Drought sends Lower Austria earthworms deep underground

Months of drought have driven many earthworms in Lower Austria deep into the soil, where they remain inactive until the ground is sufficiently wet again, ORF reports.

At a worm farm in Zwettl, around two million earthworms live in large wooden boxes, turning cattle manure, brush cuttings and grass into fertiliser. Even there, the unusually dry summer had an impact. The worms retreated to the bottom of the boxes despite regular watering, farmer Wolfgang Thaller said.

Conditions were more difficult for earthworms in fields and meadows. In many places, they withdrew from the upper layers of soil and entered a kind of summer dormancy to survive the drought. They burrow to about one metre below the surface, cluster tightly together, stop feeding and wait for moisture, farmer Gaby Thaller said.

The worms return gradually to the upper soil once it becomes sufficiently wet. A short period of rain is not enough, Thaller said. The soil must first be thoroughly saturated, after which the earthworms become active again one to two weeks later.

The prolonged drought is expected to have significantly reduced earthworm populations. Scientists at the University of Natural Resources and Life Sciences, Vienna estimate that populations in some regions may have fallen by half.

At the Zwettl farm, it takes about three months to turn the mixture of cattle manure, grass and brush cuttings into finished humus. The fertiliser can be used in flower boxes and vegetable beds, contains microorganisms that make nutrients more available to plants and can store large amounts of water.

The farm also has a small worm hotel made up of three boxes for kitchen waste. Coffee grounds, eggshells and scraps from carrots, courgettes and cucumbers can be used as food for the worms. Bananas and citrus fruit are excluded. It also takes about three months for the kitchen waste to become humus, so one box is used for fresh waste while the worms and microorganisms process the contents of the others.

To make gardens more suitable for earthworms, Thaller recommends not mowing lawns too short, using mulch and keeping flower beds as natural as possible. The more shade there is and the more material is left on the ground, she said, the more comfortable the earthworms are.