Stimulate microbial activity. Although earthworms derive their nutrition from microorganisms, many more microorganisms are present in their feces or casts than in the organic matter that they consume. As organic matter passes through their intestines, it is fragmented and inoculated with microorganisms. Increased microbial activity facilitates the cycling of nutrients from organic matter and their conversion into forms readily taken up by plants.
(
gronkpan https://twitter.com/VomitingLarry,
Thu 30 Aug 2007, 11:44,
archived)
Provide channels for root growth. The channels made by deep-burrowing earthworms are lined with readily available nutrients and make it easier for roots to penetrate deep into the soil.
( gronkpan https://twitter.com/VomitingLarry,
Thu 30 Aug 2007, 11:47,
archived)