Backyard Composting

What is composting?

Hot composting is a managed process to quickly break down organic matter (leaves, grass,vegetables) primarily through heat-producing microorganisms (bacteria) into a soil-like product. Hot composting can produce compost in 30 days to 3 months and kills most weed seeds and pathogens. It requires large amounts of materials at one time and fairly intensive maintenance.

Cold composting is a managed process to slowly break down organic matter using mircroorganisms and invertebrates under outdoor temperature conditions. Cold composting is similar to decomposition processes in the natural environment. Most backyard composters use the cold composting methods when they place materials in a pile. It takes 1-2 years for the materials to completely break down and it does not kill weed seeds or pathogens.

Why compost?

• Increase nutrients and moisture in the soil.
• Improve the structure of clay and sandy soils.
• Eliminate air pollution from burning leaves.
• Reduce waste by 20% - 40% going to landfills. (Michigan law prohibits yard wastes from landfills)
• Save gas and energy required to transport and process yard waste and kitchen scraps.
• Create healthy soil for beautiful gardens in your landscape.

How do you compost?

Materials that can be used for both hot and cold composting

• Brown (carbon) source - leaves, sawdust, hay, corncobs, wood chips.
• Green (nitrogen) source - grass clippings, coffee grounds, vegetable wastes, aquatic weeds, manure, pine needles.
• Sources to AVOID - meat or animal products, oils, dog or cat feces, diseased plants, invasive weeds, long-lived chemicals like Arsenic, coal or charcoal ashes. - these materials can attract wildlife pests, spread disease or add toxic substances to the pile.
• Additives or inoculants - these products contain bacteria and nitrogen usually found in organic matter and soil. If an additional nitrogen source is needed, alternatives include ammonia sulfate, calcium nitrate, urea, dried blood, or fish meal.
• Water and Soil
• Pitch fork or shovel
• Bin or area to place pile

Hot Composting Recipe

• Mix 1 part Green, 2 parts Brown
• Add soil (several shovel's full)
• Add water and mix to make it as wet as wrung out sponge.
• Turn every few days or once a week, when the pile starts to cool down, placing the materials on the outside of the pile into the inside. The pile should heat up after you turn it and cool down after several days.
  After 1-3 days, the inside of the pile should be hot to the touch (130- 160 degrees) and the outside will be warm due to bacterial activity.
• Turn and maintain moisture level for 1-3 months until compost is formed. It should be dark brown with a sweet, earthy-smelling odor.
• Cure, if desired, in a pile for 6-12 months.
• Continue the process as desired.

Cold Composting Methods

• Pile or Bin - place materials in a pile, mixing brown with green materials if possible. Let it decompose for 1-2 years. (A perforated PVC pipe can help get air into the pile and help to decompose the materials faster.)
• Sheet Composting - in the fall, spread leaves, grass and other yard waste 6 inches thick over a garden plot. Mix with the top few inches of soil (if possible) to help the decomposition process. In the early spring, till the materials into the soil.
• Trench and Pit Composting - dig a trench or hole at least 1 foot deep. Bury yard waste and fruit and vegetable scraps in the hole or trench, covering with at least a few inches of soil. The trench can be used as a row for planting crops and the hold can be used to plant a tree.
• Mulching - spread a 3-6 inch layer of leaves, grass and other yard waste on the soil around plants. (Avoid piling mulch too deep - more than 3 inches - around the base of plants.)
• Grasscycling - let grass clippings stay on the ground where they will decompose and enrich the soil. Cut the grass high (3-4 inches) when it is dry, leaving at least 2/3 of the blade. Pick up excess clippings when necessary to use in compost pile.
• Worm Composting - Check this page to see how you can let red worms do the composting for you!

Bins or Piles

• Size - at least a 3 feet X 3 feet X 3 feet enclosure or pile for hot composting. Any size bin works for cold composting.
• Placement - near water source, good drainage, away from wood on building, near garden, out of sun and wind. Worm bins should be kept indoors or in a garage where there are no extremes of temperature.
• Types of Materials - chicken wire, pallets, snow fence, cinder blocks, plastic bins. Form in a circle or square with easy access for turning. Use twine to attach four pallets together and fencing posts to secure chicken wire in a circle or square.
• Cost for bins - range from free for pallets to $90+ for commercial bins.

Tips

• Shred or chop materials before adding to a pile or bin (especially a worm bin).
  • Stockpile leaves in the fall to mix with green materials (grass clippings) in the spring.
  • Turn the pile frequently to speed up decomposition.
  • Build a series of two or three turning units or bins for large volumes of yard wastes. When the pile cools, turn it into an adjacent bin.

  
  Concerns and Solutions

  Pesticides and herbicides - in general, if the compost is cured from 6-12 months, pesticide and herbicide residues should not be a problem.

  • Odors - Add carbon source, mix. Add wood ashes or crushed eggshells.
  • Low pile temperature - add water, increase pile size and add nitrogen source.
  • High pile temperature - decrease pile size, add carbon source.
  • Pests - remove animal products, add carbon source and/or use animal-proof bin.

   

  Uses of Finished Compost
  

  • Substitute for topsoil, especially if you've added fertilizer or manure and soil during the composting process.
  • Mulch around shrubs and trees.
  • Screen the compost and use as a seed-starting material or as a top-dressing on lawns.
  • Work compost into the top 2-3 inches of soil.
  • Mix with topsoil for use with indoor potting plants. Sterilize by baking in a 200-degree oven for one hour.

Prepared by MSU Exension, Genesee County.

Michigan State University Extension programs and materials are open to allwithout regard to race, color, national origin, gender, religion, age,disability, political beliefs, sexual orientation, marital status, or family status. MSUE-Genesee County is funded jointly by Michigan State University, the U.S. Department of Agriculture and the Genesee County Board of Commissioners. MSU is an affirmative-action equal opportunity institution.