irrigation Sunbelt Expo wet year

Shallow crop roots keep Expo irrigation systems on call

Irrigation systems at the Sunbelt Ag Expo continue to run, even in wet years. Every one of the research farm's 600 acres can be irrigated. The goal is to insure that research measures intended factors, and that results are not affected by spotty irrigation.    

Even in a wet year like southwest Georgia has seen in 2013, the irrigation systems at the Sunbelt Ag Expo research farm don’t remain completely idle.

Crops planted at the Darrell Williams Research Farm are managed at such a high level that some irrigation is required every year, says Michael Chafin, farm manager.

“This year hasn’t been so much about the large volume of irrigation required, but more about the timing of the irrigation applications,” says Chafin. From that standpoint, it has been a strange and challenging year for farming in south Georgia, he says.

“We’ve had periods of long, wet conditions followed by brief dry periods. As a result, our crops didn’t develop the root systems they would have in a drier year. The roots were very close to the top of the ground, so even one or two days without water caused plant stress,” he says.

Using soil moisture sensors, Chafin says he could see that while the soil was saturated at 8 inches, it was starting to become dry at the 2 to 4-inch depth.

“Even though we had plenty of water deeper down in the soil, it had started to leach and dry out closer to the surface where our roots were located. So even though it was a very wet year, our plants were starting to stress from dry conditions.”

Every acre of the Expo’s 600-acre research farm can be irrigated, says Chafin, and the one spot that isn’t irrigated with an overhead center pivot is watered by a sub-surface drip irrigation system that is being evaluated.

The idea, he says, it to help insure that research is measuring the intended factors, and that the results are not being impacted by spotty irrigation. The goal is to remove irrigation as a variable in research plots so that an improved cotton, soybean, corn or peanut variety will stand on its own merits and not be influenced by water intake or the lack thereof.


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 “We’ve currently got 11 pivots on the Expo research farm. Two of those are lateral-move systems. We’ve got five that are guided by GPS. Those five are computer-based telemetry systems with an Internet-based remote control package. Four of those are Reinke systems that can be controlled from the computer in my office or through a smart phone,” says Chafin.

Testing soil moisture sensors

The Expo also is working with different companies to test soil moisture sensors, he says.

“We tie those back into the pivots, using a service like WagNet, which allows you to remotely control and monitor third-party devices.  There’s a monitoring device on the pivot that can be monitored from my phone. It coordinates with the soil moisture sensors, and I can look at it all on the same app on my smart phone.  I can call up the water level in the soil, and if the moisture sensor indicates that the soil is dry, I can start the pivots and watch them from the same application on the phone.”

A recent upgrade to the Expo’s irrigation system is a propane-powered pumping unit that was donated by PERC — the Propane Education 7 Research Council.

“It replaced an outdated diesel engine that was uneconomical and inefficient,” says Chafin. “PERC is working to convert gasoline engines to propane. Their research has shown that propane pumps are cheaper to run than diesel and are competitive with electricity. We’ll be conducting some extensive testing starting next year.

“We were planning to do it this year, but conditions haven’t been ideal for irrigation testing. We’ll be running some head-to-head comparisons between the diesel, propane and electric systems through the same pivot on the same crop, and we’ll come up with some hard data on what it costs to run the same unit under the same conditions using different sources of power.”

Other improvements include new booster pumps donated by Cornell Pump Company.

“Cornell is donating booster pumps for all of our pivots to replace our existing booster pumps. We’ve had to replace pumps in the past few years that were worn out. These are the booster pumps on the end of the pivots that help to power the end guns.”

In southwest Georgia, where the Expo site is located, irrigation has expanded significantly, from about 25 percent of all cropland 20 years ago to anywhere from 55 to 60 percent today. So for the Expo to mirror what growers in the region are doing, irrigation is a must, and proper, updated irrigation is even better, says Chafin.

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