If I want to add these to my soil, can I do it in the fall and then plant in the spring? Do I need to boil them first or do something to kill off salmonella?
Sure, you can add them in the fall and plant them in the spring. As I understand, you can add eggshells anytime...I've seen gardens where the gardener spread them around the tomato plants, right on top of the soil. I think the earthworms will munch on them a bit, but otherwise the calcium just leaches into the soil slowly.
I accumulate eggshells in a plastic bag in my freezer. When I have a bunch I crush them a bit and then sprinkle them around, or mix them into the soil depending on what else is going on in the garden at that time.
I never boil them. I think there are sufficient bacteria in the soil already to fill the niche, as it were...I'm not worried about salmonella going wild in my garden :-)
I routinely toss egg shells into my kitchen scrap pail for the worm bin without washing the egg shells. The worms like the white that is left in the eggs. I frequently see baby worms in the shelf halves.
I only wash the shells I'm saving to grind up to put in the planting holes for tomatoes, because they might get stinky otherwise.
Add to the soil,planting hole whenever you have them,washing is an option,but I don't.
Some garden wreckers like them,RACCOONS.Whenever I get lazy of forget to bury there is a penalty paid.
They are a great source of calcium for the plant,worm poop and then you when you eat the produce.great recycling.
I collect a bunch of shells and then dry them a bit in the oven so they crush up easily. Then just sprinkle around the plants. They are known to keep the slugs at bay as when they try to climb up your plants they impale themselves on the sharp shell edges...not a pretty visual but anything that keeps the slugs away is ok with me!
<They are known to keep the slugs at bay...>
In my experience, eggshells don't work worth a damn as a slug inhibitor. Slugs had absolutely no trouble crawling over the sharp eggshell pieces I set out. The only effective slug remedy I've found is iron phosphate (which is acceptable for organic gardening, and thus, acceptable for me).
I also 'em "raw" to the soil, just broken up a bit. I sometimes will crush a bunch and also add to the compost.
We add them to the compost pile without doing anything to them. They get chopped up by the tiller when DH is preparing the soil and adding compost in the spring & fall. Have never seemed to have a problem.