Drought could halve earthworm populations, BOKU expert warns

Extreme and prolonged drought could reduce earthworm populations by up to 50 percent, according to agronomist Pia Euteneuer of the University of Natural Resources and Life Sciences Vienna, known as BOKU, as reported by ORF.

At a BOKU trial field in Raasdorf in the Gänserndorf district, Euteneuer found that earthworms had disappeared from the upper layers of the dry, hardened soil. A ploughed field that contained about 100 earthworms per square metre in spring had none during the latest inspection, she said.

The worms retreat into deeper soil layers to avoid drying out. They curl up, stop feeding and remain still while waiting for rain, Euteneuer explained. Months without food or water could cause the population to fall by up to half, she estimated.

The decline could also have longer-term consequences for agricultural yields. Euteneuer cited a global study showing that earthworms contribute to between 6 and 10 percent of wheat yields.

Earthworms loosen soil, improve its ability to absorb water, support humus formation and help plants access nutrients. The trial field showed that plots using direct seeding, without ploughing, were more resistant to drought than ploughed fields. Euteneuer said the method encourages earthworms, which then loosen the soil themselves, while also reducing soil erosion without lowering yields.

However, she said the lack of rain is currently affecting all parts of the environment, not only earthworms.