Does variable-rate seeding pay?

John Horter, Andover, S.D., is going to be varying corn seeding and fertilizer rates again this spring.

He’s varied seeding rates for a couple of years on his northeast South Dakota farm and figures the practice is making and saving him money.

Horter’s cropland is rolling and includes highly productive low areas (when there isn’t too much water) and poorer-producing eroded hilltops. He used to set his corn planter at 29,000 to 30,000 seeds per acre and plant all his corn at same rate. But, after creating management zones from satellite images and soil and yield maps, and purchasing a new planter with a variable-rate hydraulic drive, he’s been varying the seeding rate from 24,000 to 36,000 seeds per acre to better match the yield potential of different management zones. He also varies fertilizer rates by the management zone.

“I think it’s paying off,” Horter says.

The most noticeable difference in yield and profits has come on the eroded hilltops, where he cut the seeding rate from 30,000 seed per acre to 24,000 seeds per acre. He says data collected by the yield monitor shows that yields have increased by 20 to 30 bushels per acre compared to previous years, and — in some places — by as much as 50 bushels per acre.

The low areas of the field, which are usually the most productive, haven’t shown a clear response to the higher seeding rates. Horter says that may be because it’s been so wet recently that the soil in the low areas doesn’t drain adequately to maximize yields.

Key Points

Farmer has success with varying corn seeding rates.

Reducing plant populations on hilltops has paid off.

It’s not clear whether the practice pays in all situations.


Horter also is using automatic row clutches on each opener to shut off the seed when the planter reaches areas that have already been planted. It’s saved him seed and yield on headlands and angle rows.

“I have a lot of angle rows with all the wetlands we farm around,” he says. “It doesn’t take long to pay for the row clutches.”

Anthony Bjerke, president of AgTech, Webster, S.D., has been helping Horter and other northeast South Dakota corn growers with variable-rate seeding and fertilizer applications.

“I’m seeing 8-to-10-bushels-per-acre increases with variable-rate seeding,” Bjerke says. “The biggest yield bump is coming from seeding prescriptions that are tailored to the variety being planted.”

More research

South Dakota State University and North Dakota State University are conducting research to come up with scientifically based recommendations on seeding rates.

“The interaction between corn, soil, fertilizer and the weather is extremely complex, making it difficult to scientifically predict yield increases from variable-rate planting,” says Kurt Reitsma, South Dakota State University Extension precision farming specialist, Sioux Falls. A planting rate that seems to result in a yield increase one year may not produce the same increase the next year. However, in some fields, the opposite may be true.

Dave Franzen, North Dakota State University soil specialist, who has worked extensively with variable-rate technologies, says “growers should investigate all parts of the planting process; make sure that seed spacing is as uniform as possible, as well as be able to vary seeding rates.”

In fields with irregular external or internal boundaries, the planter box shut-offs can be of great benefit in both saving seed and optimizing yield.

He encourages growers to work with their seed suppliers when varying seeding rates to marry variety population traits with soil characteristics.

Companies are working on harvest stand counters on combines that can show growers where soils with emergence issues might be found.

“Once these areas are documented, producers might reasonably expect a return on variable-rate corn seeding,” he says.

SDSU explores variable-rate seeding

South Dakota State University agronomists are planning to conduct some significant variable-rate seeding research this year. Kurt Reitsma, SDSU Extension field precision farming farm specialist, Sioux Falls, submitted this description of the research:

“The goal of the variable-rate seeding research this year will be to collect data for validation and development of optimization curves and determine differences in optimization curves between study sites. The results from this multiyear project will help to improve optimization algorithms for improved variable-rate seeding recommendations.

“The research currently under way is part of on-going on-farm research being conducted at SDSU by Drs. David Clay, Gregg Carlson, Cheryl Reese, Sharon Clay and myself. These scientists have dedicated the majority of their career in developing methods and practices for precision agriculture. The research and development of precision agriculture in South Dakota is a public-private partnership that has been and continues to be a collaborative approach including scientists from across the world. Dr. Carlson’s approach for developing recommendation algorithms can change the way research is done. Dr. Sharon Clay’s award-winning research (paper of the year by the Weed Science Society) on understanding the causes of yield variability can lead to solutions that we never anticipated. Dr. David Clay’s research on the use of stable C and N isotopes is changing our understanding of yield response functions. Dr. Cheryl Reese’s research on investigating stress impacts on wheat quality can add value to every bushel of wheat grown and sold. Research is the means for gaining knowledge. Knowledge from research leads to the development of equipment, tools and recommended practices proven to work.

“The knowledge gained from research is key to education, training the next generation of scientists, agronomists, engineers, and others in agriculture.”


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PLANTER READY: John Horter makes sure his planter is in top condition before the planting season begins.

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MONEY MAKER: John Horter says using variable-rate seeding with corn has paid dividends on his farm.

This article published in the April, 2012 edition of DAKOTA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2012.