Make Compost in 18 days.

Latest Update 21th January 2021.

• I make a 280 litre batch of hot compost from 410 litres of organic waste harvested from our garden and kitchen every month.  I disperse a few hand fulls of blood and bone powder and a bag of organic cow manure through the organic waste as the compost heap is being built. This valuable animal waste helps stimulate decomposition and activates beneficial microbes.  Depending on outside temperatures, excellent compost can be made in about 18 days (see link to my Services Plan).
• This method owes its beginnings to the well known hot composting method devised by the Berkley College; University of California. 
  
• My home made compost bin makes much smaller quantities of compost than is possible by the Berkley method.  Without the artificial insulation provided by my composter the Berkley method needs at least 1000 litres of organic waste to hold the required heat as the waste decomposes.  This is not practical for me because of my limit garden space.
• By insulating my composter's wall, lid and base with 120mm thick polystyrene foam, I can hold the required temperature range of 55C to 75C in the centre of the heap whatever the outside temperature.
• Check out the link to my blogpage for build details.
• Because the decomposing microbes need oxygen to do their work, the bin's contents need to be remixed and aerated every 5 days over the composting cycle, so all of the material spends time in the hot centre of the bin.
• As well as oxygen, the decomposing microbes need a plentiful supply of water without saturating the material and forcing the oxygen out of the mix.  Maintaining the correct balance requires a little skill and experience, but the best test I know is to squeeze a handful of the material in your hand.  If water runs out of the mix it is too wet.  If the material does not hold together after you release it, its too dry.
  
• Eventually as the microbes start to run out of fuel, the compost cools. By day 18 it drops out of the highly active zone.  At this stage I coarsely sieve and transfer the compost into storage bins and leave it to mature for up to a month.  The coarse product from the sieve makes a great mulch around my perennial drip line beds.
  
• The compost will continue to decompose and is perfectly usable even if it is applied to the soil on day 18.  In practice it gets used gradually during the maturation period, just in time for the bins to become available to store the next completed batch from the composting bin.

• These two 200 litre capacity vertical bins are used to accumulate and dry the two main types of organic waste used in my composting bin.  
• The brown framed bin stores carbon rich waste like dead leaves, straw and tree clippings.  
• Half the cream framed bin's capacity is used to store nitrogen rich waste and the other half stores carbon rich waste.  This bin is lined with a light galvanised wire mesh to keep hungry rodents away from the kitchen scraps and green plant waste stored in the bin.  
• Both of these bins have wall panel infills made from heavy duty shadecloth to allow air to dry out the contents (to stop them decomposing prematurely).  When full, they contain exactly enough material to fill the composter.  I accumulate about 3 parts by volume of carbon rich waste to 1 part nitrogen rich.  
• Access to the bin's ingredients is an easy matter, just unscrew 6 Tek screws and the front panel can be removed.

• This picture shows how easily a completed batch can be accessed.  
• During the composting process, the bin is opened up like this and moved to a new location beside the original one. 
• First the lid is removed and placed on the ground to become the new base.  Then the two wall segments are separated and relocated on top of the new base.  
• They are joined together using cabin hooks, and the compost is thrown through the air from its previous location into the bin in its new position.
• Water is added (as required) during this process of re-mixing and aerating the mix. 
  
• When finished, the thermometer is replaced and the old base becomes the new lid.

• I sieve the finished compost before storing it in bottomless bins so that the compost is in contact with the ground to help attract a diverse range of beneficial soil creatures including earthworms into the compost.
  

• The composting bin has been opened up to show the layering of carbon and nitrogen rich organic waste prior to starting a batch of compost. 

• Here a batch is being transferred from its original position to the new one aerating and mixing the compost in the process.
  

• Water is added gradually as the bin is filled. 
• Note this early incarnation of the composting bin did not have a base, but in cold weather, it didn't stay in the required temperature zone long enough, so the base was added later.