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Earthworms and Healthy Lawns


Earthworms are normally not in sight, yet they reveal their hideouts to those who look with an observing eye, or who search for signs through the soles of their feet.
Along edges of lawns, especially, are their mounds or castings visible. A close examination of these shows grass blades, leaves, and even small twigs pulled part way into their burrows. A very careful digging alongside a burrow to get to the bottom exposes plant material successfully pulled well below the surface. The earthworm does not eat these grass blades, leaves, and other plant material until they have been properly conditioned. Fungi, bacteria, protozoa, insect larvae, and other minute organisms attack these materials and slowly break them down with their digestive juices.
Thoroughly softened -- rotted, if you please -- these are taken in by the earthworm to give it nourishment. To be exact, the earthworm gets not only the decayed plant material, but the fungi, protozoa, bacteria and whatever else was feeding on these, together with some soil.
When digestion is completed, the earthworm releases the wastes as castings seen as little mounds. As one walks across a lawn, these mounds are readily felt through the soles of one's shoes as bumps. Some people object to these bumps in their lawns, and may proceed to apply arsenic or other poisons to kill the earthworms. This also kills the protozoa, bacteria, and practically all other organisms. These have been busy aerating the soil by their burrowing and other activities. The soil becomes compacted, and a variety of mechanical devices are then needed to aerate the soil and open it to water percolation.
Several years ago, over forty school lawns were walked over. Two related things were noted. On those lawns which the feet revealed had earthworms, no trace of grass cuttings could be found, even though the lawn had been cut just a day or two before. On the other hand, where there were no earthworm hummocks, grass cuttings formed dense smothering mats, or thatch, among the grass bases. In such situations, this thatch must be raked.
So, one has the option of learning the ecological fitness of the earthworm, which through centuries was building soil, or setting up a situation which is contrary to the ways of biology and ecology.

by Stanley B. Mulaik