Shovel It

And yes we all know what "it" is and around here, it's gonna come from a cow, a horse, or a chicken.  Anything else either isn't commonly raised or it's not so good for gardens.  And to have access to this kind of compost, you'll need to first make friends with a livestock farmer, obtain a good shovel, and have access to a truck.  And then have access to a really great shower.

The most important thing to remember when using manure in your garden is that it also needs to be composted.  Fresh manure is high in nitrogen, which "burns" garden plants and can kill them.  The natural processes that occur when manure is composted, aged, or seasoned reduces the amount of nitrogen and makes it very suitable for digging into your soil or spreading on top of your garden.  Manure should be composted at least a month, and longer is better.  If you're going to be growing root crops like parsnips and carrots, you'll want to use manure that has been composted for closer to a year as fresher manure stimulates root crops to fork as they grow instead of producing one strong root.

Chicken manure is the "strongest" of these three, followed by cow manure and then horse.  Horse manure can almost be worked into your garden immediately, but if you have a chance to let it age, that's still helpful.  Horse manure especially is often mixed in with wood chips and so composting helps the chips and manure break down into a more usable texture.  All manures are likely going to include a  good many weed seeds, and composting helps these either break down or sprout and die so that the seeds aren't as much of a problem in your garden.

If you have pets, don't consider their litter to be manure.  Unless you have rabbits - rabbit manure is just fine.  But don't shovel dog litter into your garden or compost pile, and don't dump your cat's litter box into it either.  Just don't.