This is another thing that looks very interesting, and easy.
I first saw it on the Dervae family's PathToFreedom site. I can get lost in that site, anyway, it's so inspiring! Here is the link for the clay pot irrigation page http://www.pathtofreedom.com/journal/archives/2006/09/sizzling_septem.html.
They've utilized long-necked unglazed pots buried at different depths in the garden as an economical revival of an ancient form of time-release irrigation. The principle operates along the lines of a slow-release of moisture from clay pots filled with water that slowly leaches through the porous material (the unglazed clay) to the surrounding plants.
Here's a bit more on the concept: http://www.ecocomposite.org/restoration/claypot.htm
The prices of the long-necked vase-shaped pots range from about $18 to $25 and up, plus shipping. I need something more economical than that, at this point.
From the looks of things, as long as a good portion of the clay is below ground and is filled with water, the slow-release irrigation commences. The other concern is that the open top, where you pour the water in, needs to remain covered or sealed in order to prevent it becoming a mosquito farm...or stepping in it inadvertently.
Looking at different websites, there are varying heights, shapes, and sizes of pots that have been experimented with, with differing success rates. Some of these are long cylindrical clay tubes that stick out of the ground quite a way. Others are the aforementioned oblong vase-shaped ones with narrow lipped top openings which, when buried, extend only a few inches above-ground. Others are similar, but sit almost like chimeneas nearly at surface level. The simplest, though, are simply clay flowerpots.
It seems you can take a good-sized clay pot (unglazed), and plug the bottom drainage hole with something non-porous, then bury this in soil up to the under lip of the top pot rim, and then fill it with water. You're essentially putting this in an advantageous location in your raised bed or garden, where you'll surround it with plants at close proximity.
I'm guessing you then plunk a flat object on top of the water-filled pot to keep out the critters and skeeters. Then you refill it as it absorbs slowly into the surrounding ground.
The way I'm thinking of trying it would be to dig a hole where I want it to go, place it there at the correct level (snugly, no gaps in the soil around it), pour a dab of cement where the drainage hole is, and let that harden. Then fill with water, plant the surrounding area, and tuck a clay dish (the sorts they sell with pots to be set on to catch the drainoff) upside down over the top.
Then you refill when it starts getting low, I'm guessing.
The little flat area where the dish covers the hole could be weighted down a little by placing a mossy pot of herbs, a pot of trailing flowers, or a decorative shallow dish of water for birds and butterflies. Or it could just be a nice platform for a few scattered seeds for the birds...UNLESS you have the raccoon problem we do, and then that would be just inviting trouble. But a nice shallow dish of water for bird splashing would be fun to watch. The imagination's the limit.
OK, and now to try some of these things. I don't have a digital camera, but I'm going to take instamatic shots as we go and see if I can get some of these experiments off the ground. It'll spice things up here visually a tad, too, if I can post some pics.
If you've had experience with pot irrigation, I'd love to hear your tips and advice!