Optimum rate

Variable rate (VR), as a phrase, is thoroughly uninspiring. Boring. People want to hear about VR about as much as they want to hear about the 50-year-old wool suit I bought at Value Village for $22. I see that now. But optimum rate! That inspires.

In October, I wrote a LinkedIn post about a breakfast conversation I had with Blake Weiseth, who runs Discovery Farm at the Ag In Motion site west of Saskatoon.

“Variable rate is sexy, but it’s not the next logical step for a lot of farmers,” Weiseth said at breakfast. “For many farmers, using a fertilizer blend and rate appropriate for each field is their next step to more precise nutrient management. With field-to-field variability sorted, then let’s tackle in-field variability.”

I shared this quote on LinkedIn and asked, should precision ag advancement follow a step by step path? Or can farms skip from (a) one fertilizer blend and rate for all canola or wheat or pea fields to (c) precise management of zones within each field? This would leap past the middle step of (b) a fertilizer blend and rate appropriate for each field.

The responses were varied and insightful, founded largely on farm and agronomy experience.

Wes Anderson, vice president of agronomy at Croptimistic Technology, wrote that we tend to see a lot more variability within fields versus between fields. His point, and I’m paraphrasing, is that a composite sample from one field might be similar to a composite from the next field on the same farm, so those fields would get the same blend at the same rate. But he says this covers up fairly large differences within fields that could be managed more effectively.

To that Weiseth responded: “Good point regarding the relatively small difference in field to field variability when two fields are close together and managed similarly. I’m thinking of field-to-field at a fairly macro-level, where on a single farm, there could be fields of different ag capability class, parent material, management history, etc.”

Anderson replied, “Your comments aren’t wrong. Measuring and treating each field could be a step in the right direction for some farms. But I feel as industry professionals, we need to strive for more advanced levels of 4R. If we don’t raise the bar for management level, who will?”

Merle Massie, executive director for the Do More Ag Foundation, added that pressures of seeding don’t always allow for all of this variation. “The time needed to change up fertilizer blends for each field or within each field is often sacrificed for time and efficiency reasons,” Massie wrote.

“This aspect of seeding limitations deserves more understanding.”

Nevin Rosaasen, sustainability and government relations lead with Alberta Pulse Growers, echoed that thought: “Whether it is the first step to soil sampling, or running full VR, every farm business manager needs to balance the agronomics, economics and logistics for their farm. There is not a single solution,” he wrote. “Any farmer who tells you ‘my way is the right way’ has perhaps solved the equation for their field or farm, but it may not be the correct solution for their neighbour.”

This is all from one LinkedIn thread. Agronomy gold. And it kept going.
To the point about the overwhelming and logistically near-impossible problem of a blend for each field, Rob Saik jumped in with the solution: don’t buy blends.

Saik, the well-known agronomist and entrepreneur, CEO of T1 Technology Corporation, noted that air tanks with four or more compartments will do the blending for you. A tank with four compartments could have a starter blend that included the phosphate, then run nitrogen, potassium and seed in the other three tanks. Sulphur could go on in a separate pass. “As farmers adopt more and more variable rate technology, they move more and more straight product,” Saik added in a follow up text.

In the farmer panel in this issue, Andrea De Roo talks about doing just that. Her farm bought a bigger air drill tank to carry urea, potash, monoammonium phosphate and seed in separate compartments. No more blends. The farm applies sulphur in a separate pass as BioSul or elemental.

The last word goes to Wes Anderson.

“We need to stop looking at VR as just varying rates, and start looking at it as an investment of knowledge in fully understanding the breadth of nutrient response probability,” Anderson wrote in the LinkedIn thread.

“The goal isn’t varying rates, the goal is optimum rates – in every part of the field. If we never map and measure that, we won’t see the progress we could have and frankly need to achieve for future social license.”