Food Waste Reductions: Eggshells

In this Food Waste Reduction series I'm trying to compile all the easy ways to reduce the waste that comes out of the kitchen.

Composed of nearly all calcium, eggshells leftover from the kitchen can be a free way to help maintain nutrient levels. Adding eggshells to soil or compost boosts calcium levels, which is important because of the critical role calcium plays in hold together cell walls (calcium is used to build the middle lamella). Calcium deficiency is a direct cause of blossom end rot in tomatoes and squash.

A13ean via Wikimedia Commons (Own work).

I had to use this photo because I don't have 

blossom end rot,...b/c I put eggshells in my soils.

*********************************************************************************

Eggshells can also be used in the garden to help fight off crawling pests, e.g. slugs and snails. Crushed eggshells works much like diatomaceous earth on these pests, causing fissures in their soft tissue that lead to fatal dehydration.

In order to cycle the shells for the garden I save them as I use the eggs, keeping them in the freezer until I have a full batch worth prepping. Saving them in the freezer is another good repurposing use for those tupperware-ish food containers that can accumulate.

1. Wash them off to remove all of the membrane. It's easiest to wash them as you save them. After breaking open eggs just hold the shells under water and use your fingers to rub and rinse off the insides of the shells.  Removing the membrane helps adhere to composting basics by reducing the amount of food waste that can attract mammals. That membrane being made of lipids also is not something that would generally go into compost because it slows down decomposition rates (because it is hydrophobic). Rinsing also helps reduce the risk of transmitting salmonella. 
2. Toast the shells by evenly on a cookie sheet or oven pan and toast them in a toaster oven (you can even stick them in an oven that has already been heated to roast or bake and has been turned off). You can also bake at 200°F for approximately 30 minutes to completely eradicate any salmonella concerns.
3. Crush them with hands or a rolling pin. You can also put them in a food processor for really fine grinding although that may be rough on your processor blades. Some people prefer to crush the shells before toasting to decrease toasting time. I crush them either as I put them in the freezer of after they're toasted because they crush mush more easily once the membrane residue is baked and the shells become more fragile.

When they come out of the oven they'll crackle very nicely:

https://soundcloud.com/k-frye/eggshells-crackling

.


The crushed shells can go into the compost or soil. If using directly in a garden bed for a calcium amendment, be sure to know that it takes a while for the shells to decompose despite the crushing and toasting. The full effects of your added calcium may be realized next year, so in the Midwest as we close up our outdoor gardens remember this is a great time of year to add those eggshells for next spring's growing season.