As we developed plans for several of our research orchards in CT, one of the missing links in our infrastructure were flexible systems for irrigation and delivery of fertilizer. E-mails to the various nut grower forums and Chapter mailng lists returned a wealth of information. Not surprising, much of it with strong opinions and even contradictory. After evaluating all the solutions suggested, we've come up with a reasonable solution that meets our specific needs. Clearly, had our needs been different, we might have arrived at a different solution.
Thanks especially to Dr. Fred Hebard of the TACF Meadowview Farms, and Tim Phelps of Penn State (and PA-TACF) whose response to my questions, I print almost verbatim below. Their solutions were remarkably similar and both based as much on applied practical usage as theory. If you have any ideas to add, please use the comments function to add your thoughts to the article.
Here was how I originally posed the questionproblem.
What we're interested in is a low-cost, light-weight system serving as a combination irrigationfertilization system for a small (500 tree) Chestnut orchard.
This system should be able to be mounted on a trailer or the back of a pickup. The self-priming (preferred) pump should be powered by a gas (preferred) or 12vdc motor (possibly).
The system should be able to dispense at the rate of 10 gpm to two wands (20 gpm total) thus optimally watering about 40 seedlings per minute. This would allow watering an orchard in about 15 minutes with two to three volunteers. The setup would include two 55 gallon plastic drums into which the fertilizer is mixed with water. The pumps would draw directly from these refillable tanks.
Here was the response from Tim Phelps.
Bill,
Sounds like you are in the same predicament I found myself in a few years ago with the installation of our large Graves orchard. There was very little information available for a small, mobile irrigation system, so I basically pieced one together. My needs were to water/fertigate 1,800 trees. I had a compact tractor and limited access to 3/4 ton truck. The truck could be used for watering, but not with injected fertilizer, since the salts from fertilizer could damage the paint of the truck. So, I found a small 2-ton utility wagon from NorthernTool (didn't/still don't care about paint on the wagon – adds character), which could be pulled behind the tractor, although extremely cautiously on slopes. It's weight capacity allowed for a larger water tank, thus reducing number of fill-up trips, so I went with a 325 gallon tank. Filling is time consuming, as long as 20-30 minutes from regular water hose. Fortunately, near the Graves orchard, there was access to a water trough, which could fill it up in 5 minutes. The wagon has since been used for many other valuable, time-saving operations like mulching and brush removal.
The (Honda) WMP20 water pump was chosen based on its ability to transfer chemicals, in my case liquid fertilizer, which, initially, I added Miracid to the water tank at 300ppm. That required hauling multiple bags of fertilizer to the field, weighing the appropriate amount in a 5-gallon bucket, and dumping it in the small hole of the tank. Later on, I got a portable fertilizer injector enabling me to make a concentrated mix prior to going to the field, thus eliminating weighing and mixing in the field. The pump has 2-inch diameter ports (suction/discharge). A 2-inch diameter hose pumps the water out of the tank. I made a reducer for the discharge to enable a 3/4″ hose (50 foot long) attachment. I checked with Honda prior to ordering the pump to make sure the engine could handle the pressure this would create, and they said it could. When fertilizing, the portable injector is connected to the discharge with a short 3/4″ hose, then use the 50' hose post-injector. When the injector is not needed, quick-connectors make it easy to switch hose connections. This pump does have high-capacity discharge at full throttle, but puts out ideal plant watering pressure when running the throttle near idle. A 5 count at this engine speed equals one gallon (~12 gpm). It's quite easy to steer (tractor or truck) with one hand and hold wand with the other for a do-it-yourself operation, but you should be able to split the discharge into multiple hoses if needed. However, the manufacturer did suggest the discharge NOT be interrupted (i.e. no shut-off valve) due to stress on the pump. Leaving it running from tree-to-tree causes some waste, but it's never been too much of an issue. The pump chamber requires initial fill-up, but is then self-priming once it gets going.
- Total cost: ~$2,360
- wagon = $1,000
- 325 gal. tank = $260
- water pump = $550
- portable fertilizer injector = $550
- …abundant, well-timed rainfall = $priceless
All of this equipment is used individually for other projects as well. If you're planning to use a truck and only water (no fertilizer) you could get a less versatile pump, thus reducing the cost.
I'd be interested in learning of other's experience with this also. Tim Phelps
