More on earthworms

In last week’s article (FW, 4 December), I looked at the three types of earthworm (epigeic, endogeic and anecic), and their differences and similarities. This week, I’ll explore in more detail the benefits that earthworms provide.

- Bill Kerr

For the farmer, the most obvious benefit is increased yield. Research in New Zealand and Tasmania in Australia is an eye-opener. When earthworms were introduced to perennial pastures that had no earthworms in the soil, crop yield increased initially by between 70% and 80%. This was followed by a long-term improvement of 25%.

In Scotland, the opposite occurred, illustrating again the value of earthworms. An invasive earthworm-eating flatworm got into pastures and crop production dropped, despite the fact that the pest did not entirely eliminate the earthworms. (One wonders how much productivity is lost in South Africa with hadedas on pastures each consuming hundreds of grams of earthworms a day!)