Corn Trial Will Test Basics of Planting Decisions

How much does speed, depth and downforce matter?

Tom Bechman

Published: Jun 2, 2010

You have heard for years that if you drive your planter too fast, its performance will slip. Those picket fence stands will elude you. You've also heard debated since you were probably a young boy how deep corn should be planted. And more recently as minimum tillage and no-till have become more popular more people are talking about how much downforce should be placed on the planting units. To get a handle on all these questions, Indiana Prairie Farmer, the Purdue University Extension Service of Tippecanoe County and the Throckmorton Purdue Ag Center decided to collaborate on a replicated research trial to search for answers. Precision Planting, Tremont, Ill., is sponsoring this trial.

Since heavy rains in the Lafayette area delayed planting, the plot was finally planted in reasonably good conditions on Thursday, May 27. The corn follows soybean stubble, worked the day before in conventional tillage with little or no residue left on the surface. . By planting time, it was dry on top, but there was still moisture, likely enough for germination, at least at the deeper depths, underneath the surface.

Jeff Phillips, Tippecanoe County Extension Ag educator, helped set up the design for the experiment. Altogether, three planting speeds, three planting depths, and three amounts of downforce on the planting units were tested. The plot was planted with a six-row John Deere, Max-Emerge II Vacuum planter. Seed was provided by 1st Choice Seeds, Milton. The hybrid, selected by Dave Nanda, a crops consultant , Indianapolis, was a Liberty Link hybrid that represents elite genetics. Other than Liberty Link, it does not possess other GMO traits. Ignite will be used for weed control over the top as necessary. A soil-applied insecticide was used on the plot since the corn did not possess the rootworm resistant trait. Nanda has been an advocate on non-GMO hybrids, and although this one is Liberty Link, it does not contain the complete stack that supplies resistance to both rootworm and European corn borer.

Three speeds, 4, 5 and 6 miles per hour were used as the speeds. Many people plant at 4.5 to 5.5 miles per hour, so these speeds were selected to help establish speed boundaries. Planting depths were one, two and three inches. Several farmers tried planting deeper this spring, observers note. This experiment will help determine how it fares under a test condition, planted May 27.

Downforce pressure consisted of a relatively light setting, second to the lowest pressure setting on the Deere planter model, an average setting, typically used on the farm, and a heavy downforce pressure- the heaviest possible on this planter. The goal is to see how these combinations combine to either provide the perfect environment for even and uniform emergence, or else which combinations are most likely to product problems.

Many early measurements will be taken and the soil temperature at various depths will be recorded. The plots will be carried to yield, and results will be reported here and in Indiana Prairie Farmer in an early winter issue.