Thanks guys. This test bed has worked really well. I didn?t want to build any more until I was satisfied with their viability. Construction is quite simple. I used a 200 litre drum that was cut in half. A jig saw is the safest way to do this. Both halves can be used if bungs are in place to ensure the beds are sealed. In the bottom of the bed you need to add an air space of some kind that will not allow sand or soil to penetrate. It will hold water. 100mm flexible drainage pipe is often twisted into a donut and used. This pipe is covered with a sock which keeps soil out but allows movement of moisture through the slots in the pipe. In this bed I used an old plastic milk crate as my air space to hold water. It was a little too high so I cut it down a bit and then rapped it in some shade cloth to make the air space. This space will eventually fill with water an act as a reservoir which will provide moisture for the plants. A pipe is connected to this air space to allow filling. The crate is then covered with course sand. The sand layer is just over half the depth of the bed. This is where the wicking occurs. The sand layer remains wet all of the time and draws moisture from the storage area. A layer of shade cloth is placed on top of the sand to prevent soil and sand from mixing. A good quality garden soil is then added to fill the bed. I added some manure, compost and a bit of perlite to my soil to make it just right for the plants. An overflow tube is added to the side of the bed just below the soil level. When the bed is filled with water, you can see water flowing out the overflow tube when the correct level is reached. The overflow tube also comes in handy during periods of heavy rain and prevents water logging of the bed. A layer of mulch is critical to prevent the bed from drying out too quickly in hot weather. When seedlings are planted into the bed, they are watered from above for a week or so until the root system is established. After that, no watering is required. During cool weather the reservoir is filled once a week but in the hotter weather it is topped up every 4 days. The soil always remains moist and plants thrive. What I like about this system is that it?s water efficient, low maintenance, and eliminates overhead watering. I want to make a couple of beds in the next few weeks before the hot weather arrives. Will post some pics of the construction as they explain the process better than the written word.
