Hot Composting

The compost pile is really a teeming microbial farm. Microorganisms, such as bacteria and fungi, are naturally present on food and yard trimmings added to the pile. These organisms decompose organic material into rich, earthy-smelling organic material. 

The hot compost method depends on heat-loving and heat-generating bacteria. In order for these bacteria to thrive, the pile should be of correct size, have the proper temperature, and have the proper balance of food, water and air. If these conditions are met, the microorganisms will raise the temperature of the pile to 140 degrees or more; hot enough to burn your hand! The heat from this rapid decomposition is enough to kill most weeds and disease-causing organisms.

Proper Balance of FoodJust about anything that was once alive can be composted. Carbon and nitrogen from the cells of dead plants and microorganisms fuel the activity of the decomposing organisms. The ratio of carbon to nitrogen (C:N) is important to a hot compost pile. It helps to think of materials high in nitrogen as "greens," and carbon-rich materials as "browns."

A good guide to get the right balance of greens to browns is to use roughly half browns and half greens when building your pile. A pile that is too high in browns will stay cool and sit a long time without breaking down. A pile too high in greens can get slimy and have a foul odor

Other household organic materials such as wool, cotton, dust, hair clippings, and pet fur can also be composted. 

 
Materials Not to Use

• Food scraps of any kind
• Large branches or logs (unless shredded)
• Plastic or synthetic fibers
• Manure from carnivorous (meat eating) animals
• Diseased plants or plants suffering from severe insect attack
• Weeds with seeds
• Invasive plants and weeds (ivy, succulents, Bermuda grass, morning glory)
• Plants that have been treated with herbicides
  Charcoal ashes
   
  Building The Compost Pile
• Locate the compost pile in a shady location out of the wind to decrease water loss through evaporation. Multiple piles are recommended for different stages of composting.
• Stockpile enough green and brown materials to make a pile that is at least one cubic yard in size. Piles smaller than 3 cubed feet will have trouble holding heat, while piles larger than 5 cubed feet will not allow enough air to reach microorganisms at the center.
• The more surface area the microorganisms have to work on, the faster the materials will decompose. Cut or bruise yard trimmings with a shovel or machete, or put them through a chipper or shredder. Some materials may be run over with a rotary lawn mower. The harder or more woody the tissues, the smaller they need to be chopped.

Alternate layers of green and brown materials. Begin with a thick layer of coarse, bulky material, such as sunflower stalks or flowers, to allow air to circulate in the pile. Next, layer greens and browns in the mix together. It is best to keep the layers thin. Continue mixing greens and browns until the pile reaches 3-4 feet high. Once the pile starts to "cook," do not add more materials.

Keep the pile moist. The compost material should be moist to the touch, but only yield a drop or two of liquid when squeezed. Moisten dry materials when adding them to the pile. A layer of straw, plastic or carpet scraps on top of the pile helps keep its outer edges moist.

Turn the pile. Ideally, the compost should cook along at 140 degrees of higher for at least three days. (Long thermometers are available to keep track of compost temperature.) When the pile cools, turn it. If a movable compost bin is being used, remove it from the pile, place it nearby, and move the compost into it with a shovel or pitchfork. If a multiple bin unit is being used, move the compost into the next bin. In several days, the pile will heat up a second time, though probably not as high the initial temperature build-up. After the pile has cooled again, it should be turned a third time. As you turn it, move any un-composted materials to the active center of the pile. Continue this process until the compost no longer heats up significantly.

When most of the bulky material has decomposed, the compost is ready. Sift large chunks out of the finished compost for further composting.

* Although food scraps can be composted, it is not recommended to add these materials to an open compost bin, as they may attract pests.