Soil Sense: An Introduction to the Composting Worm

1 An Introduction to the Composting Worm

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.


With the amazing diversity of life we are blessed to have on the Osa Peninsula, one might try to determine which one (or ones) are more important to the ecosystem. Maybe the majestic jaguar, the numerous peccaries, or the towering mayo tree. Well, of course there is no one tree or even a few animals that contribute to the health and viability of any ecosystem. We thrive in a dynamic, integrated biological system that depends on ALL that diversity, from the megafauna and flora down to the tiniest invertebrates and even microscopic life supporting it. I would like to lobby for one invertebrate, the worm, as being a much bigger piece of the diversity puzzle than we give them credit for and introduce you to their special role in nature and how you can harness them to your great benefit. That’s right: the worm.

Worms come in all shapes and sizes and are found world-wide except for polar regions. There are microscopic worms, giant worms (6-7-meter earthworm from Africa) beneficial and parasitic worms, flatworms, roundworms, inchworms, tapeworms, terrestrial worms and a large number of marine and fresh water worms as well. Though fossil records are tricky for soft-bodied invertebrate animals, it is likely they were present during the Cretaceous and dinosaur age and flourished with the evolution of flowering plants.

Early evolution scientists like Charles Darwin and Jean-Baptiste Lamarck cut their zoology teeth by studying worms, and Darwin continued studying them throughout his life. Because he recognized the valuable role of worms in healthy soils, the scientist Aristotle called earthworms “the intestines of the soil.” They are the farmers of the soil and the most prolific recycler on the planet.

A more recent worm advocate was Mary Appelhof, known as ‘Worm Woman’ to her high school science students and a growing following of worm aficionados. In 1982 she wrote the book Worms Eat Our Garbage that became a primer on how to set up a home or classroom worm system. She wrote of her worm passion: “My goal, however, was not to make lots of money, but to influence people’s thinking. To get them to think differently about waste, and give them tools to deal with it.” Those of us who made it through high school biology class most likely dissected a worm, to our disgust or fascination. I was part of the latter group and drew upon Ms. Appelhof’s work when I was working as a waste reduction manager for my county in Oregon. Who knew there was a ‘Worm Champion’ out there?

The primary function of terrestrial earthworms in the natural world is in working below the surface, aiding in the healthy maintenance and feeding of the plants above. Virtually all the 10,000 species of earthworms live by feeding on decaying and rotting organic material (detritivores) and turn that waste material into the richest compost we know.

Our little earthworms perform critical tasks including:

•Aeration and loosening of the soil to reduce compaction and giving roots the space to grow.

•Cleaning the toxic by-products that plants release from natural processes and general ‘housekeeping’ of their root systems.

•In the process of working around the roots, they recycle and transfer valuable nutrients the plant requires by gobbling-up microorganisms and leaving their rich castings (worm poop) behind.

Here, and in the next couple Sol de Osa editions, we will focus on how we can employ thousands of these little workers in our own homes to transform our kitchen and food wastes into valuable rich compost. Since 58% of the waste going to the San José landfill is considered organic, worms are poised to be an excellent way to reduce solid waste.

Just a few species are considered the best food waste decomposers and are known by the names; red wigglers, common garden worm, California redworms, and tiger worm (Eisenia fetida or Eisenia andrei). There are a few other species, such as blueworms (Perionyx excavatus) which can also perform well in the tropics since they tolerate higher temperatures. The essential characteristic they have in common is that they are shallow-dwelling earthworms and so adapt well in containers or man-made worm bins. The nightcrawler or other deep-dwelling worms will not produce good results as they prefer to burrow quite deep into the ground.

The practice of using worms to treat food wastes and create compost is called vermicomposting. The compost they produce is distinguished from other forms of compost and is termed vermicomposting. When my husband, Gary, and I moved to the Osa we met many environmentally conscious people trying to manage their wastes in a responsible manner. Hearing that worms could be a viable solution, some had tried vermicomposting but ran into problems for various reasons. There are little details that must be attended to, to avoid worm calamity – horrible smells or worse, dead worms. It isn’t rocket science, but attention to them is necessary. Frustrated with available options here in Costa Rica, Gary designed a worm bin made of available hardwoods from the Osa that would serve the needs of small lodges, restaurants and schools, and then adapted the design for a smaller bin to work in a household situation. We call it The Worm Garden or Jardín de Lombrices and after almost 60 of them in use, we have a good feel for best practices, common issues and solutions and are happy to share our bit of success. The next Soil Sense article will outline how to set -up a worm bin, prepare it for worms, offer the worms a comfortable place so they want to stay, outline what to feed them (and what NOT to feed them) and the things to do and not do to be successful. You too can become a proud and capable worm farmer.


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