18 Day Compost


Compost is more than just getting rid of foodscraps, it is creating the possibility of life.


In a compost pile, microbial life transforms organic material and waste products into soluble plant nutrients. By making high quality compost, it is possible to recycle nutrients, add life to the soil and increase the soil fertility. It is highly recommended to combine multiple different ways of composting, thereby meeting different needs. (i.e. long term compost pile, thermophilic fast compost pile, compost toilet, earthworms,..)

Although there are many ways of composting, they all require 4 components.

  • Carbon – for energy
  • Nitrogen – for microorganism reproduction
  • Water – for habitat
  • Oxygen – for respiration (some composting requires the lack of oxygen)

One of the fastest ways of composting, this method harnesses the power of microbial bacterial to break down the organic material. The most famous example of a thermophilic compost is the Berkley 18 day compost. This method should be used when compost is required quickly. Thermophilic compost is best used for annual plants, such as in the vegetable garden or around flowers.

The advantages are:

  • Rapid decomposition
  • Kills the pathogens and weed seeds in the compost pile (pile must reach 65 degrees Celsius for 72 straight hours)
  • Volume stays the same
  • High quality compost

Carbon to Nitrogen ratio (C:N)

C:N is the ratio of the mass of Carbon to the mass of Nitrogen in a substance. Carbon-to-nitrogen ratios are an indicator for nitrogen limitation of plants and other organisms.

Desired ratio = 30:1

If ratio < 30:1

  • Excess nitrogen will be lost as ammonia gas
  • Not enough microbial growth
  • Loss of nutrients
  • Smells quite bad

If ratio > 30:1

  • Too much carbon
  • Not enough nitrogen to sustain microbial growth
  • Pile stays relatively cool
  • Pile degrades slowly (rate is determined by the available nitrogen)

Browns = High in Carbon

  • Wood ashes                      25:1
  • Shredded cardboard       350:1
  • Corn stalks                        75:1
  • Fruit waste                        35:1
  • Fallen leaves                     60:1
  • Shredded newspaper      175:1
  • Sawdust                             325:1
  • Straw                                  75:1
  • Wood chips                       400:1

Greens = High in Nitrogen

  • Alfalfa                                12:1
  • Clover                                23:1
  • Coffee grounds                12:1
  • Food waste                       20:1
  • Food scraps                      20:1
  • Garden waste                   30:1
  • Grass clippings                 20:1
  • Hay                                     25:1
  • Manures                            15:1
  • Seaweed                            19:1
  • Weeds                                30:1
  • Fish                                     7:1
  • Urine                                  1:1

How to make a 18 day Berkley Compost

Alternate 10 cm of 4" layers

  • Brown / Green / High Nitrogen
  • Tropics

    • 50% Browns
    • 40 % Greens
    • 10 % High Nitrogen
  • Temperate

    • 40% Browns
    • 40% Greens
    • 20% High Nitrogen
  • Put your food scraps in the middle
  • Flip the pile
  • Day 4 – 6 – 8 – 10 – 12 – 14 – 16 – 18

Check water content -> do squeeze test and see if you get approximately 1 drop of water

  • Inoculate with finished compost
  • Add supplements

    • Dynamic accumulators

      • Comfrey, Nettles, Dandelion, ..
    • Effective Microorganisms (EM) solution
    • Rock dust
    • Egg shells

Good luck!!

More information: http://vric.ucdavis.edu/pdf/compost_rapidcompost.pdf