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‘SoyWater’ software assists irrigators

It takes around 20 inches of moisture for soybeans to yield 75 bushels per acre. That’s a half-million gallons of water. Moisture comes from the soil and Mother Nature, and can be added with irrigation.

But quantity of water probably isn’t the most important factor. Timing of watering is key for profitable soybean production, says Jim Specht, University of Nebraska professor of agronomy and horticulture. “Advance knowledge is money in your pocket,” he says.

Specht and a team of researchers at UNL have developed a Web-based production tool, known as “SoyWater,” to predict the stage of growth and water use for individual fields throughout the growing season. This new tool was rolled out in 2010. This summer it has taken on the road through nine farm visits by the BIT Mobile, a traveling technology classroom. Farmers can enter their soybean information on site, with help from researchers who designed the program. Stops were made at the farms of each district director with the Nebraska Soybean Board, which has supported the development of the system.

At the Lisa and Jim Lunz farm north of Wakefield, Specht told a group of farmers that SoyWater is particularly useful for irrigators. About 45% of all soybean acres in Nebraska are irrigated. SoyWater was developed to account for evapo-transpiration and water use at specific crop stages. Farmers often make the mistake of irrigating soybeans too soon. Irrigating before the R3 stage of growth only produces vegetation, not additional yield, Specht says. By logging onto the SoyWater website, farmers enter their field location, planting or emergence dates, soil type for their fields and maturity group of the seed.

The software utilizes local weather reporting stations to produce a table that tells farmers exactly when their soybeans will reach the crucial R3 stage, according to Specht. Because of the variations between weather stations, farmers can override the local weather report and put in precipitation numbers from their own rain gauge. SoyWater also takes into account when heavy rain events occur and much of the precipitation runs off.

“My theory is that we want to use every bit of water from the field that is annually rechargeable,” Specht says. Overwatering is a waste of water and money. “If I water my soybeans with an inch, I want an additional 3.5 bushels per acre,” he says. SoyWater helps improve water use efficiency for irrigators, but it also accurately predicts crop stage and water use at specific growth periods. “It can predict the calendar date when the soybeans will bloom.”

The tool is useful for dryland farmers, too. Lisa Lunz, who farms with her husband, Jim, and serves as chairwoman of the Nebraska Soybean Board, says, “I see it as a great tool for irrigation scheduling, because all you need to put in are planting or emergence dates, field location and maturity. But as dryland producers, we enjoy watching the water use.”

If farmers know when their soybeans will reach certain growth stages, they can better manage treatments of fertilizer, herbicides, fungicides and pesticides.

Farmers tend to irrigate soybeans like corn, which is a mistake, Lunz says. “Water use will continue to be an issue, and it is going to be more critical in the future,” she says. SoyWater helps irrigators water at the proper growth stages, but they don’t need to input a lot of information.

For more information, go to, or call 402-472-1536.


LEARNING BY DOING: UNL researcher Dr. Jessica Torrion helps Ray Kneifl of Dixon work through the SoyWater program.

This article published in the August, 2011 edition of NEBRASKA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.