HOW TO PROTECT THE THINGS YOU CACHE
Anything can be cached. Consider that in order to protect his air force from destruction, Saddam Hussein buried entire airplanes. Basically, you can bury anything. There are some basic rules you need to follow, and there are some preservation tips you need to be aware of:
Moisture is your biggest enemy: Overwhelmingly, moisture will be the single biggest factor you need to protect your items from. Moisture can ruin foods, corrode ammunition, damage firearm internal parts, and kill sensitive electronics such as radios and flash drives. Of all the considerations you account for, moisture should be at the top of your list to combat. Keep in mind that some items are not affected by moisture, but there is no reason to purposely allow moisture in your cache even if the items are impervious to it. Gold and silver bullion, for example, is fundamentally unaffected by moisture. Gold coins on the ocean floor have survived for hundreds of years intact. Still, why bother dealing with a soggy, watery mess if you can avoid it in the first place.