Could you try a drip system (small holes in the bottom of a gallon container) so that the water takes a while to get into the ground? the holes would have to be small, but it might be worth a try.

You don't use mulch? I have heavy clay and mulch makes a HUGE difference! Without it, I'd have hardpan by 100º... which is common here... mulch is a miracle for my soil.

Ditto on the mulch- not sure if that's what you're doing with the straw or not. If not- it's the best thing to keep soil from doing that!!! Holds in moisture, prevents weeds, breaks down in place to improve soil.

Well, yes, I have used lots of alfalfa hay, about a foot deep the past two years after the ground has warmed (late this year) and when my supplier can get it here(couldn't get here yet this year), and it has helped a lot..for a few things.. but my peas, potatoes and spinach(planted mid April) are stunted for some reason.. and that's in the better part of the garden.. the spinach is gone to seed right away with no leaves more than 4 inches high and an inch wide. The peas are small and tough for edible pod types. And yes I did get more soaker hoses and plan to extend the system, but it takes a lot for that water to spread .. I have tried a ditch type irrigation system, but with the hay, it's hard to see what's going on..

I think you are lucky to be able to grow the peas and spinach and potatoes in the summer! Has it been really hot there? Like in the 90's? That would do it too.

Take a good, in depth, look at your soil because it sounds as though there is simply not enough organic matter in there. These simple tests will give you a good idea of what is going on in your soil;

1)Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2. Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer you soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

Thanks for your instructions.. I will try the tests and report the results..
ps.. it hasn't been extremely hot here yet.. just a few days, and the potato plants are only about a foot high..