As far as I know, the point of using bottles is as a cheap replacement of drip irrigation, where instead of supplying water through a pipe, it is just filling the bottle. If the irrigation is done under the surface, even less water is lost by evaporation. Plastic bottles degrade when exposed to sun and heat, though, and once they are empty, they can be easily taken away by the wind. So you either bury the bottle or stick it in place with something.
An idea: Cut the
thread of several bottles, then cut them in half vertically, and make a few tiny holes on them all. Then, dig a ditch with a small slope, maybe one feet deep. Place the bottles on the ditch, in a way that they can retain water, and spill the excess water down the slope into the next half bottle, cascade style. Test it: Pour some water over the first bottle, and watch the water cascading to the last bottle. Have a small pipe reach the first bottle. Does it work? Fine, then bury it again with good structured soil (maybe use some potting soil). When you want to irrigate, make a small stream of water go through the pipe, slowly. The soil in the half bottles will become wet, and it will slowly release water down through the holes and some will percolate to the adjacent soil.
This system looks good for row gardens.
There might be a risk of creating anaerobic conditions if the water longs too much to percolate, so checking the level of moisture before irrigating is a must.
3
