We came across the use of clay pots for irrigation while doing research on water conservation done by farmers in rural communities. So here’s a description of VERY old technology.
A large clay unglazed pot is buried in the ground next to a plant. Clay is very porous, so when this pot is filled with water, is slowly leaks this water through its clay walls. The plants are planed next to the buried clay pot. The plant roots grow around the pot and suck the water.
As with our D.R.I.P.S. idea, the water is moved deep below the surface, below the evaporation layer. The top of the pot has a lid to prevent evaporation (not shown). Here’s the illustration of this basic principle:
Here’s a link to an article that gives a nice description:
[…] While clay may be available and is cheap, it doesn’t work to collect dew without glazing—the water gets sucked into the porous material and never reaches the roots of the plant. Glaze solves the problem, but the cost of adding glaze to production and the total weight of the final product makes clay a questionable choice of material. But we have thought of altering our design and placing the “cone” part directly in the ground, thus making the weight problem less of an issue after installation (still a transport problem, though). Read Nick’s post on ancient use of unglazed pots for irrigation! […]