Lots of trees. Not much water.
I have a container based tree nursery.
The farm is in Central Alberta, an hour from Edmonton. Bud break is 2nd week in May. First frost generally mid September. Temperatures over 25 C (77 F) are considered hot. We may get a week of above 30 degree weather a year. (86 F)
I've got 2 niches. One niche is 1 liter to 1 gallon trees and shrubs for reclamation. The other is "trees big enough to miss with the mower, small enough to plant by hand" mostly to acreage owners. (Ok, three niches. Lot of swedish aspen to people who want something taller than a 6' fence for back yard privacy.)
My pot yard starts 800 feet from the house, and extends back another 800 feet. The trees are watered from the well at the house. I've got a 1.5" main line from the house water system, This makes for a flow speed of a few inches per second. Water hammer is not a serious issue for me.
The well can supply 8 gpm at the house, but it's 30 feet up hill to the pot yard. 75 psi at the house works out to 45 at the top end of the pot yard. I typically can get 4-5 gpm at the pot yard.
Here's the setup at the yard:
From the mainline, I've got 8 hose bibs. Some of them have the ten buck Canadian tire mechanical 2 hour timers, some have the DIG digital timer. Each bib has a hundred foot hose with a quick coupler.
1. I've got 10 blocks of of 300-400 pots per block set up with 1 gph flag emmitters. I try to schedule it so that every block gets watered every 4 days. Time the water is running is adjusted for the weather. These currently are run off manual timers. I move the end of a garden hose to the zone connector. Everything is on quick connects. I went with flag emitters because they are cheap, and cleanable. Most of my blocks are set up on slight down grades so the slope compensates for the pressure drop along the line.
2. I've got one block that is 40 x 200 feet that I water with a Gardena Aquazoom oscillating sprinkler. This block is mostly 1 liter styroblocks up to #2 pots. Rows run across the strip, pots packed 4-6 feet wide. The Aquazoom can do the full 40 foot width, and do 3 rows at a time if I don't have any other water running. It takes a day and a half to do the entire block at 1 to 2 hours.
3. I've got one block 40 x 200 that is done with antelco inverted sprinklers on overhead lines, about 10 feet up. Each line has 20 sprinklers at 5 foot spacing. I'm not completely satisfied with the evenness of this. At present it's dvidied into 4 zones. It';s on a DIG timer, which runs for 6-10 hours each night. (So each zone is done once every 4 days.) I may run another pipe and make it every 6 days, so that I get better uniformity.
I'm looking at moving more pots to drip irrigation, as it's more efficient, and also gives the trees more room to spread. But part of that is setting up a system where the pot is secured and can't be knocked over by the dogs and coyotes. (Both do mousing for me. Cats are useless. The coyotes, owls, and hawks eat them too fast.)
Another option is to oversize the pot. This would mean that natural rainfall would do the bulk of watering. But this also means that in a dry spell, I may not have sufficient water to keep up. And I have to set them up for irrigation anyway.
At this point I'm pretty much at the limit of what I can water.
Ways to increase the water supply:
1. Put a booster pump on the pot yard line. This would allow me to use the full potential of the present well pump.
2. Replace the well pump with a 3/4 hp or 1 hp pump. (It is presently 1/2) I've heard lots of stories about wells that would pump for years at 5 gpm. Run them at 15 gpm and silt in the aquafer starts to migrate, packs the drawdown zone, and turns it into a 1 gpm pump. This could be truly 'bet the farm' decision.
3. Make a reservoir that can handle a minimum of 2 weeks continuous watering. This is kept full by the well pumping during the cool weather, and drawn down during hot weather. (We don't get a lot of hot weather.) To keep it from having the same issue as the pond, I would need to do something like a large black plastic bag in a dugout to keep the water clean and algae free.
4. Attach a pump to my pond. This is not trivial, as the pond, while clean as ponds go, has all sorts of crud that needs to be filtered out to run micro-irrigation, as well as all sorts of nutrients to foster algae/bacteria growth in the plumbing. It would require at minimum a trash screen, sand filter, 100 mesh screen filter, and 200 mesh disk filter, and a chlorinator that would kill the algae/bacteria, but not kill the plants.
5. Dig a second well. There goes 20 grand.
Comments & Suggestions welcome.