For commodity crops like corn and soy beans, lower prices and high supply can squeeze the bottom line, forcing growers to wring everything they can out of their crop while working with limited resources such as water or capital.
Minimizing production costs is a year-long effort for growers, especially in regions like the High Plains and Midwest, where the season is shorter and factors like weather and water access are becoming more prevalent due to falling aquifer levels and drought.
Hortau High Plains Regional Manager, Doug Larson, has been working with growers in those regions the past several years to help them overcome challenges related to water and energy use by using Hortau’s precision irrigation management system to monitor soil tension. A large majority of Larson’s clients use pivots to irrigate, which can be extremely expensive to operate, especially for those growers using electricity to power their equipment.
“If we can save them inches of water, we’re saving them power as well,” Larson says. “A commonly used number in our region of the country based on electric rates for pivots (circle), is 1 inch of water translates into about $750 to $1000 in pumping costs.
“Of course it all depends on what type of power they have, what volume they pump and how deep the well is. So, that number changes here and there. Those people that are using natural gas pump much cheaper, but for the majority of our clients using electricity as their power source, it translates well into that. If we can save someone 2 inches of water, which we can certainly do in most cases, we could actually pay for the Hortau system just with the energy savings.”
That said, there is not one single action at a single time that a grower can make during the season that will reduce irrigation totals by inches come harvest time. Rather, it is the culmination of small adjustments like reducing irrigation times here and holding off on irrigating there, all while making sure to be mindful of applying water based on the crop’s actual need.
We recently had a chance to sit down with Larson to discuss some of the irrigation and energy challenges growers in his region face. He touched on what a typical season would look like for a High Plains corn grower using Hortau to monitor soil tension data and how using that data to make informed decisions on irrigation amounts and timing is helping them recover production costs over the course of the season.
EARLY TO MIDSEASON
One of the biggest questions growers face when planning out an irrigation management strategy prior to the start of the season is how much water will be available to them.
Colorado corn growers may be entitled to more groundwater than a grower five miles away, but coincidentally on the other side of state line in Nebraska. Knowing the allotment and knowing how much water is in the soil are the key factors in laying out an irrigation plan.
“Some Western Nebraska Counties are restricted to 13 inches in a particular year, and they can bank that water,” Larson says. “Right across the border, on the same county road, we could have clients on the other side that are in Colorado that can be putting on 19 or 20 or 22 inches. They’ve got to utilize that water as best as they can. They can’t put on any extra, they need to put it on only when it’s needed and in those cases, we can really help.”
Getting equipment in the soil once snow has melted and the threat of more snow or frost is gone is a good starting point for most crops. For corn, once the stand is established, it’s important to get the equipment in right away to get an early look at how full the soil profile is.
“Once the crop is up, we make sure that the stand is what we wish it to be so that when we’re installing the equipment it’s in an area representative of what we want to see in the field,” Larson says.
Installation for corn typically involves sinking tensiometers to 8-, 18- and 30-inch depths after germination. Once installed, the system immediately begins sending soil tension data points, in real time, allowing the grower to see where and how much available water is in the soil profile, which, in turn, helps growers anticipate how much and when they’ll need to irrigate once planting has occurred and the stand begins to reach for water to uptake at the 8-inch depth.
“Many farmers would typically be putting on ¾- to 1- inch in a full pivot pass (in corn) in the early part of the season,” Larson says. “If the lower part of the profile is full, there would be no reason to put on an inch. We could get by with half an inch, and so each of these stages is a quicker pass, with less water, which saves us energy (and) water.”
Not only that, but early season is when nutrients are moving down away from the profile. If the soil is already at capacity, over-irrigating could push those nutrients below the active root zone and potentially open the door for leaching.
By July, corn begins to shift most of its uptake from the 8-inch mark to the 18-inch mark. From this point on, most of the uptake occurring for the rest of the season takes place in this zone, with the exception of late in the season, but even when plants begin to uptake at 30 inches, the majority of its uptake is still happening at the 18-inch zone.
During the midseason months, growers may see tension rise slightly higher and more frequently at the 8-inch depth due evaporation at the surface and movement of water deeper into the soil profile. Maintaining the proper soil tension in the effective root zone and seeing how quickly that works its way to the 30-inch sensor helps growers have a better understanding of the rate of infiltration so they can anticipate precisely when to fire up the pivots and know how much water to apply to keep the crop healthy.
LATE SEASON AND BEYOND
By early August, moisture uptake begins to occur at the 30-inch depth, with a majority of it still happening in the 18-inch range. This is the time of year the crop is in full production mode as tassels emerge for pollination and eventually on into crop maturity and harvest. A lot of water is being used and it’s important for growers to be diligent about keeping an eye on soil tension to make sure that the crop isn’t stressed from too much or too little water in the active root zones. In the case of heavy water application, soil tension can give the grower a good perspective on whether water is being pushed lower than it should be.
“If we start getting too much below that 30-inch depth, we’re missing the critical zones,” Larson says. “We want that water to be available in that range of profile so that the plant doesn’t have to exert extra energy to meet its uptake needs.”
In mid-September, most corn growers on the High Plains have stopped irrigating, but if the crop is not quite ready for harvest growers are still faced with the question of whether or not to run one more irrigation.
“We know when the plant stops its uptake, we can see when that occurs through our technology,” Larson says. “It’s very apparent to us that the plant is done at a certain stage and a common question is whether or not they should run another pass. The truth is, even late in the season, if the plant is still pulling water and needs water, we should be supplying that water. We can help them determine whether a last pass is needed.”
After harvest has wrapped up, it’s still important to continue to keep an eye on soil moisture heading into the late fall and winter months.
If the grower has been able to reduce water use over the course of the season, but notices that the soils are drying out, it may be beneficial to add some additional water to the soil. The reason for this is because when soils dry out, it can become hydrophobic which creates a barrier of sorts. As winter comes with its rains and snows, if the soil is too dry, the melt ends up running off instead of moving into the soil where it can be stored for the following season.
“The hope would be, generally, that we don’t want to deplete every bit of moisture in the profile as the season ends,” Larson says. “We want to be able to go into the winter and into the following season with some storage of water.”
If you would like more information about using soil tension to streamline your irrigation management program, contact a local Hortau representative at 805-545-5994.