Berkeley Hot Method

Sacha May 18, 2021

For home composting, the University of California, Berkeley developed the quickest method. Naturally, the compost pile can become as hot as between 55~65 ℃. If you do it right, your garden compost should be ready in 18 days. 

Berkeley Hot Composting Method takes effort to set up and run. But it finishes compost in 14 days also pathogen-free
Berkeley Hot Composting

In short, you scavenge compostable matter, sort them into carbon-rich and nitrogen-rich ingredients (See this table). Chopped everything into 10-12 cm pieces. Mix two ingredients in the ratio of 3 : 1 (Carbon: Nitrogen) by volume. Your compost heap needs to be as huge as 1 cubic meter to retain the heat. After you set up, you need to turn the pile once in 3 days. In 18 days, your compost will be ready.  

Let's look at the pros and cons of this method:

Pros: 

  1. It’s quick. It only takes 18 days for the compost to be ready to use. 

  2. The only technique required is turning the pile. 

  3. No equipment required, but a compost thermometer is highly recommended. 

Cons:

  1. An outside space of 1m*1m*1.5m is the minimum required.  

  2. Turning every 3 days can be laborious. 

  3. You need to have enough materials to start a compost heap, either by storing or scavenging. 

  4. Everything needs to be chopped down to 10-12 cm pieces.  

  5. You shouldn’t add your daily kitchen waste after the pile is set up because bacteria need to work through three phrases. This is inconvenient for people who cook and generate food scraps everyday. It means that they need to store the food wastes in a freezer for compost. 

  6. You shouldn't add meat, fish and dairy products in the open composting pile for they will attract animals and flies. 


 


Step by step:

  1. Chopping or shredding the organic materials into 10~12cm pieces to increase the surface area.

  2. A thorough blending of the carbonaceous and nitrogenous materials and activators*, make a pile at least 1m(Long)*1m(Wide)*1.5m(High)

  3. Spray some water with a garden hose to the level where the pile is not dripping water.

  4. Start turning the pile from outside to inside on the 3rd day. Then turn it every 3 days.  

  5. In 18 days, the compost is ready to use. 

*The activator is a nitrogen-rich substance, for example, manure or human urine.

When you set up a Berkeley Hot Composting pile, it has to be 1 cubic meter large and also the carbon to nitrogen ratio is 3:1

Notes:

  1. The ratio of the carbonaceous and nitrogenous materials should be close to 30:1, which means for each 30kg carbonaceous material, you need to mix with 1 kg nitrogenous materials. 

  2. This hot method decomposes quickly. You can even use paper and dry garden debris as carbonaceous materials. 

  3. The pile needs to be at least 1m*1m*1.5m to retain the heat. For colder areas, it needs to be bigger. 

  4. Turning is essential, make sure you turn the outside layer in, top layer down. 

  5. The carbon to nitrogen ratio doesn’t have to be exact. Just try to be close. 

  6. If you have a compost thermometer, take your temperature every day can tell you if the composting pile is going right. Normally the temperature should show the trend below. 


    At the beginning of composting, it's the mesophilic bacteria who work at 10~40 degree Celsius, when the pile gets hotter, reaching 40 degrees, thermophilic bacteria will take over and decompose faster, so the temperature of the pile will raise up to 70 degrees. Just by taking the temperature of the pile, you know if the pile is working properly.
    If you monitor daily temperature of your compost pile, you should see temperature showing a trend like this

 


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