Testing with automated variable planting depth yields remarkable insights for corn growers

The trial took place in 2023, and the objective was to evaluate yield and economic performance of various manual corn planting depths consisting of 1 inch to 3 inches in ¼ inch increments, compared to automated variable depth planting using SmartDepth control.

Precision Planting emphasises that digging seeds is a time consuming yet important task at planting time. “Getting your eyes on the furrow where the seeds are placed will allow you to understand if those seeds are in an environment to thrive”, the company says. “Is the seed being planted in adequate moisture? Until now, we didn’t know this for every seed, and we were unfortunately simply guessing.”

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Evaluating furrow moisture in real-time.

The researchers say that the recommendation for ideal furrow moisture levels to achieve adequate corn emergence, is near 32%. Sensors and a monitor (In the trial the Precision Planting 20|20 monitor was used) give growers the ability to evaluate furrow moisture in real-time. Based on this real-time information, growers can make decisions based on live sensing data.

The SmartDepth technology allows planting depth to be changed on a planter, by section or individual row basis.This can be done manually from the tractor cab and a console, or automatically using furrow moisture values from sensors.

Customise settings

Growers can customise their own settings to optimise both furrow moisture and planting depth values. This control allows growers to measure, react, and take control of planting depth to optimise emergence timing.

The automated variable depth planting, using SmartDepth, achieved corn yield within 2.4 bushels per acre of the optimum planting depth of 2.25 inches and economic variance of only US $12.74 per acre. For the 2023 Yield Summary Data, the Precision Technology Institute calculated net returns calculated with corn prices of US $5.31 per bushel (25.40 kg).

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Deep planting depths were not needed

The telling story in this study is furrow moisture levels, the researchers point out. The average furrow moisture during the trial was 38.8% Currently, the recommendation for ideal furrow moisture levels to achieve adequate corn emergence is near 32%.

All planting depths deeper than 1.25 inch had furrow moisture over 32% . This indicated good field moisture and deep planting depths were not needed. At 1 inch, and 1.25 inch, planting depths lacked moisture, and that’s why there were big yield losses at those depths. With the new technology, the researchers were able to obtain perfect planting depths just below the furrow moisture line.

In another corn planting trial, the yield response of planting speeds of 4, 6, 8, and 10 MPH with a Precision Planting SpeedTube system was evaluated. This high-speed planting technology takes the place of conventional seed tubes and consists of a flighted belt. By transporting each seed to the furrow, there is no opportunity for seeds to ricochet into the trench. Even at twice normal planting speeds, seed arrives safely at the bottom of the trench, spaced evenly.

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Planting twice as fast

Multi year data from 2018 to 2023 shows that, with SpeedTube planting at speeds of 4, 6, 8, and 10 MPH, there was only a variation of 2.5 bushels per acre.

With traditional planting speeds typically near 5 mph, this data would suggest that growers could plant twice as fast without sacrificing planter performance. Being able to plant almost twice as fast would allow farmers to wait until planting conditions are perfect to plant, resulting in the best yields.

The Precision Technology Institute is also working on establishing solutions to help eliminate incorrect leaf orientation. Some of this work identifies seed placement in the seed furrow to manipulate direction of leaf placement.

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Leaf orientation

Early studies indicate that incorrect leaf orientation cannot be totally prevented, but trial data does suggest that placing seed in certain positions in the furrow can improve results by 10%. In general, seed tip directional placement has been seen to improve emergence timing, while embryo directional placement potentially may impact leaf orientation.

In a Corn Leaf Orientation Study, the Precision Technology Institute studied corn leaf orientation within the row, to understand the relationship of yield impact of corn leaves being positioned parallel or perpendicular to the row.

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^{Correct (left) and incorrect (right) leaf orientation. – Photo: Precision Planting}

The ‘all wrong’ planter study

Correct leaf orientation offers benefits of increased light interception, less sunlight to encourage weed suppression, cooler in-canopy temperatures, and moisture preservation.

Multi-year results of yield checks at the farm of the institute from 2018 to 2023 show individual ear weight loss associated with incorrect leaf orientation resulted in 8.92% yield loss. There were average yield losses of 17.8 to 22.3 bushels per acre.

However, occurrence factors of these incorrectly oriented plants generally range from 20% to 30% of all plant populations. Therefore, actual yield losses from incorrect orientation range from 3.6 to 6.7 bushels per acre, depending on overall actual corn yield average.

Economic effects

The Precision Technology Institute also looked at the effects on corn yield of ‘all wrong’ planter settings. This planter trial was designed to simulate yield and economic effects when a grower gets downforce, residue manager settings, and singulation incorrect on the planter, all at the same time.

For this study, the institute implemented light downforce, ‘goof’ plates to achieve 5% singulation, and removed the use of residue managers. The ‘all wrong’ planter settings caused average yield losses of 17.6 bushels per acre, and average economic losses of US-$96.47 per acre when all three planter settings were incorrect.

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^{The ‘all wrong’ planter settings caused average yield losses of 17.6 bushels per acre, and average economic losses of US-$96.47 per acre. – Infographic: Precision Technology Institute}