Thursday, December 16, 2010

A New Trick

The sandy soil was easy to dig and had no structure at all, so we could try a new trick. We went to a hardware store and bought a couple of the largest “Wheelie” bins we could find. These were dug into the soil and gravel placed in the base. Now we needed a means of showing how much water collected at the bottom of the bins. We used the 'base piece' and 'float housing' from the wetting front detectors to make a ‘riser’ to the surface. The filter screen in the base piece allowed the water into the riser. The 4 mm off-take on the base piece and tubing was used to suck water out. Then we placed a thin round stick into the float housing (where the floats normally go) so we could measure the depth of water inside – much the same as we use a ‘dipstick’ to measure the amount of oil in the car engine.

The bins were refilled with soil in the order it was removed from the hole and the drip tape went back over the top. Two couve plants were then planted in each bin. Now any water or nutrient going past the couve roots would collect at the bottom of the bin (900 mm) and could be measured accurately.

You can see the setup going in on youtube at

No comments: