A Basic Guide to Hot Composting
Introduction
“Hot composting” is a method where microbial activity is used to process a compost pile in a short amount of time. Hot composting is great to produce large amounts of compost at a time and promotes plant growth (provides plants with nutrients and helps improve water retention) when assimilated into the earth. Although this process requires specific equipment, it is one of the more time-efficient composting methods. You can either use a wire fence bin, put the materials in a pile, or even make your own bin out of wood or shipping pallets.
Preparing a Compost Pile
An ideal compost pile size is around four by four feet. This size is manageable, yet effective since smaller piles tend to not heat up sufficiently.
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Before starting the compost pile, try your best to collect all of the materials you plan to compost on hand since the goal is to get the pile to heat up. But don’t worry if you do not have all of your ingredients, since this method requires you to turn the pile regularly. Therefore, you will get the opportunity to add some more materials to the pile.
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Before forming your pile, install a metal stake in the middle of your pile to use as a heat gauge you can touch with your hand. You can also wiggle it to aerate the compost. A rake can also be used instead since it allows you to easily mix and turn compost piles.
Hot Composting Pile Materials
For hot composting, your pile should include approximately this ratio of organic matter:
30 parts carbon, including “brown” items such as:
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Fall leaves
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Wood chips
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Straw
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Dry corn stalks
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Shredded paper
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Small twigs
1 part nitrogen, including “green” items such as:
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Grass clippings
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Animal manure (but no pet or human waste)
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Fruit and vegetable scraps
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Weeds that haven't gone to seed
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Deadheads/trimmings from garden plants
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Coffee grounds and tea bags
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Water
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Air
Regardless of the materials used, cut them into smaller pieces to break the content down as quickly as possible. One possible approach to this is to run a lawnmower over the materials to shop it up.
Procedure
Completely mix the ingredients and form a pile. Then water the pile heavily to moisten the ingredients (to the extent where a bit of water comes out of the sides of the pile), and then let it sit. Try to avoid simply layering compost, as this can make the process take longer.
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The compost pile should be placed outside in the sun if possible since the shade will cool down the compost and slow down the process.
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Two factors to hot composting success are monitoring:
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Soil temperature
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Soil moisture
The ideal microbial activity temperature is 130-140°F (55-63°C), where the microbes break down the ingredients and reproduce the most rapidly. This temperature range also helps kill most weed seeds and harmful bacteria within the pile. The soil temperature can be measured by using a soil/compost thermometer or touching the pile with your hands. If you cannot keep your fist in the pile for more than a few seconds, the compost is at its optimal temperature range. Ash-like remains on plant material can also indicate your compost pile is processing successfully.
When the pile cools down to less than 130°F degrees, turn the pile. This typically occurs every 2-3 days. Turning the pile aerates the materials, stimulating the microbial activity again.
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Make sure to also monitor the moisture of your compost pile. The materials in your compost pile should feel like a wrung-out sponge.
Your Compost Too Dry?
Microbial activity will decrease in the pile.
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To fix this, water the pile all the way through with a hose.
Your Compost Too Wet?
The microbes that work in anaerobic conditions will process your pile instead of the intended microbes.
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To fix this, turn the pile and add a high-carbon ingredient (ie. shredded newspaper) to soak up excess moisture.
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If the rain is causing the pile to become too moist, simply cover the top with a tarp.
After following this routine for about three weeks, your pile should have transformed into dark brown, crumbly compost. You can now add this to your garden or lawn.