- Earthworms have an important role in helping to aerate soils, reducing compaction, improving water penetration and infiltration rates, processing organic matter and reducing thatch.
- Earthworms come to the surface under moist soil conditions (e.g. in late autumn and winter) and retreat downward in dry weather.
- However, some species of earthworms leave casts on the turf surface and this has many negative effects:
* Uneven surface levels
* Weed invasion more likely as casts may bring dormant weed seed to the surface or by wind blown seeds landing on casts and geminating.
* Mole activity increase in proportion to worm populations.
- Reduce thatch in programmed approach to minimise food source for earthworms.
- Minimal use of organic amendments.
- Lower soil surface pH to discourage earthworm activity by using acidifying fertilizers.
- Encourage drier surfaces through aeration and verticutting etc.
- Minimise amount of clippings returned to soil (organic material) by use of slow release fertilizers and/or Plant Growth Regulators.
- Using a wetting agent with strong penetrant activity will ensure that moisture moves from the surface and down the soil profile and make surface casting less likely.