Well, 6.5 is about perfection for the mostest crops so I'd be careful with any wholesale acidifications. Unless you are primarily interested in growing potatoes and berries.

I think yes, in the ground is more drought-proof than in containers. Your conditions indicate loosening the ground deeply to allow moisture absorption, adding OM whether it be rotted manure/hay, compost, or what-have-you, and using deep mulch on established plants. When seedlings are tiny you could maintain a dirt-mulch which is very helpful in dry conditions.

Question: how much space do you have?

If the answer is quite a bit, then Steve Solomon is probably your next step. His books are arguably the finest resources for those trying to run a dry garden. The key is giving each plant enough space to grow their roots and find their own water.

As for the alluminum sulfate, I would hesitate to use this stuff without a) a proper soil test (that would be a professional test, not a Home Depot ph kit) and b) awareness that exposing yourself to increased levels of alluminum may be detrimental to your long-term health. You are better off with elemental sulfur. It acts more slowly, but is much safer.

Raised beds are the way to go. And unless there is good reason to use the tiller (i.e. breaking up sod or large tangles of weeds), you may consider doing the "old fashioned" way using hand tools. Again, depends on the area involved.

Soil additives really depends on your soil test results. Without a specific profile, adding anything to the soil could do much more harm then good. For instance, I had purchased all the ingredients for a complete organic fertilizer prior to my soil test. The results indicated high organic matter (14.5%), magnesium deficiency and a ph of 7.8. Suffice it to say that had I added the compost, lime and bone meal that I had planned on adding, I would have done some serious damage to the soil balance.

In other words, get a soil test, now.

Best of luck,
Michael

Here is a link that might be useful: Steve Solomon: Gardening When It Counts

have you considered no-dig raised gardens? no formal sides needed take a look at our pic's see how we do it, might be some clues there as well?

len

Here is a link that might be useful: lens garden page

From what responses, it looks like I should skip tilling and using the natural soil? It seems raised beds have a lot of advantages. I have access to a nice tiller though waiting to be used.

What kind of container are you growing corn in? Do you have enough stalks for x-pollination?

I have about 10 stalks today. Growing 2-3 per 5gal container all next to each other.