Monday, December 13, 2010

Size Counts

Fast Compost 
The retrofitting of the vegetable garden has been steaming along the acceptance has been amazing. There in lye's the the monster we have created "COMPOST" The vegetable garden alone is 1700m2. In the first bed we used approx 1m3 of compost for a 10 m2 bed  therefore we will need to make at least 170 m3 and fast .
Currently compost  comes from heaps that were made  2 to 5 months ago and are running out so I have introduced the Berkeley method.

The Berkeley Method of composting is designed so a usable compost is available sooner than standing heap piles that in reality can take up to 12 months before being able to be used. The main issue here is that we have tropical rains and the water lens is only 1-1 1/2 m  below ground level so the piles are always wet which hinders decomposition. The Berkeley Method or Fast Composting can produce a finished compost from 14 to 21 days.

Using a Compost calculator to work out our recipe as a 30 :1 ration of carbon to nitrogen is seen as most effective , we did 2 piles with different recipes and ratios to see which works best . Bearing in mind we only used materials available to us nothing brought in to the island. I had also been advised when at The Australian Permaculture Convergence (APC10) that 10% bio char added was beneficial for microbial activity as it increased surface area,moisture retention and odour absorption ... plus we all want to sequester carbon ?

All materials were shredded except for pile 2 where dry leaves were used whole. The secret to making fast compost is to shred as small as possible the carbon components, leaves, hay, straw, paper or cardboard, anything brown and dry. An increase in the surface area from shredding allows compost microbes to work better and air and moisture can circulate more effectively to the materials used.

In the past I had always layered compost piles though for this experiment all components were mixed together and looking back through my PDC notes Geoff Lawton also suggests this method, Moisture was tested by grabbing a hand full of the pile and squeezing to see if a drop of water would come out as how else do you calculate 50-60% .

Apparently size does matter so a pile at least  1 m x1m or larger and covered though not having the cover straight on the pile helps the air to circulate we used old Cudgen (coconut thatch) first with the plastic sheet on top.

Here is how we are going  
Pile 1: For a total C:N Ratio of 26:1 
Mix Used
3 wheelbarrow x wood sawdust
3 wheelbarrow x vegetable waste part composted
3 wheelbarrow green jungle mulch
0.6 of wheelbarrow bio char

Pile 2: For a total C:N Ratio of 35:1
                                                       Mix Used                                                   
3 part(s) Leaves loose-dry
3 part(s) Wood Chips Softwood
3 part(s) Leaves Fresh
1 part(s) Vegetable Waste
1 part bio char 

Day 1: Mixed

day 4

Day 4 :
Turned and added water .. both piles heated up , Pile 1 more so

Plastic sheeting placed over piles day 5

day 6 pile 1

day 6 pile 2

Day 6 : turned piles : moisture content  good handful squeezed droplet of water  Pile 1 hotter than pile 2 … both braking down though leaf in pile 2 still evident .

Day 8 : Pile 1 still hotter than pile 2 moisture good
            Pile 2 not as hot as pile 1 moisture good , leaf breaking down no smells
day 8 pile1 

day 8 pile 2

Day 10 : Pile 1 turned heat still in pile  chocolate colour  no smell

              Pile 2. More leaf break down heat still not as much as pile 1 though still breaking down to chocolate colour .. no more moisture added

Day 12  Pile 1 : temperature still very hot while doing moisture test it felt as though I burnt my   hand ,earthy   smell with signs of ants on the surface of pile

day 12 pile 1
day 12 pile 2
             Pile 2 Temperature not as hot as pile 1 which has been the same all the way through , again an earthy smell and ants on surface with more leaf decay present.

How long will it take ?????


  1. Wonderful! I also do composting but mine takes 6-8 weeks and I have limited space. I think this should be able to apply with my site.

    I would like to ask what the bio-char is? Is it a char made from wood or it is an activated carbon char? Thank you very much.

  2. Hi the bio char is from our charcoal making process by pyroloysis ovens where the carbon is locked into the bio mass used to make the charcoal, as you say activated carbon char.

    The compost making should be able to applied in most spaces as long as you have a pile of at least 1m square and observe the moisture and intial ratio of mixes and turn as suggested because every mistake puts two days on to completion. Let me know how you get on