Question of the Week
Answer: The mechanical roller-crimper is a tool that "rolls down" and "crimps" the stalks of cover crops for no-till weed suppression. Mechanical suppression of cover crops for no-till production can be accomplished through various kinds of mow-down and rolling/slicing/crimping techniques. These non-chemical methods of killing cover crops are appealing as an alternative to chemical-kill methods which rely on the use of synthetic herbicides.
The roller-crimper is a water-filled, heavy, round drum with protruding blunt metal blades arranged in horizontal, angled, or spiral patterns. Roller-crimpers are most commonly rear-mounted and pulled behind a tractor or team of draft animals, but they can also be front-mounted on a tractor. When the roller-crimper is pulled or pushed through a high biomass cover crop—such as wheat, rye, oats or oilseed radish—the cover crop is flattened and “crimped” by the heavy drum with metal strips. The purpose of the metal strips is to crimp or crush the stems of the cover crop rather than cutting or chopping the stems; this simultaneously prevents re-sprouting and slows down decomposition of the no-till mulch. No-till crops are seeded or transplanted in the same direction of the flattened and crimped cover crop, which slowly senesces and dies out over the course of several weeks, leaving high residue no-till mulch.
However, weeds that emerge in the no-till mulch can be a problem. In conventional no-till production herbicides can be used as a post-emerge treatment so weed control is fairly straightforward. In organic farming special attention needs to be paid to a clean field, excellent establishment of a winter annual cover crop, and high biomass cover crop production. Spot treatment of weeds is feasible with a hand-held flame weeder or with the use of organically approved natural herbicides on small acreages, but these labor-intensive treatments aren’t practical in broadscale crop production.
The drums are designed to be filled with water for added weight. The amount of water added varies depending on the size of the roller as well as the field conditions it will be used on. In other words, different field conditions will require different amounts of added weight.
The timing of the roller-crimper field operation is critical to gain effective kill of the cover crop. Cereal-based cover crops should rolled at the “anthesis” (flowering) stage of growth or later—in the milk or soft dough stages of growth, a period which corresponds to the mid-spring planting season shortly after the last frost-free day. Growers can refer to charts published by the Extension Service on the Feekes or Zadoks scale of crop growth to gain a clear understanding when anthesis, milk, and soft dough stages occurs.
The Rodale Institute in Kutztown, PA, has spearheaded research on roller-crimper equipment designs and on-farm trials using roll-down, no-till organic production systems. Research at the Rodale Institute finds that the best results are achieved by placing the roller on the front end of the tractor while a no-till seeder is simultaneously located on the back of the tractor. This enables a “one pass” roll-down/no-till planting system. They have found that in an organic no-till system, they do actually have to till once every five to six years to reduce weed populations.
The Rodale Research Institute has published several noteworthy articles and updates on their roller-crimper research project, including photos which are all located on their website. This site also contains AutoCAD drawings of their design.
The following resources can provide additional information on this topic.
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