That's a great article because it is the first one I have read over the years that states a benefit of adding just earthworm castings to the gardening soil.
If you had a limited budget, would you prefer to add live earthworms or earthworm castings to your gardening soil ? I am not thinking about using them to start new plants, but rather to enhance the viability of the soil throughout the garden.
I can see the value of having live earthworms working in the soil. I can see the value of live earthworms in the compost bin, but so many articles talk only about adding earthworm castings.
With the ongoing drought, I know I have a smaller population of earthworms near to the top inches of the soil. I have plenty working away at deeper levels were the soil moisture is more creates a more compatible environment for them to survive.
I've noticed that the soil near the surface is far more compacted after several years of drought, but when I dig my planting holes for fall planting, I am only finding lots of earthworms down at the deeper levels of the soil.
So, I am wondering in these dry years if adding earthworm castings is the best thing I can add.