“I doubt that there are many other animals which have played so important a part in the history of the world.” –Charles Darwin on earthworms
Most people know that earthworms are a sign of healthy soil. Worms process the soil, making it more tillable and creating better conditions for root development. Earthworm castings – the waste produced as they churn through the soil — are a buffet for beneficial microbes and provide nutrients that nourish roots. As soil improves and becomes richer in organic matter (think compost), the conditions become better for earthworms and the cycle of soil improvement continues.
In addition to promoting healthy soil, scientists have evidence that earthworms actually suppress soil diseases. The Connecticut Agricultural Experiment Station researched the effect of earthworms on vegetables grown in soil infested with soilborne plant pathogens. When earthworms were added to the soil, disease pathogens decreased by 50 – 70% and plant weights increased by 60 – 80% versus the control group. Though more research would be necessary to determine whether the worms directly destroyed the pathogens or if they promoted the presence of healthy microbes that populated and defended the root zone, the beneficial effect of worms on plant growth was impressive.
So how do we encourage earthworms to populate our lawns and gardens?
- Disturb the soil as little as possible, unless it is compacted. General tilling of the soil just disrupts the worms’ environment. Let them do the tilling for you.
- Keep the soil “sweet.” Worms don’t like acidic soil so amend the soil with lime, if necessary, to raise the pH. Worms also need calcium, which is usually absent from acidic soils. Your turf will do better with a higher pH as well as applying a spring or fall lime soil testing to see where it is required.
- Feed them. Worms thrive on decaying organic matter. In the urban landscape, we usually remove the leaf litter that nourishes worms. Adding compost and mulch, and leaving grass clippings, will provide them with what they need to thrive.
- Minimize the use of synthetic fertilizers and pesticides. Chemical residues will slow the buildup of the worm population. Transition to an organic-based or organic lawn care program and incorporate organic soil and PHC programs into your landscape.
Soil Care at Almstead
At Almstead, soil improvement is a top priority of our arborists and technicians who care for trees and lawns. We custom-blend top quality compost for top-dressing both lawns and plants – providing a jump-start for your soil. We also custom-blend Compost Tea, which is alive with beneficial microorganisms. Compost Tea can be applied as a drench or soil injection, so the microbes enrich the soil without disturbing it.
It’s almost impossible for earthworms to move through compacted soil. In these situations, we use an AirSpade to remove areas of compacted soil. We then backfill these trenches with rich compost. This loosens up the soil and gives a base camp for worms and beneficial organisms to gradually penetrate and improve the surrounding soil. Your arborist can measure levels of soil compaction throughout your landscape in order to formulate a plan if needed.