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Serving: NE
irrigation equipment in corn field
QUICK RETURNS: UNL's TAPS farm management competition shows a quick return on investment by scheduling irrigation based on soil moisture information.

Competition highlights returns from monitoring soil moisture

It's easier to schedule irrigation in a dry year, but how much water could be saved during a wet year?

This marks the third year of the University of Nebraska-Lincoln's Testing Ag Performance Solutions farm management competition. This year, there are three competitions — including pivot-irrigated corn and grain sorghum competitions, and a subsurface drip-irrigated corn competition.

Two of the key drivers of the competition are profitability and input use efficiency, and it offers participants a chance to try new methods and technology that can help growers be more profitable and use nitrogen and water more efficiently.

"It is kind of a learning process — if you put on less water. If you aren't monitoring soil water to know how low you can go, you can't really guess," says Chuck Burr, Nebraska Extension educator and one of the organizers of the TAPS program. "It's pretty easy to irrigate when it doesn't rain. With the frequent rain we've received, you can really use soil water technology to maybe hold off until later in the year and potentially save a lot on pumping costs."

How much can be saved? In last year's TAPS competition, the lowest amount of water applied in the corn competition was 4.5 inches, while the highest was 11.5 inches — a 7-inch range in the total amount of water applied. In previous years, the average pumping cost for the TAPS competition has been about $7.80 per acre-inch of water.

"That's over $50 per acre,” Burr says. “That can be a significant portion of your operating costs just by reducing your irrigation applications. It would be pretty easy to pay for a new soil moisture probe like that. When you multiply your pumping costs by 2 or 3 inches, that adds up pretty fast."

This way, he adds, growers can use soil moisture earlier in the growing season, allowing the profile more room to store additional rainfall — which there has been no shortage of this year. And, as the growing season progresses, it's important to have enough water to finish corn.

Burr notes that once corn reaches the early dent stage, it needs about 5 additional inches of water to reach black layer regardless of weather conditions. Soybeans also use more water per day once it gets hot and dry, but they finish based on day length rather than growing degree days, and likely will use more water than corn to reach maturity.

"The other critical time to watch soil water is at the end of the season,” Burr adds. “If you can dry that profile down as we get into late August and early September, and deplete the excess moisture that's there, we've far and exceeded refilling that profile the last couple years, easily. Just because we've had so much offseason moisture to replenish that 4 or 5 inches, it's been pretty easy to do. So, you save several inches at the end of the season, and you'll pay for those probes in a hurry."

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