From Petro's first post here…
a truly great insert from Steve Soloman, it bears repeating, imo..
"Minerals, especially phosphorus which tends to be locked up as insoluble calcium phosphate and consequently unavailable to plants, become soluble in the worm's gut, and thus available to nourish growing plants. And nitrogen, unavailably held in organic matter, is altered to soluble nitrate nitrogen.
In fact, compared to the surrounding soil, worm casts are:
-5 x as rich in nitrate nitrogen;
-2 x as rich in soluble calcium;
-contain 2.5 x times as much available magnesium;
-are 7 x as rich in available phosphorus,
and offer plants 11 x as much potassium."
WOW