SASKATOON – Farmers interested in precision farming are encouraged to approach the subject using hand grenades, shotguns and laser-guided missiles.
“One of the problems with precision agriculture is the dots being connected have no business being connected,” said Elston Solberg, a senior consultant with Agri-Trend.
“Plants grow from the roots up and that’s where I think we should start. We need to prioritize the field limitations.”
Each field has different limitations and simply assuming it needs nitrogen and then applying variable rate nitrogen over the whole field doesn’t make sense, he said.
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“We need to do a serious soil audit, then figure out which fish we need to fry first.”
With the advent of yield monitors, Solberg said yield variability across a field can now be easily documented. Fields that averaged 52 bushels per acre can have yields that range from less than 20 to more than 75 bu. per acre.
“Farmers ask, ‘Why can I grow 75 bu. here and only 20 bu. there?’ You have anywhere from a two to four-fold yield difference across the field. That tells you there’s lots of variability and lots of issues. I don’t think it can be boiled down to just variable rate nitrogen.”
“How can we even out yields across these fields? One of the ways we can do that is use a hand grenade approach,” Solberg said.
“It doesn’t necessarily need any variable rate technology, or it might not need any technology at all. It might be something as simple as a Valmar or a spin spreader. It’s basically isolating fields that need a shock treatment, with amendments that will not cause significant harm if there’s overlaps.”
Products could include lime, wood ash, potassium, copper, manure or compost, which Solberg called precision agriculture hand grenades. But how do producers use them?
“If you want to increase the pH of a soil one unit, that’s going to take between 1.5 to three tonnes of lime or wood ash per acre and cost between $60 and $120 per acre,” he said.
“That’s a lot of money, but it’s going to last at least 10 years. If you put this stuff in the right place and do a good job, it’s going to give you a long lasting effect.”
Solberg suggested the hand grenade approach – use site specific sampling, identify the areas most affected, isolate those areas, apply the material to the 40 percent of the field that’s affected and at the end of the day, the average cost across the field is $40 per acre rather than $120 per acre.
He said some jurisdictions restrict phosphorus application if soil test levels are above a certain level. By identifying specific areas low in phosphorus, manure can be applied to fix the problem, while still complying with the jurisdiction’s legislation.
“It’s another kind of hand grenade.”
Base saturation of potash is a nutrient measurement determined when soil testing. Solberg said the optimum level is between three and five percent base saturation of potash.
“If a field is highly variable, you can identify areas to put on 100 to 300 pounds of potash and have a dramatic impact on the productivity of that field. And banding is better than broadcasting,” he said.
Copper is another good example, he said. Typically, copper levels increase with soil depth. If subsoil levels are lower than the topsoil, the response to a copper application is good. But if the copper level goes up in the subsoil, response to additional copper goes down.
Solberg said shotgun situations are fields that need a general or balanced application of an amendment to elevate overall productivity.
“Variable rate capability is often not required here, but it can be useful in some cases. Generally speaking, we’re talking about broadcasted fertilizers or amendments, and for some, balanced fertility.”
Fields that need a specific variable rate application to improve their overall productivity require laser guided missiles, he said.
“Nitrogen is probably the best example, but micronutrients are another example.”
Solberg said this approach is starting to make more sense as technology improves.
“If you’ve got good information and you know what you’re doing, laser guided missile works really well. Technology like Greenseeker is a way to get variable rate application. The whole idea is to gather as much information as possible to determine which issues need to be solved and in what manner,” he said.
Solberg said images, soil survey and yield maps and data from soil samples are just a few of the places where producers can get started.
“Too many of us think we’re growing leaves and grain above ground and forget about the roots below the ground. We’re actually growing roots. If you can grow roots, you can grow the rest of it,” he said.
“So layer in as much information as possible, then compile that information to create zones. Once a field is zoned, simple monitoring and referencing (may be all that’s required) from that point on. If you do grid or site specific sampling once, then in future years you only have to go in and sample the odd zone to confirm what it is you learned the first time.”
Objectives may include moving the yield curve up and narrowing the variability across fields.
“It’s going to cost somewhere in the range of $7 to $15 per acre, depending on how you do it. But at the end of the day, if you can determine that only 40 percent of your field needs (a specific treatment), you can correct that area of the field and that lasts for 10 years or more, the cost efficiency of that is very powerful,” he said.
“We’re thinking that in many cases, if you do a good job of this, you’ll have to do it very few times in your entire farming career.”
Solberg said each farmer has fields that require a hand grenade or a shotgun. Fields might need a shotgun approach for pH or phosphorus, or a hand grenade for micronutrients and areas that could benefit from laser guided variable rate applications such as nitrogen.
“To assume you can go in and be a variable rate guy, with one or two nutrients based on one or two measurements and that’s going to apply to your whole farm, doesn’t make any sense to me,” he said.
