Lots of trees. Not much water.

Discussion in 'Irrigation' started by sgbotsford, Oct 6, 2012.

  1. sgbotsford

    sgbotsford LawnSite Member
    Messages: 127

    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.
  2. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    .............. Pond

    ::wipes blood off face from bleeding eyes::
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,748

    Upsize the existing pump, rather than add a booster. You can always restrict the flow as you see fit to 'save the aquifer'
  4. sgbotsford

    sgbotsford LawnSite Member
    Messages: 127

    The issue with aquafer impaction is that you don't know until it's too late. No undo. Plus, restricting the flow means that I'm chucking energy away.

    The ideal situation when running a well, is that it doesn't shut off more than once a day. The start and stop and the fluctuating water levels in the bore are what wreck both pumps and wells.

    And it may be fine. I've got neighbors who pump 50 gpm. But we are in a complex area geologically. We've got various levels of tilted sandstones, limestone, dolomite, and coal. So it's a bit of a crap shoot.
  5. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,748

    If you need more water you have to pump more water. If 8gpm has been pumped in years past, it figures to work that way for the foreseeable future. The question becomes how do you get that 8 gpm to the furthest reaches of the property.
  6. bcg

    bcg LawnSite Bronze Member
    from Tx
    Messages: 1,865

    I don't know that this helps you much but the nurseries and tree farms in this area use overhead irrigation with impact sprinklers fed from a pond. They grade and setup drainage so that all the runoff goes back to the pond and do most of their watering off of that reclaimed water and what is added by rainfall (in most years) with very little supplemental water added to the pond from the well.

    I know this seems counter to doing everything on drip but since the majority of the water is reclaimed and the property is setup to funnel all rainfall runoff into the pond, it works out to be a very efficient setup.
  7. sgbotsford

    sgbotsford LawnSite Member
    Messages: 127

    Considered this. The soil here is very permiable. Typically I've got 2-5 inches of silt/sand/clay soil on top of fine sand. Run a garden hose on the ground for several hours, the stream vanishes in about 40 feet. This turns out to be an asset. I can do pot in pot just by boring a hole, and setting the socket pot in place. No need for complicated drainage.

    We have runoff in the spring when the snow melts. There's runoff because the ground is still cold enough that the start of the melt forms an ice barrier in the top of the soil. Once the snow becomes patchy, there is no more visible surface run off.

    To get enough water that my ephemeral stream starts up in the summer requires about 5 inches of rain within a week. Anything less than that vanishes into the pasture. We have had the ephemeral stream run during summer only twice in 12 years.

    In the long run, I guess I am recycling the water. It goes back into the aquafer and I get to pump it again. One reason that I'm very very careful about chemical use. I drink the well water. (The producing zone in the well is about 60 feet down.) I use almost no pesticides, and fertilizer is either top dressed granular, or applied at 100 ppm. Areas near pots are kept sodded so that excess fertilizer is picked up by the plants.

    The other downside of impact sprinklers is that the zones are too large. I've got a small operation. A cohort of trees (same species, same size, same pot) is typically about 300-600 trees. Each cohort needs to be consdiered separately.

    However, having enough flow would allow running a bunch of aquazooms instead of just one.
  8. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,748

    The money you might spend on a booster pump would be better utilized in a 3/4 HP replacement submersible pump.
  9. sgbotsford

    sgbotsford LawnSite Member
    Messages: 127

    I have a booster pump. It's actually a 1/2 horse shallow well jet pump. Got it free from a customer when I delivered a load of aspen, and we got talking.

    What I don't know: If I put a booster pump on it, will the dropped line pressure on the upstream side cause the well pump to cavitate.
  10. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,748

    just throttle the outlet of the booster

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