Of all the things you worry about on the corn planter, or at least have traditionally, how much downforce you're getting on the row units from the gauge wheels around the seed opener discs probably isn't at the top of your list of concerns. Results from a seed company study and resulting comments indicate that maybe it's a factor worth paying more attention to.
Beck's Hybrids conducts Practical Farm Research studies. These demonstration plots are conducted at Atlanta, Ind., near Ft, Branch in southwest Indiana, and also near Lexington in central Illinois. At the Illinois site in '09, one study compared down force on the planter units. Every other factor was kept the same.
The study included no down pressure, which is one extreme, and 375 pounds of downforce, which is another extreme. One will leave the seed too shallow. The other is likely to produce soil compaction on the sidewalls of the planting slots. When that happens, the 'hatchet root' effect is common. Roots end up going sideways trying to find a way out of the micro-environment they find themselves in due to compacted sidewalls in the planting trench.
The study also included two more moderate rates of downforce, 125 pounds of pressure, and 250 pounds. And it also included an automatic downforce control system marketed by Precision Planting, Tremont, Illinois. It's called Air Force. The entire purpose of this option on a planter is to control the downforce on the planter units automatically, using air pressure that regulates the inflation or deflation of two small bags on each unit, a down bag and an up bag. These bags replace traditional springs on many planters. The pressure is adjusted automatically to a preset pressure range selected by the operator. As conditions change, the unit interprets the average readings from all row units, and adjusts the pressure if necessary. It even adjusts downforce as you plant out seed and/or fertilizer, from full to empty.
The study was carried to yield. The result was a 9 bushel increase from zero pressure, or from 250 pounds, for the 125 pound setting and the Air Force automatic downforce control system. The Air Force system and the 125 pound constant setting yielded within a bushel of each other.
Beck's staff interpreting the results concluded that not having proper downforce on planter units, whether you do it by checking and changing pressure manually, or by having an automatic system, can cost you $32 to $52 per acre in lost yield. The highest number represents the extreme case of 375 pounds of pressure.
Precision Planting has similar studies out again this year. With the wet weather that developed, it's possible that downforce could be another extremely important variable this year.