A few years ago while building a new home out here I didn't have time for a new garden so we used 16bales of straw total with two rows of 8 each. I dug about a 6in deep trench and set them in there. Put composted chicken and horse manures about 4in deep on all the top. Started fertilizing with fish emulsion about two weeks prior to planting, at planting time I used about two bags of cheap potting soil to cover the top and planted the seeds in it. Onions and Chard loved it. Some Okra, but not as tall or productive. Tomatoes not as tall or productive, but good overall. We did manage a couple of pumpkins on the end bale about 12in diameter. At the end of the season the bales were about decayed away. Our summers are very hot and this may have been why. Beats not having fresh veggies all summer, but prefer using a garden.
