[I received an email referring to your post about Canberra this morning, but can’t find it in the Forum? the link in the email doesn’t link to anything?]
I don’t have a rain monitor, I check the rain forecast in the morning and set a rain delay if there is >60% chance of more than 10mm, for as many days forecast. Most of my system is garden drippers with only one in-lawn sprinkler system which runs at 10pm at night once a fortnight. I aim is to water consistently, and only enough to stop the plants dying completely.
I’ve been away from home for a few days and discovered my system had not enjoyed the recent upgrade, the phone app showed the weather report was in imperial and watering on 140% after 7mm rain last night.
Canberra rainfall: http://www.bom.gov.au/products/IDN60903/IDN60903.94926.shtml
I went into the app settings and reset it to metric and the watering percent dropped to 72%. I haven’t updated the firmware yet so will try that and see what’s going on.
You can check the recent Canberra Airport Evapotranspiration here:
It’s computed once a day at a particular time, whereas I think the OS WeatherApp algorithm calculates it instantaneously as it’s about to run a schedule. You can’t easily compare the two as ETo is not recorded in the OS unit’s logs.
Having said that, if you chart the recent Canberra Airport evapotranspiration above, it doesn’t appear to change that much with rain, see attachment. Perhaps because we get so little rain and the evaporation here is pretty severe. It’s very windy here on Saturday and that would keep it dry.
But I’ve been thinking running the OS on Evapotranspiration is putting the cart before the horse. Currently we set a watering schedule, which might be once a week, and defeat that with ETo when it’s time to water. Ideally we would monitor the ETo and turn the sprinklers on as required, only putting on that much.
CanTurf recommends deep watering lawns:
“The most important ingredient in maintaining a healthy happy lawn is the development of a deep watering routine. Deep watering will encourage the roots of your lawn to grow deep into the soil enabling it to source increased water and nutrients-saving you time and money.
To develop a deep watering routine you should water infrequently and give your lawn a very good soak, ideally 12 mm (or half an inch) of water over the whole area every 10 to 14 days, or as required.”
So I have mine putting that much on every second Thursday in several bouts of 10 mins, 30 mins apart so it does soak in and allow the ETo watering defeat to modify that. I don’t want a bowling green, just enough so it won’t die, and I recently reduced the number of bouts to see if it was really needed.
I hope that helps and will report back when I update my OS controller’s firmware.