Ways to improve, or "amend" your garden soil

It's a mystery, this dirt.
Your soil might be the single most important component of growing great vegetables, and yet the hardest to get a handle on. I'm still learning quite a bit about it myself, admittedly (please don't ask me what exactly 'loam' means), but this list is what I've done and what I know, and I've gotten great results.

Your Goal: good 'tilth'. Some over-simplified ways to tell you've got good tilth:
1. easy to shovel.
2. Think back when you have eaten a great muffin. You know how it crumbles? Light, airy, a little moist? Imagine a lot of those crumbs, and that's how your soil should crumble in your hands.

"Amending" just means adding stuff to your dirt to make it better dirt to grow vegetables in. Amending will get your dirt closer to our goal of great tilth. Your dirt, unless it's been a well-tended garden for a while, is probably pretty sub-optimal. There's two ways in which it can be sub-optimal: composition and fertility. I'll concentrate on composition here, because by improving composition in the ways outlined here you will increase fertility also.

Odds are your soil is either clay (in the west, where if you put a chunk on a potters wheel you could make a bowl) which is so compact that air and roots can't penetrate and water sits, or sandy, which drains of water way too quickly. Note neither of these if fluffy and crumbly like our delicious muffin! Or, your soil is just crappy in general. Ironically, if it's crappy in any of these ways, which it probably is, you should add crap.

Real crap
From cows or goats or horses or llamas or alpacas. You can get bags of cow manure at the garden store, but if you want more or have a bigger garden area, I totally suggest getting loads delivered to your house. I found a great guy on Craigslist who gets manure from farms and delivers it to my house. In order to not create an angry mob of neighbors,
-get composted crap/old crap. This is manure that has been sitting for a while, breaking down, and no longer smells. It's already starting to turn into the dirt you so desire. After tilling it in to your existing dirt, you can plant plants immediately and they will be fine.
- if you can only find fresh crap (i.e. steaming piles): buy it in the fall after your garden is done for the season. (Note: steaming piles are not ok to plant in! It'll burn your plants, and they will whither and die. That's not what we're going for here.) Dig it into your existing soil immediately - this cuts down on the smell. It will break down over winter and be wonderful for spring planting.

Worm Castings
This is earthworm poop. It's great stuff, but probably not a large-scale solution. I'd advise that you amend your soil well with other stuff listed here and the worms will quickly inhabit it, pooping in it for free forever more. I'm mentioning it here because you definitely want to see earthworms in your soil. If you don't see any, then your soil isn't even good enough for worms - and that's pretty darn sad. Amend, my friend.

Compost
Compost is broken-down leaf, grass and kitchen-waste matter. Odds are you can't make enough compost yourself to fill your garden, but if you do, go you! You can buy compost from community recyclers also. I haven't found the compost sold at garden stores to be very good, but that might just be my experience.

Amounts
For manure and compost, get enough to cover your garden by at least a few inches, although truly, I use more. If your garden needs a lot of help, I'd go up to half manure/compost and half existing dirt. Mix it in with your dirt as deep as your garden goes.


Other Amendments, in addition to the above:

Leaves
Leaves break down over winter, and "leaf mold" is a great amendment. It improves the water retention of the soil. I highly recommend raking all the leaves in fall into your garden. Water them down, and let nature take it's course over the winter.
Amount: For leaves, there's really no limit.

Straw/Hay
Not easy to come by in the city. But, straw and hay is great to mulch with, or mix in, and it breaks down slowly, ultimately enriching your soil.

Peat Moss (probably not), Gypsum(no)
What you buy as peat moss in the store is not really peat moss- it's usually sphagnum moss. While moss increases soil air/water retention which can be good, sphagnum moss is pretty expensive and thus not a suitable large-scale solution. If you find cheap peat moss, don't buy it. It's some kind of other moss that's more broken down and not as good at it's retention purposes. In addition, mosses can make your soil more acidic, so it's really not that recommended for clay soils (which are already slightly acidic).
Gypsum is sold as a way to break up clay. Don't buy it. It does this initially, but in a few months ionic forces conspire to leach important nutrients like iron, manganese, phosphorous, copper and zinc, inhibit mycorrhizal action on roots (the fungus has a symbiotic deal with roots, helping them uptake nutrients), and it's breaking-up-clay capacity peters out. Adding organic matter like compost or manure does a great job at breaking up clay and also adds nutrients rather than stripping them.



Recap:
In the fall: Mix in up to half - but usually just a few inches - compost and/or manure (either old or new). Mix in all your leaves, plus some hay/straw if you have it (or leave hay just on the top). Water. Let it sit all winter.
In the spring: if you didn't put in manure in the fall, mix in up to half - but usually just a few inches - *old*, non-stinky manure. Hay/straw can be part of your mix, or just layered on top as mulch around the plants and pathways.

I'm sure I didn't cover every possibility, but this covers what *I've* done and what has worked for *me*. (My experiences with lasagna-gardening/amending will have to be another post!). I've been mixing in lots of manure and leaves for a few years now and - not to brag, but - my plants grow so much bigger and are more productive than some of my community garden neighbors who don't amend. The difference truly is striking. I hope you can have the same great results!