A new cereal harvester with no threshing equipment has been working in Oregon wheat fields this summer. Mark Siemen’s revolutionary Gleaner features no cutterbar, drums, concave or straw walkers.

The harvester, devised by Mr Siemens and his team at the US Department of Agriculture’s (USDA) Columbia Plateau Conservation Research Center simply strips the heads of standing wheat with a standard Shelbourne Reynolds stripper header and conveys the unthreshed ears into a giant hopper behind the cab – a container which takes-up the entire space formerly occupied by the threshing mechanism.

Stripper harvester

6.5kph (4mph) harvesting speed Weed seed removed from field Low power requirement Reduced fuel use Threshing system at store Grain separation to meet quality parameters

Right behind the 3.7m (12ft) stripper header is a similar-width flail topper which chops straw down to around 5cm (2in) above ground level. Mr Siemens says this leaves an improved surface for direct drilling the next crop compared with the usual long and uneven stubble after conventional combining.

In fact the movement towards input-saving low- and no-till systems on the central wheat plains of Oregon was one of the main reasons for the development of the new harvesting system.

The next stage in this simple system features a relatively inexpensive, low-power static threshing system back at the grain store. This set-up could handle the output from several stripper harvesters or even a fleet working several farms, according to Mr Siemens.

Not even the barn-based threshing system is conventional: It’s true that the grain first goes through a concave. But after that segregation of small and broken grains is via a so-called fluidised bed separation system.

Here, the grain is rapidly and accurately separated over an upward moving air-stream that can be adjusted for precise segregation of different densities of grains.

Last harvest the team used the set-up to re-grade a batch of wheat that had been down-priced because shrunken and broken grains in the sample.

The result after fluidised bed separation was that 80% of the batch moved into a top quality grade with virtually all broken grains dressed out. Mark Siemens says that work is now continuing towards aligning density with other grain properties such as protein content for even more precise grading capability.

A low power requirement is a key feature of the prototype Deutz-Allis Gleaner-based harvester says Siemens. With the stripper and flail mower in action the machine uses a steady 55hp and moves across the field at just over 6.5kph (4mph).

One problem is the bulk taken up by the unthreshed grain ears. The density during the trials was barely 8% of threshed grain so the team are currently working on a compressing system to help pack more heads into the harvester hopper. No economic evaluations have been made to date but the almost perfect no-till seed surface left in the fields already offered important time savings during last year’s trials.

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