The one-pass harvester strips wheat heads and carries them to a stationary machine for threshing. Click for detailed view.

Going against the Grain: A New Take on Harvesting

By Laura McGinnis
December 22, 2005

A wheat-harvesting system that could save farmers money has been developed by an Agricultural Research Service (ARS) scientist.

Today's farmers use a wheat-harvesting combine that cuts, threshes and cleans the wheat. Now ARS agricultural engineer Mark Siemens is investigating the benefits of using two machines to accomplish these tasks: a simple, low-cost harvester, and a stationary thresher.

Instead of cutting wheat in the same way as a combine, Siemens's harvester strips the wheat heads and stores them in a bulk tank, and then chops the standing residue into small bits. The stationary thresher separates the wheat from the chaff. Siemens is studying the economic potential of segregating wheat with a fluidized bed, which separates solid materials according to density. Preliminary studies suggest this segregation process increases the consistency of grain quality, particularly with the soft white wheat used in pastries, cakes and cookies.

The modern combine found on almost all U.S. farms can harvest, thresh, separate and clean, but the expensive mechanisms that perform these operations can bring the price to $250,000. The components of Siemens's system are much less expensive, and one thresher could serve multiple farms, significantly lowering overall production costs.

Siemens's system also eliminates many of the problems associated with stubble, the straw stems that remain in the field after harvesting. A typical combine cuts wheat about 16" above the ground, but lacks a mechanism to chop the remaining stubble, which can impede subsequent farm operations. Common management practices—like flailing, burning and baling the residue—are expensive and time-consuming. The field residue also can impede the performance of seed planting drills and inhibit seedling growth.

The one-pass harvester includes a flail mower to reduce stubble into small bits that are less likely to plug seed drills or concentrate in seedling-choking piles. Siemens and his colleagues are currently investigating how to improve the system's economic and time-saving benefits.

This research was conducted at the ARS Columbia Plateau Conservation Research Center in Pendleton, Ore.

ARS is the U.S. Department of Agriculture's chief scientific research agency.