Soil Sense

1 How to Make Your Own Compost
By Terri Petersen and Gary Strehlow

Terri Peterson and Gary Strehlow own Nueva Tierra de Osa and make their composts, Worm Gardens, and other organic products in the shade of their 17 hectares of rain forest in Los Pargos. They also offer school and community programs and on-site and remote compost consulting services. Tico Pet Veterinary offers some of their products in Puerto Jimenez. They can be reached at and welcome visitors to their small operation.



Compost is a living thing! It is full of billions of microorganisms and visible organisms that participate in the process of decomposing your organic waste.  When we are making a compost pile, we can think of it as an Invertebrate Zoo teeming with life.  The inhabitants need the same things as all living creatures:  water, oxygen, food and a home.  If we construct their home well and provide the food, air and water they require to thrive, we will have wonderful, completely decomposed material as a result.

Although there are many different kinds of soil amendments made with organic materials and supplements, here we are describing the basic steps to make thermal compost from the wastes you have around your home or finca.  Thermal compost results from a process that heats up due to the activity of the microorganisms (not due to the sun) and, if done properly, does not require any additional products or supplements to accomplish.  This is nature’s decomposition, just speeded up.  Just follow these steps.

  1. Create your compost bin or area

Each compost pile needs to be at least 1 meter x 1 meter x 1 meter to generate the mass of organisms that will do the work.  It is best to contain the materials inside some form of a 3-dimensional structure to maintain the shape and retain moisture. This can be anything from dry-stacked cement blocks to a wood-sided box, bamboo poles, or even bales of grass built up as ‘walls’ of the bin. There are many designs for making compost bin housing.  Search the web for the option that is best for you.  Just remember that natural material will also decompose and will need to be replaced and/or repaired frequently. The basic process is the same no matter the structure of the bin. Build at least two bins, side-by-side to facilitate the turning process (described below). Three bins are even better.

Roofed structure covering compost piles

  1. Compost bin placement

Situate compost bins where most convenient for easy access.  This can be inin either a sunny or shaded place and since Osa rainfall is measured in meters, the bins should be under cover of a roof.  They MUST be placed on dirt, sand, or grass and not on cement, rock, or ceramic. The microorganisms that will do the decomposition for you will enter and leave via the ground below.  Having it on dirt allows them to do so when it is most appropriate.

We recommend that you place your bin near where you generate yard waste (i.e. yard or garden) and near a water source (within the distance of a hose) as you will need to wet your compost at various times in the process; hauling water in buckets gets old – QUICK!.

Nueva Tierra composting site

  1. Gather your materials into BIG piles and divide them into two categories:

BROWN:  These are dry, high-carbon content materials and may include:  1) Dried leaves from trees or bushes; 2) Thin woody branches and twigs; 3) Dried grass or other plant material; 4) Newspaper; 5) Paper towels; 6) Paper egg cartons; and 7) Paperboard boxes (i.e. cereal boxes).  Do NOT use corrugated cardboard because it has a lot of glues in it.


Mostly food waste, high-nitrogen materials and may include:  1) Green grass; 2) Plant trimmings; 3) Dead flowers; 4) Fallen fruit; and 5) Food wastes in small amounts, including coffee grounds.  Do NOT use meat or fatty food waste, and  go light on citrus.


  1. Build your compost pile.

Watering compost pileUsing the collected materials begin by making a layer of brown materials about 3-4 inches deep on the floor of the compost bin.  Wet this layer thoroughly with your garden hose.  Add a 3-4 inch layer of green materials and wet it well.  Continue to build your pile inside the bin exactly like this until it is completely full.  You’re making a lasagna of yard waste. Don’t forget to water each layer as you go.


  • Every few layers, add a shovel full of good soil or compost to add beneficial microorganisms to the process;
  • If you can cut or mulch up the materials they will decompose much faster; and
  • If you use small branches or stems, make sure they are chopped up well
  1. Managing the pile

Once the compost bin is full, wait at least one week and then turn the contents of the pile with a pitchfork (one of the few tools we recommend having) and transfer everything from the full  bin to the empty one alongside.  Wait another week and repeat the process of turning the pile, this time back to the first, now empty bin.  Turn the contents 5-6 times or until the materials cease to look like the original components. Then let it rest—untouched—for one month.

Newly made compost pile


  • During the first 6 weeks of maintenance and each time after you have turned the pile, the materials should heat up over a few days to at least 38⁰C but not beyond than 60⁰C. The heat is not from the the sun but from the activity of the microbes in the compost pile.  After a week, the temperature will drop back to ambient temperature, and it is time to turn the pile again to start-up the heating process once more. If you do not turn your piles, it can take a year or more for the composting process to complete.  But by regular turning, your compost will be ready in ten weeks!
  • If you notice that any portion of the compost of the materials is very dry (sounds crispy when turning) then add water to the dry area.
  • If you notice an ammonia smell, there may be too much of the green material in the bin. Add more brown material to this part of the pile.
  • The one-month resting period is important to allow the final organisms (worms, insects and other microorganisms) the time to finish the compost. This period will stabilize the compost and add valuable beneficial nutrients.

Get Started! You are doing a great thing for your garden, your
health, your community and the Planet!  In next edition’s Soil Sense we will expand on composting hints and provide troubleshooting tips and suggest uses for the good compost your are making.

Wood compost bin structure

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