Notes from Windward: #63

Earthworms and Sustainability

why vermiculture is an important part of building an ecovillage

     The key to sustainable living, at least in a climate such as the Pacific Northwest, involves the use of animals to convert things we don't want to eat into things we do want to eat or use.

     For example:
          Goats convert weeds and leaves into milk, yogurt, cheese, meat and leather.
          Ducks convert bugs and grass into eggs, meat and duck-down.
          Sheep convert grass into meat and wool.

       Leather, duck-down and wool are on that list because even though we don't eat those products, they serve to keep us warm and thereby lower the amount of food we need to produce and consume. It's a simple equation; the less load you have to put on the land, the more sustainable you are.

red wiggler worms

     A good argument can be made that the most important player in the complex, interwoven dance of sustainability is the humble earthworm. While large animals rely on plants to meet their nutritional needs, those plants rely in turn on the earthworms to meet their key nutritional needs since it's those little burrowing worms that vitalize our soil, both structurally and chemically. Without healthy, fertile soil, there's no such thing as sustainability.

     The roots of plants need oxygen in order to live. By burrowing around in the soil, earthworms open up the soil in ways which allow oxygen to get down into the root zone. Their burrows also provide channels by which rain water can sink down into the soil instead of run off down the hill. They're nature's little rototillers busily conditioning the soil structure in ways that enable plants to function effectively.

     And while their visible work is important, the invisible work they do is even more important. People often remark on the renewed vitality they see in land that has been cleared by fire. From time immemorial, people have used fire to create places to grow food.

     That burst of growth comes about because of the fire releases nutrients, such as magnesium, phosphorus and copper, which plants need in order to grow. Plants extract these elements from the soil, and concentrate them in their stems and leaves. When the fire burns the dead plant matter, those elements are released and become available for use by the next generation of plants.

note the atom of magnesium [Mg] located
right in the heart of the chlorophyll molecule

     Plants use chlorophyll to convert sunlight into sugar, and at the heart of every chlorophyll molecule is an atom of magnesium. Take a bit of green out of the garden, and you take away some magnesium. Take away enough, and the soil won't grown any green plants.

     Other than fire, the primary way that these necessary elements become accessible to the plants is through the action of earth worms. A worm is a hollow muscular tube filled with gastric juices. As dirt moves through the digestive tract, the worm's gastric juices break down organic matter in the soil in much the same way that food is broken down by the gastric juices in your stomach.

     On a household level, worms are an excellent way to quickly convert everything from banana peels to shredded newspaper into rich, fertile garden soil. On a community level, worms are a good alternative to loading up land fills with domestic waste.

     From the perspective of an ecovillage, there's an added dimension to figure in, that of how the ducks and other animals get the high-protein feed they need in order to produce useable quantities of food for the kitchen. All too often, what appears to be a sustainable practice is undergirded by some unsustainable practice somewhere back down the supply chain.

     We can grind up a quality forage such as alfalfa, and use that as the basis for producing our own feed, but that's only going to provide a protein content of around 15%. That's good enough to get by in a lot of situations, but not in others. For example, what's driving our current foray into worm production is the work we're doing on an aquaculture unit that will produce lettuce and fish for our table year-round. The produce grows in gravel beds kept moist by water from the fish tank.

aquaponic grown tilapia and vegetables

     The waste products from the fish are broken down by bacteria living in the gravel, thereby providing the nutrients which fertilize the plants. By taking up these nutrients, the plants purify the water on its way back to the fish tank.

     In a traditional hydroponics operation, you have to keep adding nutrients in order for the plants to grow, and in a traditional aquaculture operation, you have to keep filtering and processing the water so that nitrogen compounds don't accumulate and kill the fish. Aquaponics is about combining the two concepts in a way that balances out the needs of both the fish and the plants.

     Even as efficient a system as aquaponics is, it's not a free ride, and the primary input needed to make the system work is fish food. While tilapia are able to live and grow on a diet of microscopic plankton and aquatic plants, they're not going to grow very fast unless they have access to food with a higher protein content.

     Typically, fish food is in the 40% protein range, a feed quality such that fish like tilapia are able to convert about 1.2 pounds of commercial quality food into a pound of fish. Even if you have to buy your fish food, that's an impressive return.

     A sustainable ecovillage has to ask the further question of just where that extra protein is coming from. In the case of aquaculture raised salmon, that extra protein comes from "trash" fish caught in the open seas. So even when buying "farm raised" salmon, one is still consuming oceanic wildlife, albeit one step removed.

     Our current "stacked in the barn" cost for quality alfalfa is around ten cents a pound, and around seven cents for good quality hay. A hay bailing machine packs hay in sections called "flakes;" when you cut the twine on a bale, it opens up something like a loaf of sliced bread.

part of an opened bale of hay showing
how it breaks down into flakes of hay

     As a bale is broken up into flakes of hay, which are then tossed to the sheep, lots of little bits fall out of the bale and on to the ground. For the most part, these little bits are parts of leaves that have broken off of the stems. And while these little bits are too small for the sheep to gather up off the ground and enjoy, they're just right for a tilapia to nibble on.

     By breaking up a bale in such a way that the little bits aren't wasted, we can generate a lot of nutritious tilapia feed at no loss to the sheep. Pretty neat :-)

     But even super efficient fish like tilapia aren't going to prosper on just a diet of alfalfa leaves - they need additional protein in order to grow larger, and that's where the worms come in. Blend eight pounds of shredded hay with two pounds of worms, mix in some molasses as a binder, and you've got a mix that will raise a lot of fat, tasty fish.

     So, by building up our capacity to grow earthworms, we're really building up our capacity to sustainably produce high-quality, fresh food from the garden, the hen house and the fish tank.

Notes From Windward - Index - Vol. 63