Row By Row / October 2018

Top Three Reasons for Harvest Loss at the Corn Head

University research has shown that 60% of yield loss occurs at the corn head itself. There are many factors that can be attributed to this loss – and many of them are related when one problem leads to another, according to Fenton, Iowa farmer and Dragotec President, Denny Bollig.

Downed Corn.

Downed corn is one of the greatest fears for producers at harvest, Bollig notes. “All the sins of the growing season show up at harvest. Excessive moisture can force us to till and plant in conditions that are not ideal, impairing root development from tillage and sidewall compaction. Combine that with plant disease, insect problems and wind storms and your chances for down corn increase dramatically.”

The location of gathering chains and their ability to grab and gather leaning stalks are crucial in picking up downed corn. Bollig points out that Drago gathering chains, by comparison to other brands, are located out-front and overlap to grab and secure stalks. “And Drago choppers are positioned behind the knife rollers to avoid striking leaning plants, which can prematurely drop ears before plants can be processed.”

Misadjusted Deck Plates.

Kernel loss at the deck plates can be a significant source of yield loss at harvest, Bollig says. He points to Iowa State University research that shows a deck plate gap as little as a one-eighth of an inch wider than required can mean up to a 4 bu./acre loss in the field.* “Because of plant variability and limited visibility, it’s really impossible to accurately set deck plates from a combine cab at harvest,” he points out. “Operators can’t see when deck plates are set too wide, and when the deck plate gap is too tight, excessive plant material is run through the combine, causing yield loss there. He points out that Drago corn heads avoid the entire problem with independent, self-adjusting deck plates that automatically minimize gaps – “both in-row and row-to-row.”

Knife Roller Speed.

Early season – “Harvest is a violent process,” Bollig says. “And early in the harvest season, higher-moisture ears can bounce off deck plates because of the excessive speed when being pulled down too fast.” Along with being longer than those of other brands, Drago knife rollers are designed to process plants their entire length, he notes. “This allows knife rollers to run at a slower speed, reducing the velocity of ear impact – and ear bounce – off deck plates.”

Late season – With today’s fast dry-down hybrid genetics, potential yield loss changes from ear bounce in early season, to butt shelling as kernels dry due to excessive knife roller speed and stalk pull-down. “Dry ears have built-in shock absorbers – they’re called kernels,” Bollig jokes. Upon impact those dry kernels shell and can be lost. He points out that the Drago GT corn head is specifically designed to minimize ear impact and resulting in less butt shelling with the introduction of ear-shocks positioned under each deck plate. “The GT’s integrated ear shocks absorb much of the impact of ears striking deck plates, reducing both ear bounce as well as kernel loss.”

Choosing The Right Corn Head

“The ability of a corn head to reduce loss at harvest has a lot to do with the genetics producers choose at planting,” says Bollig. “As farmers, we balance traits like faster dry down, ear retention and standability with potential yield. Plus, we are continually pushing plant populations to get more yield. The result is that we risk plant vulnerability to weak stands, kernel loss with fast dry down, smaller ears – which can slip through deck plates – with high populations and yield loss simply through the volume of material the corn head and combine must process.

“Producers shouldn’t change their genetics and sacrifice higher yields due to concerns of higher loss, but they should consider owning a corn head that can compensate for the potential issues their genetics bring.”

*Graeme Quick field research, Iowa State University.