Temperatures rising in a hot-compost pile come from the activity of numerous organisms breaking down organic matter. To keep a pile running hot, pay attention to four elements: carbon, nitrogen, water, and air.
Photo/Illustration: Scott Phillips
A hot pile requires enough high-nitrogen materials to get the pile to heat up. The ratio by volume should be 2 parts carbon to 1 part nitrogen. To aid in decomposition, keep the mixture as damp as a wrung-out sponge but not sopping wet. A variety of different-size mate rials (like twigs, stalks, straw, or hay) creates air pockets. You also increase the air/oxygen exchange every time you turn the pile.
If the pile is built correctly, it will heat up within 24 to 36 hours to the ideal temperature of 141°F to 155°F (weed seeds and disease pathogens die at these temperatures) and will maintain its temperature for several days to a week or longer. Use a compost thermometer to monitor the temperature. If the temperature starts to drop or if it gets hotter than 160°F, turn the pile again and add water. This should be done several times. A hot pile takes more effort but will produce compost more quickly—in several weeks to several months.
| 2 parts carbon
|| 1 part nitrogen
|Includes “brown” items like:
• autumn leaves
• wood chips
• shredded paper
||Includes “green” items like:
• grass clippings
• fruit and vegetable waste
• animal manure (but no pet or human waste)