Let's say the RoboWater(tm) rolls down a row of trees in the orchard, water hose unreeling behind it. At each tree, it dumps the calculated dose of water into a clay pot that is sunken into the ground near the trunk (from which the water slowly soaks into the soil). When the row is done - it reverses direction, reeling the hose back up in the process. Then some side-shuffling, and it's soon rolling down the next row of trees in the orchard, again dumping the calculated dose of water...

Oh, I wasn't thinking orchards. I thought OP was talking about row crops which can't feasibly be irrigated with hoses.

> I thought OP was talking about row crops which can't feasibly be irrigated with hoses.

Are we talking about irrigation pivots[1] here? Because those are a known technology.

If we are thinking about robots driving up and down the rows and watering plants from a tank, and then returning to some central location to re-fill their tank that feels like a "carrying water for elephants" situation. I suspect the logistics won't work out. Could try to run some numbers on it of course. Is that how you are thinking about it?

1: https://www.youtube.com/watch?v=7j1lMs7fcIQ

Yeah, and I think you're right. I hadn't even given any thought to the massive weight of the water tank you'd need to do this. I was thinking of it more like a sprayer, which requires a much smaller volume to be useful.

The other issue is the ability to respond to extreme heat quickly enough.

We work with fruit growers in South Eastern Australia where temperatures routinely hit high 30s and even low-mid 40s (°C) a few days each year.

Those growers want to see our soil moisture data readings updated every 15 minutes so they can turn the drippers on very quickly as soon as the soil starts drying out rapidly.

It would just be too slow to rely on robots driving up and down the rows in those conditions.

Row crops can be (and already are) irrigated with hoses. In dry areas of the world, drip tape is buried throughout the entire field because it allows farmers to make more efficient use of the water available to them. It does require the machinery has auto-steer (which is standard practice now anyway), because tearing up the drip tape with a planter is an expensive mistake.

https://whyfarmit.com/drip-tape-irrigation/

Really? I didn't know that. Just didn't seem feasible to have irrigation lines running for that distance.