Features

• Earthworm casts contain undigested and digested pieces of leaf.green leaf/ leaf icon isolated image by ramzi hachicho from Fotolia.com
  
  Worm casts are fairly easy to identify. They are found on the surface of the soil. If you were to look closely, you would be able to see pieces of plant material and digested soil. Worms pass organic material through their bodies and leave casts at the top of burrows. While the burrows may not always be obvious, these casts are easy to recognize. They look like soil that is in a rounded pile that tapers to a point at the top.
  
  

Benefits

• Worms change the soil structure and allow air and water to move into the soil.closeup of dried out brown soil image by Victor B from Fotolia.com
  
  Earthworm casts have many benefits. The casts from larger worms break down organic material that falls on top of the soil. Smaller worms and microorganisms can then break down this organic material into smaller pieces and release the nutrients to plants.
  
  Worms do build new soil, but one of their main contributions is that they change the structure of existing soil. Before a worm passes through it, the soil is in flat layers. After a worm uses the soil, it is in more-rounded segments. This changes the soil structure and allows light, air and water to penetrate into the soil.
  
  

Function

• Plant roots need soil nutrients, and worms increase the availability of these nutrients.roots image by Brett Bouwer from Fotolia.com
  
  Earthworms are common in vegetable gardens, but those who love their lawns may dislike the large casts that these worms can leave behind. The casts can form blotches on a perfect lawn surface. For golfers, a cast might interrupt a great game.
  
  However, earthworms are actually very beneficial for lawns. They make nutrients available to plants, including the roots of grasses. The worms place organic matter in their burrows and on the surface of the soil. Organic material that is deposited in burrows is easily accessible by plant roots. Soil with worm casts has much more nitrogen, phosphorus and potassium than other soil, and these elements help plants grow.
  
  

Prevention/Solution

• Reduce lawn watering to reduce earthworm casts.Park Sprinkler image by Gary Ng from Fotolia.com
  
  Ironically, those who prefer an impeccable lawn without visible worm casts on the surface are not doing themselves any favors by watering in the summer time. When there is a lot of moisture instead of a summer drought, earthworms remain active in the upper part of the soil instead of migrating downward. This adds to the accumulation of worm casts on the soil surface. Reducing watering and choosing more-drought-resistant ground cover plants will reduce the accumulation of worm casts on the surface.
  
  

Warning

• Spraying to control pests can damage worm populations.locus hiding amongst the grass image by Heng kong Chen from Fotolia.com
  
  Adding pesticides to lawns and gardens has an impact on earthworm population. Earthworms may die when you apply pesticides, and while this reduces the number of surface casts, it also reduces the nutrients available to garden plants. Choose less toxic methods of pest control to help the earthworm population grow.