July 23, 2012

H2 Oh?

Evapotranspiration (ET) gauges, like the one shown 
here, let farmers know how much water corn plants 
have taken up from the soil and evaporated
into the air. Watermark sensors keep track of how
much water is available in the soil. Combined, these 
two technologies give an accurate picture of water
 use and reduces irrigation amounts, saving both water 
and the energy dollars to pump it.
A network of sensors lets farmer Mark Jagels of Davenport know when he should water his corn crop and when it makes sense to wait a few days.

This is key information because Jagels wants to use the least amount of water possible but still produce a good crop. When needed, supplemental water in most cases is delivered through a pivot – a large sprinkler. It’s pretty common in Nebraska to see pivots providing water to corn during the summer. Nationally, though, only 11 percent of the corn crop receives supplemental water from irrigation. The rest relies only on rain - which is a much needed commodity right now during this widespread drought.

Because Nebraska is unique in terms of irrigating corn, researchers have done a lot of work to help farmers best manage this natural resource. That includes the network of sensors managed by the University of Nebraska that Jagels and other farmers follow online.

Some farmers, including Jagels, also install their own sensors so they can manage water use more specifically for their location. “The investment is worth it,” he said, “because the cost of buying sensors is easily offset by leaving pivots shut down for longer periods of time.”

The sensors used by Jagels and in the university network are watermark sensors and evapotranspiration, or ET, gauges. The university has some great websites and information that assist in this easy to use technology. Look herehere or here for various articles on ET gauges and crop water use.

Watermark sensors are buried in the soil at different depths and tell farmers how much moisture is available to their crop. ET gauges tell farmers how much water their corn crop is transpiring. Combined, these tools tell farmers how much water the plants are using and when they may need to irrigate.

Research using these tools has shown farmers how to reduce their water use up to 25 percent while still achieving good yields. “When it’s hot and sunny you want to believe it is drier than it is, that the crop is using more water,” Jagels said. “We’ve learned that isn’t always the case. The technology available today lets us know it’s okay to wait a few more days before irrigating, and that saves money, energy and water.

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