The last time some crazy person counted, 22,000 kinds of marine and terrestrial segmented worms shared the planet with the rest of us. Four species of terrestrial or earthworms inhabit and help maintain healthy garden soil: garden worms, long nightcrawlers, red wigglers that get stumbling drunk on kitchen scraps, and occasional manure worms whose name says it all.
Dig up one spade full of your garden soil then count the worms. You want to see 10 or more. In southern Denton County, chances are high you won’t find any, and this goes a long way toward explaining vegetable garden disappointments that commercial fertilizers cannot cure.
Earthworms live in moist, dark, coolish environments rich in decomposable composts and mulches which they munch around the clock. Ideal soil consists of about half decomposable stuff and half mineral stuff with a generous dose of water. Worms barge or gobble their way through damp, crumbly soils. Charles Darwin called them nature’s ploughs. Every 24 hours they excrete their body weight in pinhead-sized excretions and eggs called “castings.” Gardeners with big budgets buy castings in small bags at nurseries.
Castings lodge in the soil, and create miniscule spaces that fill up with water or oxygen. Plant roots, that house bacterial and fungal colonies that break down rocky soil minerals, grow into these subterranean “pores” where everybody drinks and breathes.
Worms carry on in tunnels about as wide as a pencil. Their burrows and castings can increase soil porosity up to 400%. An acre of ideal soil may contain half a million worms that, in a year’s time, can produce 100,000 pounds of castings. For the mathematically challenged that’s 50 tons of a spicy enchilada no plant can resist.
Worms, however, are living creatures that require food and water. A half pound of healthy worms can consume 3-4 pounds of food in a week. Fortunately they aren’t picky about the condition of their meals so give your garbage disposal a rest. Torn and rotten stuff is just dandy since they don’t have teeth. They like dead stuff: old leaves, twigs, wood chips, bark, animal corpses, grass clippings and straws, kitchen detritus, wild animal excrements, and water.
Keep meats, dairy products, greases, and human and household pet feces out of the garden because those items (a) create stinky gases during decomposition, and (b) harbor stubborn toxins that make people sick.
Worms are Good Time Charlies that leave the area when the food and water run out, so a gardener’s biggest challenge is to make sure the proverbial fridge is stocked. Bring on the food and drink, and it won’t take the little freeloaders long to move in with their friends and families.
In hot areas like North Central Texas, soil decomposition moves along at a faster pace than in Deadhorse, Alaska. Local soil depths decrease visibly in one growing season, and we have two. Armed with that information, local gardeners should refresh their planting areas, and feed their worms with 1-inch of new compost twice a year.