By Carroll Smith
Furrow irrigation, which has become more and more popular in the Mid-South, used to involve just rolling out pipe, punching some holes and turning on the well. Today, technology allows farmers to furrow irrigate more efficiently, reducing water, fuel and time.
Mississippi State University (MSU) Extension irrigation specialist Jason Krutz recommends three tools that fit well in furrow irrigation: computer-based programs (PHAUCET and Delta Plastics Pipe Planner), surge irrigation and irrigation scheduling.
“These computer-based programs make sure the furrows are going to water out at about the same time,” Krutz says. “We’ve shown that this increases irrigation application efficiency by 15 to 20 percent, which, on regularly shaped fields, saves $10 or more per acre.
“The Pipe Hole and Universal Crown Evaluation Tool, PHAUCET, takes into account key factors including pump capacity, pipe diameter, row lengths and differences in pad elevation to determine the optimum size holes to place in the polypipe so the furrows will water out more evenly.”
Another beneficial furrow irrigation technique involves surge irrigation, which is very effective on tight, silt loam soils with poor infiltration rates. Surge irrigation intermittently applies water to irrigation furrows, whereas water is continuously applied in conventional furrow irrigation sets.
Surge irrigation is usually completed in two phases, advance and soak. The advance phase pushes water across the field up to twice as fast as a conventional irrigation event. Surging normally requires four to six cycles per side to reach the tail ditch. Each pair of cycle times gets progressively longer. The soak phase begins automatically when advance is complete. Each soak phase flows from the top of the furrow to the bottom of the wetted field, which controls depth of infiltration and reduces or eliminates runoff.
“We have one producer in Mississippi who has up to 50 surge valves,” Krutz says. “Across the board he has seen a 30 percent savings in fuel, water and time. With this technique, a farmer can get the water across the field a lot faster and get more infiltration out of these surge valves than he does with a traditional irrigation set.”
An atmometer determines the evapotranspiration (ET) value, which accounts for the total daily water use in the soil profile attributed to both the plant and the atmospheric conditions.
“This is a really good irrigation scheduling tool,” Krutz says. “We also use the Arkansas Irrigation Schedu-ling Tool, which takes ET values into account as well.
“We use water mark sensors installed in the field at 6, 12, 24 and 36 inches,” he adds. “Depending on the soil type, a threshold triggers our irrigation events. We install four sensors that cost about $30 each. Then you plug a $50 handheld device into the sensors to read them. Telemetry packages also are available that will send the readings to you in real time.”
Stewards Of The Land
In a report from MSU, Mississippi Delta farmers also are using careful irrigation practices to conserve water in the alluvial aquifer. Jeremy Jack, an owner of the Silent Shade Planting Company in Belzoni, uses furrow irrigation on many of his crops on the family’s farm.
“We try to water 25 acres per 12 hours on each of our fields,” he says. “This allows us to get the water on and off so we don’t damage the crops by watering them.”
This system also slows erosion and prevents depletion of the aquifer.
Contact Carroll Smith at (901) 767-4020 or firstname.lastname@example.org.