We need to hit the “easy button” on variable rate fertilizer and move away from the default blanket application. But for that to happen, the variable rate (VR) system must become as seamless and easy as the blanket application. And more profitable.
One can envision an on-the-go system like optical weed spraying, except in this case it would work for fertilizer. Sensors at the front of the tool would identify the soil nutrient situation and a rapid computer would process the information and adjust fertilizer metering on the fly.
The computer would already have baseline field maps and productivity zones built from historic yield and field topography. Ahead of the season, the farmer would set a yield goal for each zone based on the crop and the soil moisture situation. Soil moisture assessment could come from provincial maps, manual soil probes or permanent in-field moisture sensors to give a time-of-application assessment of soil moisture.
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Beyond that, all rate adjustments are done in-field, on-the-fly, automatically.
The author shared this idea with three industry experts. Here are their responses.
Tyler Lund
Veris Technologies
“We’re all looking for that holy grail,” says Tyler Lund, Kansas farmer and vice-president at Veris Technologies, a company that makes soil scanning equipment. “Obviously there has to be some way to get there eventually, but we’ve been banging our head against the wall since 1996.”
The problem, Lund says, is that we’re asking sensors to instantly identify tiny amounts of nutrient in real time. So why don’t we try instead to estimate soil nutrient content without actually measuring it.
Physical and biological soil properties — such as soil texture, compaction and organic matter — are relatively easy to measure quickly and accurately, whereas nutrients exist in parts per million, Lund says. Labs measure them with precise techniques too analytically complex to do on the fly. Yet real-time sensors might assess soil characteristics that influence nutrient distribution across a field.
Veris has a new tool, CoreScan, with sensors on a heavy-duty hydraulic probe. It covers 50 acres per hour, taking multiple probes per acre to provide rapid, in-depth analysis of compaction, water-holding capacity, topsoil depth, soil moisture, electrical conductivity, organic matter and carbon to a depth of 60 cm. CoreScan creates a field map farmers can use year after year.
Lund recommends sticking with the usual zone sampling and lab analysis for a few highly accurate soil nutrient results. Then, CoreScan infers soil nutrient patterns, accurately filling in the gaps between those lab-analyzed sample sites. The result is “removing the significant errors of over-application and under-application,” Lund says.
But this isn’t the low-cost easy button.
Still, CoreScan can be competitive with conventional methods in the first year, Lund says, and less expensive over a five-year period because of the reduced number of repeat sensor and lab samples required. Plus, he says, through machine-learning based on past samples, CoreScan can advance to create more accurate maps based on fewer lab-analyzed samples.
Cory Willness
Croptimistic
“I’m not going to disagree with this idea, but I don’t think it will happen in the next 20 years,” says Cory Willness, CEO of Croptimistic, the Saskatchewan company that created SWAT maps.
Accurate prescription mapping does take a lot of time and effort today.
Croptimistic’s prescription maps use soil, water and topography (SWAT) data from each field. Croptimistic staff collect this data ahead of time to set a baseline map for each field. Characteristics that influence yield and fertilizer response include soil texture, organic matter, topsoil depth and salinity, commonly dry or wet areas of a field, and landscape positions—hilltops, mid-slopes and depressions. Staff then typically sample five zones per field per year to assess nutrient reserves in each zone.
“A 10,000-acre farm spends $2 million a year on fertilizer and seed. They need a soli fertilizer and seed plan to optimize their inputs,” Willness says. “Croptimistic works with customers for three years to create the detailed dataset that forms the basis for why they do things.”
Willness does see a benefit in making the process easier. Croptimistic is working on an autonomous soil sampler and analytics process. No people. No lab. It would still be SWAT-map based, he says, but would cut down on the costs to collect more and better annual samples, and lead to better outcomes.
“But the autonomous sampler has to be cost-effective, or we’re not going to start,” Willness says.
Dale Koch
Precision Planting
“I think you’re on to something,” says Dale Koch, product manager at the Precision Planting research facility in Illinois. (Precision Planting is a division of AGCO.) “But on-the-go lab-accurate nutrient analysis is really hard.”
Koch lists the four components of fertilizer management: Collection of samples, lab analysis of samples, interpretation of analysis, and fertilizer application.
“The application tech is there. As an industry we’ve done a great job of coming up with tools that can do VR,” he says. “The other three steps have a lot of noise in them.”
This has a lot of farmers questioning whether the industry can write them the perfect VR prescription, Koch says. “For farmers, it doesn’t look like all upside. With VR, they see the risk that results will be worse than just using their flat rate.”
Precision Planting has one tool, SmartFirmer, that Koch says is a “simplified version of what you’re describing here.” SmartFirmer optical sensors operate in the seed furrow, measuring reflectivity of the soil at various wavelengths. These measurements are correlated to soil moisture and organic matter. Farmers can use these measurements as a proxy for mineralization potential. They could reduce nitrogen rates in soils with higher organic matter that can provide more nitrogen from mineralization.
“As we see it, farmers will spend the same amount on nitrogen fertilizer, but can be smarter about where they put it,” Koch says.
SmartFirmer is for planters with metering systems directly above the seed row opener. Each unit is about US$800, and Koch suggests at least three per seeding tool. (The tool is not at this time compatible with air seeders with meters typically many feet away at the air tank.)
Precision Planting has another project, called Radicle Lab, for faster in-the-field analysis of soil samples. The mini lab is not just a scanner but provides same-day results and loads them directly into a Radicle field map.
Koch thinks the world needs a more consistent soil analysis system. “Analysis is not as repeatable and accurate as it needs to be,” he says. Precision Planting wants to crowd-source its way to a better soil analysis system, and seeks farmers to participate in testing. “By connecting Radicle Lab soil test values to your yield response data from added fertilizer, you can help define the future of fertilizer recommendations,” radicle.ag says.
Conclusion
Okay, so we’re not close to a revolution in real-time on-the-go targeted variation in fertilizer rates. That could take decades. But we are evolving toward a more accurate and possibly cheaper and easier non-blanket system that farmers trust. Fertilizer rates are about best bets. We will never have sure bets, but right rates can get better. These companies are among those working on stepping stones to make the technology better.
