So I’m still looking for actual measurements from the WCA itself. I may just send an email to Bryant Mason and see if he can point me toward where these JADAM Measurements are.
The one thing I’ve come across is on average, you can get about 4 mg of calcium per egg shell if you ground them to a powder. So that’s a bit more useful than just saying “it’s not efficient” but I’m still unsatisfied. I don’t doubt that oyster shell is more efficient, however, I can’t argue it’s more sustainable since oyster shell is essentially mined like other minerals.
I get my oyster shells from an oyster farm, good soil amendment and great for chicken scratch (got to make them eggshells out of something)! (LOL)