No matter how high-tech potato harvesters and windrowers become, they’ll always depend on one seemingly low-tech component — the digging blade. But, don’t make the mistake of brushing off the blade as unimportant. In fact, your blade really does make the machine.
There are six blade types available, each designed for specific harvest conditions.
In sandy, light soils, opt for a semi-point blade, which can include an optional plastic rock guard fitted between the blade and primary digging chain.
In heavier, somewhat clod-prone soils, opt for a combo blade, which features a blunt, dished edge to break up clods. Producers with varying soil types often choose this versatile blade.
In very heavy, highly clod-prone soils, producers fare best with a clod blade. This blade features a blunt edge to break up clods and a narrow blade surface to improve flow.
About five years ago, manufacturers unveiled a semi-clod blade. As the name suggests, the blade is a combination of a semi-point and a clod blade: it offers more surface like a semi-point, but a blunt edge for tackling some clods.
Potatoes grown above a lava rock shelf are sometimes still harvested with a shallow, blunt-tipped lava blade, designed to skate over rock. Because blade depth control has improved so much, however, a lava-specific blade is no longer as necessary.
While most producers still plant in rows of between 32” and 36” spacing, some producers have shifted to bed style planting with very narrow spacing instead. For that production system, producers typically opt for a flat, full-length bed blade.
To get the most longevity from your investment, opt for abrasion resistant, high-strength steel rather than chrome-plating blades or hard surfacing. Both bed and semi-point blades offer bolt-on plates that can be replaced when worn.
While having the right blade is key to managing harvest in your soil type, optimizing your blade depth can make just as much (and sometimes more) difference. To minimize soil and clod management, a blade needs to dig at the ‘sweet spot’ depth — deep enough not to cut tubers but shallow enough not to pull up clods and excessive dirt.
Remember too that speed helps flow. I often find that producers testing new machines will start digging very slowly – much slower than they’d operate under real harvest conditions — and then be disappointed both by how the blade digs and the conveyor feeds. In fact, you’re doing a new machine no favours by trying it out at slow speed, as the blade needs adequate soil momentum and the conveyor needs enough bulk to operate optimally.
Harvest will be here sooner than you think!