Windrow Compost—Large Scale Composting

Windrow compost is aerobically produced decomposed organic material. This large scale composting process creates heat that destroys pathogens and produces a compost product for use as mulch, soil conditioner, and topsoil additive.

The organic material is decomposed outdoors, helped only by watering and regular mechanical turning for air circulation.

The windrow composting process is simple and very low cost. It's used by farmers, cities, and waste processing companies.

(This composting method isn't for you unless you have a large property and a lot of organic material available.)

It's a slow, large-scale method of producing compost (however, it's primary function in cities is to reduce the amount of organic waste going to landfills). The windrow compost method can be used to process yard waste, food, paper, and even sewage sludge.

The Composting Process

This process begins with the gathering, sorting and storing of the organic materials to be composted. They must be screened or hand picked for objects that will not decompose. The remaining material is chipped, ground, or shredded into uniform particles that will decompose quickly.

If windrow composting is used to process high carbon, dry materials, such as wood and paper waste, equal parts of high nitrogen materials need to be added. This can be grass clippings or food waste, which will ensure balanced nutrition for the decomposers in the pile.

The materials are mixed with a paddle-blade mixer and the windrow is constructed using earth-moving equipment (usually a backhoe or front-end loader).

windrow compost pile
Photo courtesy of the
Environmental Protection Agency

These piles are typically 1.5 to 3 feet high, 3-6 feet wide, and up to 100 feet or more in length.

Oxygen levels and temperatures must be maintained to provide optimum conditions for the microorganisms. The temperature must be high enough to kill pathogens and weed seeds but not so high that it kills the microorganisms.

Oxygen is a primary need for aerobic decomposition. A well aerated and properly mixed compost pile will not have any unpleasant odors.

The windrows are aerated mechanically by turning with a front end loader.

After the composting period, the windrows are reconstructed into curing piles for additional aging and drying of the material. Curing compost stabilizes it, which prevents odors and other nuisances from developing while the material is stored.

After curing, the compost may be screened to improve the quality of the final compost product.

The Benefits of Windrow Compost

  • Large-scale composting, which reduces large amounts of waste.
  • Easy to use and operate.
  • Low operating costs, especially when compared to dumping organic materials into landfills.
  • Less equipment and maintenance needed than other methods.

Disadvantages of Windrow Compost

  • A large amount of land needed for the composting process.
  • Requires large adjacent areas due to odor and vectors.
  • It may attracts scavengers and pests.
  • Odors may be produced (although properly managed, there should be few odors).
  • Rainwater runoff maintenance is required.
  • Compost can become anaerobic under rainy conditions.

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