Soil Moisture Based On-demand Irrigation Controllers: Info & Discussion

[Az Gardener]

Late to the party but here is what I have heard from an executive at our Az Municipal Waterusers Assoc. AMWA. After being out for a few years these soil sensors to this point have not seemed to saved any water. On the contrary they tend to use more water because they are programed for plant health. Optimum plant health and water conservation at least in Phoenix are not consistent objectives. This info was given to me on the side during an event where there was some alcohol involved and was not for the general public info just yet.

I have used Acclimas on a varied site with one sensor to cover everything from loose granite to clay back fill with lawn to cacti. It was a pain but after 2-3 months we were able to get it to function OK. On another site we had two homes across the street from each other and one had the Acclima and the other had us setting the controller. We found that in general the Acclima watered a day or two before we would on an established L/S. But we are very actively monitering and adjusting our controllers so once you get the Acclimas set they were a time saver and the plants did not have to endure the stress we put them through by erring on the dry side which is our tendency. It is easier to bring something back from too dry than too wet.

Just my .02 I would like to find something cheaper though.

[Kiril]

Originally Posted by Az Gardener

On the contrary they tend to use more water because they are programed for plant health.

The sensors (the ones I am aware of) are not programmed for anything, they just sense soil moisture ... what is done with that information is up to the manager and/or the controller if using a bundled solution like Acclima. Sounds to me the Acclima is alot like the WMSL in that it tends to over water instead of underwater without user override.

IMHO, soil moisture sensing is going to give you the most accurate picture of site water use. Naturally proper sensor placement, installation, and controller management is still required. Couple that with a weather station and ET calculations and you have an extremely powerful tool for irrigation water management. Too bad there are only a handful of controllers that actually offer both, and that they are way out of the price range for most.

I also try to push my landscapes close to the PWP, so I agree that the "smart" controllers tend to over water because they are based on optimum plant health and not the minimum required to maintain aesthetic appeal. Given this is subjective observation in most cases, water use can fluctuate from site to site simply based on customer expectations.

[TRILAWNCARE]

Here is the final copy of a study done on the subject.

http://www.allianceforwaterefficienc...id&ItemID=1940