A powered blower can be used to increase air flow.
Heating the pile to high enough temperatures (130 – 150 degress F). Compost thermometers can be purchased from local garden supply stores.
Enough moisture – 40 to 60 percent moisture content; it should feel like a wrung-out sponge.
The right mix of materials – the carbon:nitrogen ratio or C:N ratio should be 25:1 to 30:1 (ideal) with 20:1 to 40:1 generally allowing for good results.
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| Manure that contains a lot of wood bedding (shavings, sawdust, etc.) can result in a high C:N ratio. Nitrogen sources may need to be added to the compost pile in the form of grass clippings, additional raw manure or even nitrogen fertilizer.Switching to straw bedding can help. When using straw for bedding, consider chopping it prior to use. |
Average C:N ratios for various materials
| Material | C:N ratio |
| Raw manure | 14:1 to 30:1 |
| Grass clippings | 17:1 |
| Hay (non-legume) | 15:1 to 32:1 |
| Leaves | 54:1 |
| Straw | 80:1 |
| Sawdust and Woodchips | 500:1 |
Information taken from On-Farm Composting Handbook, Natural Resource, Agriculture and Engineering Service.
Composting Examples
Photo courtesy of University of New Hampshire Cooperative Extension.
This is a small wooden compost bin that sits on an impervious surface and is covered with a tarp. Two perforated pipes are placed within the pile to assist with aeration – known as passive aeration.
Photo courtesy of Heidi Konesko, USDA NRCS New Hampshire.
This 3-bin compost system was installed in cooperation with USDA NRCS in New Hampshire. It is an 02 Compost System that uses a blower and perforated pipes located at the bottom of each bin to assist with aeration (forced aeration). The system is roofed and lined with a concrete pad. It provides composting for the manure produced by 5 horses, 1 mule and 14 minature donkeys with wood pellet bedding.
Photo courtesy of the Mid-Atlantic Equine Pasture Initiative.
This is a 6-bin compost system that is roofed and lined with a conrete pad. It relies on mechanical aeration with a small front end loader tractor or it can be turned by hand. One bin starts a new pile of manure and bedding. The pile is then moved to a second bin when it reaches proper temperatures (130 – 140 degrees F). The compost in the second bin is then moved to a third bin (when heated to proper temperatures) to finish or cure.
Photo courtesy of the Mid-Atlantic Equine Pasture Initiative.
This is an open two-bin compost system constructed out of wood and chicken wire and located on a concrete pad. It can be used to stack, move and aerate piles by hand with a fork or shovel. Another bin would be helpful to allow compost to finish or cure.
Photo courtesy of the Mid-Atlantic Pasture Initiative.
This is a windrow compost system where a large front end loader tractor or special windrow aeration machine is used to aerate the piles. It is important to consider lining these areas with a dense gravel or other impermeable liner and directing runoff to grassed filter strips to settle and take up the nutrient and pathogen-rich water.
Composting Resources:
On-Farm Composting Handbook, Natural Resource, Agriculture and Engineering Service – (now plant and life sciences publishing) This handbook presents a thorough overview of farm-scale composting and explains how to produce, use, and market compost.
Composting Horse Manure – UMASS Extension Fact Sheet
On-Farm Composting: A Guide to Principles, Planning, & Operations – Virginia Cooperative Extension Guide.
Horse Manure Management: The Nitrogen Enhancement System – Ohio State Extension fact sheet on adding nitrogen fertilizer to horse manure with a high wood bedding content.
eXtension – Animal Manure Management, Composting
O2 Compost Systems – provides resources and training for establishing on-farm composting systems.
Composting for Small Scale Livestock Operations – Penn State fact sheet providing designs for constructing small compost bins.
Rhode Island Composting Facilities – A Solution For Pollution – brochure listing commercial composting facilities and RI Department of Environmental Management contact information for laws and regulations.
Maine Compost School – provides courses, videos and resource library.
