From: ard jonker <ard.jonker-AT-xs4all.nl>
Date: 20 Jun 2009 04:38:10 UTC   (06:38:10 AM in author's locale)
To: xtensionlist-AT-shed.com

At 18:58 -0600 19/6/09, Robert Ladle wrote:
> My
>garden can be watered pretty well with .03 in./day but never gets
>registered in XTension therefore, my water system keeps turning on
>the hose when it rains. Ugh.

I found that 10 gram of diaper super absorbers (crystals that can absorb 50x their own weight in water) loses 20 grams of water a day when left alone. This can be a very simple way of monitoring the need for garden-watering.
The diapers are designed to absorb any liquid as soon as possible, so even the tiniest of raindrop will be soaked up. The crystals wear over time, so once every year, change them or recalibrate your system. Place them in the garden in reach of your sprinkler and make sure you have excess water draining :-)
A simple pressure sensor is able to measure the weight of a diaper, or you can suspend a basket from a switch if you want very crude measurements.

ard
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