I have an automatic drip/soaker irrigation system for my vegetable garden, and I am starting to see a problem that I think I can solve with Arduino. I am a tinkerer and can follow directions, but I am NOT a programmer. The issue is I have a Toro ECT XTRA controller with 10 zones. It has the external wireless weather/rain sensor (which automatically increases/decreases watering time based on temperature and sun exposure), but I have vegetable beds and containers in various places that get varying amounts of sun.
I am finding that the beds that are shaded for part of the day are getting way overwatered, even after cutting down their watering times - and our weather has been kind of wonky, 96 degrees yesterday, 73 today with some rain, 75 tomorrow, 101 Tuesday.. The automatic compensator averages over a week, so right now it's watering at 120% - even though it's not as hot as it's been.. So I can't just set them on a different program with alternating days, because if it gets really hot they will dry out. The rain sensor is set to trip at 1/4", but I find that it dries out too fast and resumes the schedule while the ground is still wet. I also can't really set a manual 24 hour rain delay, because that overrides all zones and the containers will start to dry out.
So here's what I'd like to do. I don't want to build an entire new controller or use OpenSprinkler just yet. And all the Arduino projects I've seen using moisture sensors are made to activate pumps and such. What I want to do is use a moisture sensor (or two averaged) per bed to simply activate a relay to bypass that zone while it is too wet. The timer will still run its schedule but any zone with a sensor above threshold will not open its valve.
Ideally each sensor would be wireless (I could do battery or solar), with a single receiver on the Arduino that would be placed near the timer/relay board. It would not be a huge issue to wire everything though, I have outdoor Cat5, and the longest run would be about 100ft. A pair of Arduinos (one outside that connects to all the sensors, and one inside that connects to the relay board) connected by a single cable would be great too if that's possible.
Is this a realistic project? The hardware part is absolutely no problem for me but I would need some hand holding to write the program..
Thanks in advance!