I posted this info under the "Question about soil", but wanted to make sure it got wide readership, so I am reposting it. I am wondering if anyone else is doing any kind of pseudo-scientific (some controls added to the "experiment") comparisons of soil, bed heights, or other variables?

In Dallas, TX, I had four SFGs (4'x16') last fall, and have been growing this spring. Each bed was identical in terms of what was planted in it and they were all in a 340 square foot area. I wanted to experiment with 4 different soil mixes, because my previous gardening experience told me Mel's mix just wouldn't work in the Texas heat and drought, but I was prepared to be pleasantly surprised.

I have access to a landscape wholesaler, so one bed was EXACTLY like Mel said to make it, complete with the landscape fabric bottom, 5 kinds of compost, peat, and #3 vermiculite. Comments/Results: Almost no weeds, Very expensive, Skimpy growth, harvest approx 2/3 that of the top-producing bed. Twice-daily waterings needed, fertilizer boosts needed, fire-ant prone bed. Upon inspection at the end of the season, plants had a much smaller root system. I took the bottom off at the end of the first growing season and am just growing in the newly-amended mix, on top of native soil, this spring.

One bed was a mix of native soil and composted leaves, rototilled to perfection. Comments/Results: This was the weediest bed (including nut sedge, which went absolutely CRAZY in this bed!). It also, at the end of the first season, had the least friable soil, and was badly in need of a BUNCH more organic material. It was #3 in terms of water usage and amount of veggies harvested. It was probably 75% of the top-producing bed.

One bed was a mix of native soil and composted leaves, rototilled (to function as a "double-digging"). A layer of corrugated cardboard was then laid down, watered, and 3" of specialty landscaper mix (from Living Earth Technology Co. in Dallas) was added. This mix consisted of green sand, lava sand, composted pine bark mulch, soil, and compost. I also added an additional 3" of compost and mixed the compost and specialty landscaper mix together, and dumped them into the bed. This bed was #2 in terms of water usage, #2 in terms of crop production, and there were no weeds to speak of.

The native soil in the last bed was covered with a layer of corrugated cardboard, watered, and then filled and tilled with 4" of Living Earth's specialty landscaper mix, 2" of compost, and 1/2" of expanded shale (also from LETCO). Expanded shale is a relatively new product, and even though I am an Aggie, and A&M was endorsing its use, I was skeptical. I didn't want "gravel" in my veggie garden! I was WRONG!! That stuff is amazing. It holds water SOOO much better than vermiculite! And the plants seem to respond to it better than they respond to those little water crystal things. I only had to water this bed twice a week during the summer, on average (I spot-watered the tomatoes water every-other-day), and that was a miracle! This spring, the other 3 beds had lost about 2" of height; I presume that is the organic matter breaking down. This spring, this bed lost about 1" of height, but the soil looked better than any of the other soil, and had more worms in it.

I had such great luck last summer/fall with bed #4 that this spring, I boosted all the other beds with compost AND expanded shale. Then, I added kelp meal, dry molasses, and Soil Alive! from Gardens Alive to each bed, and everything is growing like gangbusters.

I am not an employee of Living Earth Technology, and I did not get paid for this. However, I would recommend anyone in Texas, who is close to them, just buy your specialty landscape mix and expanded shale from them and be done with it!