Is there any alternative to limestone

[Proud Marine Dad]

I use oyster shells in my aquaponics for buffering PH, the ammonia from the fish breaks them down much faster... but I was more referring to the calcium content.  I still think kelp is the way to go if you want both, it seems to me that anything similar to shells or bones would take far too long to break down in soil.

Oyster shell flour is available immediately. Great stuff! I have never heard of kelp being used for buffering the pH in soil but its one of the greatest amendments you can add to soil. Worm castings are also high in Ca so a lot of them is always a good thing in soil.

 

[Dave2000]

I just use moderately ground up egg shells saved over the year, but with spanish moss growing off local oak trees instead of peat.  Gotta love free. 

 

[John1234]

I just use moderately ground up egg shells saved over the year, but with spanish moss growing off local oak trees instead of peat.  Gotta love free. 

 
Hhhhhwhaat? Sounds interesting, as a potting soil ingredient or mulch?

 

[Dave2000]

^  The moss is a soil amendment I add to the container soil I reuse every year and add to a mix I put in  holes for plants in the ground.  It wouldn't be good for mulch, as it is a very delicate type of young, short moss that practically falls apart after it falls off, gets rained on and sits for a few days.  To be clear, around here it usually doesn't stay humid or rain often enough for the moss to survive long after April so it dies and falls off the trees.
 
I couldn't get a very good pic... high zoom, no tripod, wind.