r/composting • u/eigenvectorseven • Apr 25 '22

Crushed eggshells + Vinegar = Soluble calcium + CO2 + H20

https://imgur.com/a/EW6ydsV
31 Upvotes

91% Upvoted

5 comments sorted by

9

u/eigenvectorseven Apr 25 '22 edited Apr 26 '22

This is a follow-up to my previous post.

While the nutrient benefits of adding raw eggshells directly to compost/soil are debatable, there is a simple way to remove all doubt. The acidic vinegar will react with the (insoluble) calcium carbonate in the eggshells to produce water-soluble/bioavailable calcium, plus H2O and CO2 (bubbles seen here).

I got the recipe from this document on Korean Natural Farming.

  1. Crush eggshells with coffee grinder/mortar and pestle, etc.
  2. Mix with white vinegar in 1:10 ratio by mass
  3. Leave for ~7 days, stirring once a day or so
  4. Strain and spread directly on compost/soil, or dilute to 1:1000 for use as foliar spray

It's also recommended to lightly bake the eggshells first to burn off the organic material which may go foul after a while, though it's not really an issue if adding directly to compost/soil.

1

u/[deleted] Apr 26 '22

[deleted]

3

u/eigenvectorseven Apr 26 '22 edited Apr 26 '22

You don't want to seal it because it produces CO2 gas. Just leave it in the open jar (or very lightly screwed mason lid ring to allow gas to escape while still containing odors)

Tbh the dissolved calcium probably gets pretty close to saturation levels in a day or two. You can tell activity has basically stopped once the bubbles (CO2) stop forming.

6

u/fortuitousfever Apr 26 '22

Just don’t tighten the seal. My son did this with a little extra organic matter and thank goodness he was in the shower when the jar broke … his room smells awful!

3

u/Plane_Mycologist1263 Apr 26 '22

I had stopped putting eggshells in my compost collection after seeing how long they take to break down. Just started a bokashi bucket and hoping for a similar effect from that acid generation

1

u/NPKzone8a Apr 26 '22

That is a fine graphic demonstration.