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How to Avoid Yield Loss Using Curve Compensation

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Planting is often considered the most important step in a farming operation. For this reason, there have been many advancements in planter technology that allow farmers to work more efficiently. For example, one strategy often used by growers is employing larger tractors and planters to cover more ground. However, larger planters come with their own challenges, such as the inconsistency in seeding rate that can happen across the rows when a planter drives along a curve.

Planting on a Curve
To help visualize, picture a marching band in a parade. As the formation approaches a turn, those on the inside virtually march in place while those on the outside speed up to give the illusion that they are turning in sync. If they did not do this and everyone marched at the same pace, those that were on the inside of the curve would be noticeably ahead of the others.

While one might think a planter has nothing in common with a marching band, the way they navigate around curves is similar, with the outside rows moving faster to keep up with the inside. This leads to the inconsistency in seeing rate. When seeds are dropped at a constant rate among all rows, the inside rows become greatly overpopulated because the row unit didn’t travel very far. Meanwhile, the outside rows experience under-population because the row units traveled a greater distance between seeds.

The good news for growers is manufacturers are beginning to address this issue. Curve compensation is a feature offered on newer electric-drive planters, such as John Deere’s Exact Emerge and Max Emerge 5e row units. The electric motors on each row unit allow them to operate independently of each other, so a different seeding rate can be run on each unit across the planter. While most planters today can execute a variable rate prescription, it is implemented as an average rate across the width of the planter. As a result, when planting in a curve, the row units on the outside of the planter speed up, and the row units on the inside slow down, decreasing the difference in seeding along both sides and effectively solving the problem.

Studying the Curve
Because curve compensation is a new feature, the team at RDO Equipment Co. sought to study it and show the potential yield loss that can occur without it. Daniel Eslinger and Brent Horner, members of the product specialist team in North Dakota, decided to evaluate a customer’s field.

“Not every field is square and we were curious how plant populations were affected by a curve,” Eslinger said. He further explained that the primary goal in conducting the study wasn’t to show how well curve compensation works but, rather, to determine what kind of yield loss could be expected without it.

Horner and Eslinger took stand counts across the width of 24 planted rows and followed the area through the season. In their preliminary stand count they found that the inside rows were overplanted by up to 124% of the target population while the outside rows were only at 81% of the target population. It’s conceivable that on a larger planter, such as a 36- or 48-row, this disparity between the outside and inside rows would be even larger.

When it came to time to harvest the ears, Eslinger explained the team’s initial observations and conclusions.

“On the outside rows, where we had thin population, the cobs were massive, but we still had lower yield,” he said. He determined this was because the plants had access to more resources such as water, nutrients, and light, but they were not able to compensate for the lower plant population. The center rows had an average yield of 161 bushels per acre (bu/ac) while the inner and outer rows yielded 152 bu/ac and 131 bu/ac respectively. With $3 per bushel of corn, this represented a $27 loss per acre on the inside rows and a $90 loss per acre on the outside rows.

In a field with a lot of curves, this degree of loss can add up quickly, curve compensation technology offered in many new planters could easily pay for itself. However, it’s important to note that, while clear benefits exist, this technology isn’t for everybody.

“You have to think of a customer’s field and how many curves they’re going around,” Eslinger said. With thoughtful evaluation of a grower’s unique business, moving to the technology found in the MaxEmerge 5e and ExactEmerge row units would be a good decision for some. 

Applying the Curve
In addition to the technology offered by these machines, the ExactEmerge system is designed for such accuracy that variable rate prescriptions and curve compensation can be reliably implemented at speeds up to 10 mph, offering several benefits for farmers in terms of input costs, efficiency, and yield.

Eslinger and Horner hope to continue evaluating curve compensation, and turned to the sales team at RDO Equipment Co. for additional thoughts on potential future trials. Included in the ideas that would provide valuable information for them and their customers were performing side-by-side comparisons of different row units, the effectiveness of prescriptions, and looking at different row spacing.

For those thinking about conducting field trials of their own, Eslinger and Horner advise to remember to keep it simple. It’s typically recommended that only one or two things be compared at a time, otherwise there can be too many variables, making it difficult to draw accurate conclusions. Also, don’t forget about the growers. Pick trial ideas that will provide valuable information for growers looking to improve their operations.

When visiting their customer after the curve compensation trial, Horner and Eslinger said he could certainly see how a planter with curve compensation could improve his yield.

“Now, are we going to sell him a new planter because of it? I don’t know,” Horner said. “But it’s possible!”

Both Eslinger and Horner hope this field trial and others they plan to implement from their list of new ideas will provide helpful information for growers in their area to think about, and concrete numbers for sales team members to use when talking about new technology with their customers.

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About the Author
Nate Dorsey is an Agronomist for RDO Equipment Co. based in Moorhead, MN. Connect with him on Twitter @RDONateDorsey.

To learn more about curve compensation and the benefits it could offer your operation, contact your local RDO Equipment Co. store.

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