Just wondering if you guys have tried the hügelkultur method, using wood logs as giant water batteries in the bottom of a raised bed, or wicking beds that have a water reservoir system contained in the bottom of the bed?
I have an elevated wicking bed that I probably only have to fill up maybe 3 or 4 times in a normal summer. Even in a drought summer, I was only filling the wicking bed maybe twice per month. I used a good mulch on the topsoil to protect the soil from the heat of the sun and to lock in that water from evaporating. I would think a wicking bed would be a great idea for drought areas and/or desert gardens.
The only thing I don't like about my elevated wicking bed is that the cost is pretty expensive for the plastic/rubber liners to hold the water reservoir. My small 2X4 foot wicking bed cost me about $80.00 in material. In comparison, my 4X4 foot 16-inch high hügelkultur pallet wood raised beds cost me about $2.00 to build.
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Almost all my outside raised garden beds use the hügelkultur method. The logs and wood in the bottom of the bed soak up and hold the water for the plants. You still have to water the hügelkultur beds, but nowhere near as much, or as often, as a regular bed which allows all the water to drain through.
I don't live in a desert, but we did have a drought summer a number of years ago. All my in-ground plants died. All my plants in the regular raised beds dried up and died. However, all my plants in the hügelkultur raised beds managed to survive and made it to harvest with maybe 60-70% of normal production. That made me a believer in the hügelkultur method and since then, all my raised garden beds use logs and wood in the bottom layer.
Of course, my wicking bed had the best results because I was able to water it as needed. I have a water gauge indicator in my wicking bed fill tube that shows me when I need to refill it. The wicking bed grew normally as if there was no drought that summer.
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Are you expecting some kind of benefit from the calcium in an eggshell to be transferred to the seedling? I don't think that will happen, due to the chemical breakdown of the eggshell which can take years for the calcium uptake process. But I would be interested to hear your results in your experiment. Good luck.
They were all showing signs of chlorosis and I thought the soil wasn't acidic enough so I kept adding more acidifier. After everything died, I got the soil tested... It had a pH of 2.9! 
I had to dig out all the soil and put in new just so I could plant other stuff. Dumb mistake but I was learning. 
