For those who like their lawn or golf course tidy, Earthworms can create disruption and maintenance problems. The worm castings are faecal matter deposited on the soil surface. It is important to remember that earthworms do not feed on green grass and are therefore not a pest.
Earth worms need moisture and organic matter, therefore moisture content of the soil will influence worm activity. Constant or regular irrigation of turf will keep the top soil in a state of moisture that suits the worm. Letting the soil dry out between irrigation will drive the worm deeper into the soil.
Researches have shown that “collecting clippings consistently reduced the rate of casting by nearly 30 per cent over the whole year compared to the areas where clippings were not removed” (Baker 2002). For residential turf mowing, a higher setting may hide castings.
The benefit of earthworms outweighs the perceived negative impact. They feed on micro-organisms, contribute to the mixing and movement of nutrients, decomposition of organic matter, improve aeration and increase water penetration.
Birds, amphibians, ants and centipedes are the natural predators of earthworms. Applying pesticide to control earthworms will affect their predators and may result in a cascade of unforeseen consequences. In the USA, golf courses use an organic fertiliser that contains plant saponin to control earthworms. Plant saponin has a low acute oral and dermal toxicity for vertebrates, including mammals and birds (Sparg, S. G., M. E. Light, and J. V. Staden. 2004). High concentrations of saponins are toxic to fish.
About Patrick Regnault
I have worked in the horticultural and landscaping industry for over 35 years in three different countries.I am a member and Registered Horticulturist with the Australian Institute of Horticulture and member of the Housing Industry Association. I am the owner of Interactive Landscapes, a successful structural landscaping and landscape design business. I believe that what gardens and gardening do is to reconnect people with the fundamental elements of nature. A good gardener will try and acquire a profound understanding of the balance of nature and endeavour to do the best to improve the environment in which the garden is situated. At Interactive Landscapes it is a philosophy that we put into practice when designing and creating a garden, no matter the size. Our name reflects this as we understand that gardens are a place of interaction. View all posts by this author »