Here's a simple way to water soil blocks or plants in bottomless net pots.
I cut some dried pine branches, which were about 4-5" in diameter in "wafers" about 2" thick.
Then just place the soil block on top in a seedling tray and keep a water reservoir in it.
In some of the wafers I drilled a small center hole that was then filled with dirt. This gave it more wicking capacity. It proved not necessary though. The wafers, w/o the hole, wick enough to keep the plants happy.
To automate the watering, I put a dripper into it that was connected to my irrigation system and set it to water every day for a few minutes. I cut a drainage slit in the side of the tray to just below the level of the wicking wafers, so the water level would never go up enough to directly wet the soil blocks or net pots.
Originally I was hoping to make the wafers 3" high so they would be higher than the seedling tray and then I wouldn't need to make a drainage slit. But the wafers would not wick up 3" very well. At 2" the wafers wick quite well.
It might be possible to use thicker wafers if you drill a wicking hole that is filled with the soil. I didn't try this, but might in the future.
One nice feature of this is that you can move individual soil blocks around at any time by just picking up the wafer block.