Shannon Krueger 1

February 1, 2012

9 Min Read


Driving with a broken fuel gauge isn’t just inconvenient, it’s risky. So most logical drivers would keep the tank full for fear of running out of fuel at the most inopportune times – or better yet, fix the fuel gauge. The blind hope required to drive with a malfunctioning gauge is exactly how Nick Lammers describes most folks’ approach to moisture management.

 “Since most growers don’t have a gauge to determine how much water is in their field’s soil profile, they often follow the same strategy,” says the AquaView team lead for Fontanelle Hybrids of Fremont, NE. “They can’t afford to run out, so they just keep the profile full.”

That’s changing with the increasing affordability and ease of use of moisture-monitoring technology.

 “Growers know that the chief limiting factor to economic yields year in and year out is water, especially as you move west in the Corn Belt,” Lammers says. “Soil-moisture probes give you the gauge so you can make better decisions on when to fill up.”

Moisture monitoring offers significant benefits in decreased fuel costs and better environmental stewardship, says Gary Zoubek, University of Nebraska Extension educator in York, NE. In 2005, the university began working with 15 growers using the technology. Today, the study has exploded to more than 500 growers as word spreads regarding the value of the technology.

As restrictions increasingly affect how much and when that water can be applied, it is critical to know the moisture available in the soil profile, Lammers says. A wrong decision on timing or application amount can waste water that will be critical during reproduction. 

“We can’t afford to guess in those situations,” he says.

Moisture is hard to come by in the dry, windy climate of southwest Kansas, where Steve Arnold farms with his wife Kathleen. Until three years ago, about one-third of their farm was irrigated. Then their precious supply of groundwater from the Ogallala Aquifer began to run out.

Despite more widespread use on irrigated land, dryland use of moisture-monitoring technologies has been increasing, especially in situations like Arnold’s.

“People wonder, ‘Why care about it if you can’t control it?’” Arnold says. “It makes it that much more important. If you can’t get water when you need it, you need to know how much you’ve got. Our thought process was that we didn’t want to get behind because we couldn’t catch up.”

Knowing how much moisture is in the soil profile may prompt growers to change their management practices, says Bruce Moeller, CEO of AquaSpy. They base hybrid/variety selection or plant populations on the soil’s moisture and nutrient characteristics.

Even though little can be done to correct moisture deficits in dryland operations, moisture probes can help provide data to diagnose problems.

“The moisture probes can tell you the amount of stress that was present in the field due to water or lack thereof,” Lammers says. “With that information in hand, you can get a better idea of the effectiveness of your other inputs.”

In just the first few years, Arnold has noticed a difference. “During our irrigation days, we used to waste more water than we use now to grow a crop,” he says.

Arnold bought his first probe about three years ago and installed it in one of his last irrigated fields. He watched the root activity change from day to night, fascinated by the ability to see when the plant was actively growing. When a moisture event occurred, he could watch the soil profile recharge and monitor plants’ water uptake. He could even observe how hot or cloudy days affected the soil profile.

 “We’re used to managing what we can see on top, and now we have the tools to see what’s happening below ground,” he says.

Arnold also added a PureSense weather station, which reports every 15 minutes to his mobile phone a multitude of data including wind speed and direction, relative humidity in the air and crop canopy; and temperature of the soil, air and crop canopy. It also includes a rain-gauge bucket. A solar panel keeps the battery charged to uplink to via radio signal or satellite.

Zoubek says that many participants in the Nebraska Ag Water Management networks use atmometers or evapotranspiration (ET) gauges along with crop-growth stages. This simple tool takes into account all the information that a weather station provides to estimate the crops’ ET rate, Zoubek says.

Using probes from AquaSpy and Sentek, Arnold is able to measure moisture in the root zone with 3- and 5-ft. probes that sense every 4 in. down the probe. Sensors monitor net changes in soil moisture, as well as drainage, rooting depth, compaction, soil temperature changes, depth of water infiltration and much more.

Moeller compares moisture probes to a cellphone for plants. “As humans, if we get hungry or thirsty, we just go get what we need. The plant’s root system is communicating with the soil that it needs more or it needs less,” he notes. “We’re really the crop whisperers because we can hear what the crop needs.”

Those messages get even clearer as technology and services improve. In addition, a variety of systems, such as the one from John Deere Water, offer data on the go.

“The John Deere Water system is all Web-driven so the growers can get up each morning, fire up their laptops or smartphones, check the weather, markets and field irrigation needs in just a matter of minutes,” Lammers says.

Enhanced software enables producers use to improve their decisions, Zoubek says.

This real-time data lets farmers determine timing of chemical applications, Moeller adds. During high-growth stages, growers can apply the right nutrient in the right amount at the right time to get the maximum yield out of the crop.

In addition, Fontanelle’s AquaView offers certified water consultants to help interpret data. With extensive training in correlating data to soil characteristics and crop physiology, these professionals watch for trends where growers may be applying too much or too little water based on the active root profile and make recommendations to correct those situations, Lammers says.

“It’s not something you have to do alone anymore,” Arnold notes.

Regardless of probe type, what matters most is proper installation in soil textures that represent the management zones in the field.

Arnold recommends putting one probe in the best soil type and another in the worst. He uses a Veris soil cart to map soil textures, which correlate to moisture-holding and -release capabilities. He reports almost a two-fold difference between sandy soils, which typically provide his best yields, and heavy clay soils, which retain the moisture but don’t release it to the crop.

Lammers agrees. “We want to put the probe in the most representative part of the field as we are going to make decisions for the whole field based on what we are seeing at that location.”

Zoubek and Moeller both recommend at least one probe or set of sensors per center pivot covering up to 135 acres, as long as it’s placed in a representative management unit.

Moeller likens each probe to a member of the House of Representatives, reporting back on the needs of its constituency.

Arnold does exactly that with four strategically chosen dryland fields representing differing areas of production. It helps him decide where to go with equipment, make management decisions and select crop varieties.

Probe placement can differ for pivot irrigation systems, which apply a uniform rate across the field, versus variable rate irrigation systems, which offer different management zones. For pivot systems, Lammers recommends placing the probe in the majority soil type to set an irrigation strategy to reflect the moisture conditions with that part of the field.

“That means we may overwater or underwater parts of the field, but economically it is still our best solution,” Lammers says.

In variable-rate systems, probes can be placed in several soil types, and water rates can be adjusted for optimal application by zone.

Moeller also cautions growers to place probes where the communications tower portion won’t be knocked down by center pivots. In addition, he recommends installing probes about three-quarters of the way from the middle of the circle to obtain the most accurate data.

Overall, it’s important to ask questions and understand what the readings mean for each soil type, Zoubek adds.

When it comes to numbers, the return on investment can really add up.

Fontanelle AquaView study results showed $11.35/acre in fuel savings and $25.55/acre increase in yield using corn at $4.50/bu.

“If you equate that to a 130-acre pivot it would mean the grower has an additional income of nearly $4,800 on that field,” Lammers says. That doesn’t account for reduced costs in repairs and labor.

The return on investment can easily be more than 200%, Moeller says of AquaSpy.

“Typically we see our customers saving 3 acre-in. of water per season, some quite a bit more or less, plus the cost to pump that,” Moeller says.

Similarly, growers in Nebraska show a savings of 2 in./acre, Zoubek says.

“This is a tool that allows you to put the right thing on at the right time in the right amount,” Moeller says. “If you do that, you’ll get a better yield, but the impact is exponentially greater than even saving on input costs.”

Some AquaSpy customers report increased yields of 20-30%, Moeller says, but they’re pleased to see even 1% better.

In addition, the technology helps prevent unnecessary chemical applications.

“If the soil is already full, then anything you’re going to put on is waste,” Moeller says. “By adhering to our system’s alerts you’re saving yourself time and money.”


Moisture-monitoring technology has changed the way Arnold farms because of its ability to measure the effect of management.

“I used to feel like I had a pretty good gut feeling for things like that, but I like to see numbers and soil moisture monitoring gives me those numbers,” he says.

Arnold hopes to eventually create a soil moisture balance sheet – like a cash flow balance sheet – to measure the monetary value of different soil textures and tie dollars to his data.

“I think it will make us much better stewards of the soil,” he says. “We’ve been guilty of taking advantage of the resources we’ve had in the past and we need to do a better job of taking care of what we’ve got. This tool helps us do that.”

Lammers agrees.

“Long term it’s about sustainability. We have to make sure we are efficient as possible with all the resources we use for production agriculture, but water may be the most critical,” he says. “The Ogallala Aquifer is shrinking each year, and if we want to ensure profitable production in those areas so our children can continue to farm, we have to start using technology like this today.”

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