This was really interesting. I've always known about how earthworms aerated the soil and their slime helps to bind soil particles together, but never knew the details of how it all worked.
It says that earthworms eat microbes and that the bacteria in their intestines help to break down the organic matter they digest so they can absorb the nutrients from it. Now, my question is, are these the same bacteria that were eaten or are they a dedicated type that resides in the intestines? Also, what happens to the bacteria that are eaten? Do they survive or are they killed and their nutrients taken up. I'm inclined to think that at least some of them survive since on page 99 in says that bacteria and fungi are bound in the fecal pellets that deposited.
The details on page 98 about the vermicastings being extremely high in plant-available (mineralization?) nutrients made me remember about an experiment that was posted in the Tomato Forum.
I believe it was Duh_Vinci who tested various soil mixes by starting tomato seedlings in them. They all performed about the same, except for the one with worm casting which produced noticeably hardier seedlings. Reading this, it's no wonder since not only did it have large amounts of plant-available nutrients, but also bacteria and fungi built right in! Now that's what I call a soil amendment.
Page 99 indicates that an overly high earthworm population can adversely affect microbial populations by direct consumption of the microbes and of their food source. So, it seems to say that you can have too much of a good thing. However, on page 101, it condemns soil practices that kill earthworms.
So, can you really have too many earthworms, and if so, how do we keep that from happening. Perhaps the negative affects of too many earthworms are in a nature system. I think that if we continually add organic matter (and, as a result, microbes) to a garden there will be enough to go around for everyone and there will be no need to worry about too many earthworms. Perhaps this will be touched on later in the book.
A great insight into the many benefits of earthworms, none the less.....makes me want to start a vermicompost bin