Most furrow irrigation systems operate at about 50 percent to 55 percent efficiency when you consider they put on too much water on one end of the field and not enough on the other. But there’s a way to get more water where it’s needed – and improve efficiency – as Jason Krutz explains in this video from the Delta Ag Expo.
Krutz, the leadoff speaker at a Irrigation, Voluntary Metering Program and Water Conservation Roundtable at the Expo in Cleveland, Miss., showed a computerized simulation of how irrigation water moves across a silt loam field when it's applied with a standard plastic pipe system. The simulation showed a line running across the field at the three-foot depth that represented the plant root zone.
"Anything that falls down below this (three-foot) line takes away from our efficiency; it falls below the root zone and the plant never sees it," he said. "Anything that runs off into the tail ditch, we lose and it takes away from our efficiency."
As the water moves across the field in a conventional system, it slows down because it is falling down below the root zone. To keep the water flowing to the end of the run, more has to be applied than the soil can take in and it runs off the end of the field.
"The numbers on this simulation tell us that furrow is about 50 percent to 55 percent efficient," said Krutz. "What that means is that if water at a two-inch deficit, you will have to flow four acre inches of water across this field to get the amount of water you need to recharge the rooting zone appropriately, and very few of you are doing that."
The surge valve avoids that problem by sending water in alternate directions, in pulses.
"Notice how quickly that second pulse skims across the zone that's already been wetted," he noted. "After it gets to the new wetting zone, it slows down, and it's just layering water in there. The last pulse takes water all the way to the end.
"I've been talking for a while now, and we still don't have any water that has left the rooting zone. You can dial this in to get a little more water to the end of the row. You may have some runoff into the tail ditch, but we're trying to make sure you get adequate moisture to the far end of the field."
For more on surge valves: Farmers making headway reducing irrigations and saving money.