Oyster shell flour interchangable with grit?

Hi,
It seems to be a bit of a problem to get oyster shell flour in my country, although everybody is eating oysters...
I have found oyster shell grit, which is used for chicken. Is it interchangable?

No.

Calcium carbonate should be finely ground, like flour, in order to have any appreciable affect on soil acidity. It also should be mixed/tilled into the soil rather than top dressed.

If you were to use it, you'd find that same "grit" basically unaltered in your soil years later...

Try sourcing "agricultural lime" if you're dead set on having oyster shell flour in your soil mix. It's basically the same thing (calcium carbonate). If that doesn't work out for you, I'd bet you'd have no problem sourcing dolomitic lime (Ca/Mg carbonate) in your area.

Thanks! I already have DL in my soil. It is a super soil mix. What if I buy the grit and grind it down?

You already have dolomite in your soil mix?

You don't need OSF...

Oh ok, should one put more dolomite to compensate for the OSF?
I've already eliminated the bat guano, because of environmental reasons and replaced it with a more phosphorous vermicompost. The peat moss from the base soil is also replaced with a good coco based mix.

This is the classic recipe:

• 8 – 1.5 ft3 bags of high quality base soil
• 1 – 33lb. bag of Worm Castings
• 2.5 lbs. Fish Bone Meal
• 5 lbs. High Phosphorus Bat Guano
• 5 lbs. Blood Meal
• 2.5 lbs. Bone Meal
• 3 cups. Oyster Shell
• 3 cups. Kelp Meal
• 3 cups Alfalfa Meal
• 3/4 cup Epsom Salt
• 1 cup Dolomite Lime
• 2 cups Azomite
• 2 TBS powdered Humic Acid

Don't want to comment on the recipe or your replacements. I have no practical experience with it or using coco in place SPM. You might do well to add an "aeration" amendment, as I don't see one. You have to determine how dense your soil mix is.

Try to source the "agricultural lime" in your area to replace the OSF. Calcium carbonate is calcium carbonate. I would not replace it with more dolomite.

Honest answer! Yes, the base soil has perlite and vermiculite in it, plus I will be adding about 5% innoculated biochar red wigglers and nightcrawlers.
And I have asked myself the same question about the aeration.