Variable-rate planting has become easier than ever—here’s what you need to know
Like many farmers, Matt Boucher has a field where the ground varies quite a bit. This particular field slopes west to east down to a creek and is pockmarked with areas that have high clay content.
“We could never get yields on those spots no matter what we did,” says Boucher, who operates a fourth generation family farm in northern Illinois.
So when variable-rate technology came along, it didn’t take much convincing for Boucher to put it to work in that field first.
“It just felt logical to us,” he says. “Why put more seed out than what the ground is capable of handling? The same goes for fertilizer. Throwing money at a bad spot might not be the best answer.”
For farmers who aren’t yet on board with variable-rate seeding, the technology has never been easier to use, according to Rudy Raatz, precision ag manager with Minnesota-based SEMA Equipment.
“Once you know the process, it’s surprisingly easy to set up,” he says.
A lot of third-party service providers can help, too—from Climate FieldView, WinField’s R7 tool, Farmers Edge, Farmobile and the list goes on. There are also dozens of trained precision experts at the local retail level ready to help. With the proper assistance, all the farmer really has to do is select the script on their display and everything else is pretty much automated, according to Raatz.
Laura Thompson, Extension educator and on-farm research coordinator with the University of Nebraska, says Boucher’s reason to get started with variable-rate planting was a solid one. That’s because VRT technology has bigger upside potential in fields that are highly variable. Some fields will be better candidates for the technology than others, she says.
The question Thompson fields the most from farmers is about how to set up management zones. Although a variety of information can be helpful (see info below), yield maps will provide the backbone of most successful variable-rate seed prescriptions—and the more, the better.
“Yield maps over time are an excellent starting place for developing management zones,” she says. “Soil series information is readily available, but should not be used alone to create management zones. And consider using remote sensing imagery or soil electrical conductivity to augment your yield information.”
Scott Speck, precision specialist with Nebraska-based CropMetrics, says before a farmer even looks at yield maps and field history, he or she should be asking a few simple questions first.
- “Ask why,” he says. “Right now, it is actually pretty simple to set up a variable-rate planting script. But you need to know why you’re doing what you’re doing. That will inform the entire process.”
- What is the end goal? Is it to finesse better yields? Is it to address areas of the field that you haven’t been able to advance? Is it to improve efficiencies and get the highest ROI?
“Our customers are asking about it for a lot of different reasons,” he says.
Asking these questions will also help farmers avoid turning to variable-rate planting to patch over other fixable problems in the field. For example, if there are underlying compaction, drainage or fertility issues, address those issues separately instead of trying to “solve” them with variable-rate seeding, Speck suggests.
- Does hybrid selection matter? Absolutely—it’s paramount to the process, according to Boucher, who sits down with his seed dealers each year to study hybrids, learning what populations are optimal in each of his management zones.
Speck says he approaches hybrid selection with similar scrutiny.
“I always ask—what are the limits in each zone?” he says.
“Sometimes you’ll get into a scenario where you think that VR failed, but you really just pushed a particular hybrid too far.”
Speck has another piece of important advice: “Analyze everything you do, and make sure you can always learn from what you did.”
That’s where check strips come in. Thompson advises putting in numerous check strips at standard rates. Replicate and randomize them. Variable-rate seeding is basically a science experiment, and all successful experiments require a hypothesis, the experimentation itself and a measurement of the results. Without the strips, useful measurements aren’t possible, she says.
“These strips can be evaluated overall for profitability of your decision,” Thompson says. “Yield in the check rate can also be compared to the variable seeding rates immediately adjacent to these checks.”
That information will help farmers tweak their variable-rate prescriptions for the following season, she adds.
There are stumbling blocks to variable-rate seeding, which are avoidable. For example, if the script doesn’t look exactly right when you roll into the field, tweak it.
“We had a customer who had switched to no-till the year before,” Speck says. “When he got to the field and saw those higher residue levels, he decided to swap to higher seeding rates to ensure good emergence.”
Most setups allow users to type changes directly into the monitor on the go, Speck adds.
Another common issue Raatz has seen is when users don’t set an out-of-bounds rate in the script. It’s not a problem in and of itself, unless so-called “GPS drift” happens during planting. That can happen when planting the outer rows and the GPS temporarily thinks the planter is outside the field boundary, even when it’s not.
To prevent planter row units from shutting off during this phenomenon, Raatz recommends setting the out-of-bounds rate as “average.” For example, if the field’s seeding rate varies from 32,000 to 36,000 plants per acre, set the out-of-bounds rate at 34,000.
After all the hard work of the season, don’t let postharvest evaluation get lost in the shuffle, Thompson says.
“It’s important to have a plan in place from the beginning that will allow you to verify that your changes were an improvement over your standard practice,” she says. “That sometimes gets overlooked.”
Time and patience are required from start to finish, Boucher adds. It’s like peeling the proverbial onion—every new layer exposed presents new insights to explore. Currently, Boucher is incorporating data gathered from soil testing into his prescription maps to further fine-tune them.
“We’re still learning,” he says.
7 Ingredients for Management Zones
If you think of variable-rate planting as a recipe, Pioneer agronomists say there are seven ingredients that can help a farmer “bake the cake.” Take the following into consideration:
1. Your own knowledge of yield history, crop rotations and general productivity of field areas.
2. Soil type, topography, landscape, slope and drainage.
3. Yield history spanning multiple years.
4. Crop productivity ratings based on soil type (if yield history is not available).
5. Irrigated and dryland areas of fields, where appropriate.
6. Soil electrical conductivity and/or soil color.
7. Remote imagery that identifies NDVI, bare soil and crop vigor.