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A Makeover for Roller-Crimpers
As the number of acres planted to cover crops across the country grows by leaps and bounds, so does farmers’ demand for innovative ways to terminate the cover crops before planting cash crops.
Terminating cover crops by mechanical rolling-crimping is one alternative technology proving its worth at the USDA-ARS National Soil Dynamics Laboratory (NSDL). The technology for rolling-crimping has been around for a while, but it’s getting a makeover as new, patented designs of roller-crimpers come to life at the laboratory. The new models offer greater operational ease and flexibility.
Traditional rolling-crimping machines are typically designed so that a weighted roller flattens the crop. Commonly, straight-bar crimping elements fixed to the roller rupture the stems of the cover crop so that termination of the plants is complete in two to three weeks.
In one NSDL study, a straight-bar roller-crimper achieved a 96% termination of a cover crop two weeks after rolling without the use of herbicides.
“The main objective is the flattening of the cover crop to create a protective layer of residue on the soil surface,” says NSDL engineer Ted Kornecki. “We can plant cash crops directly into the residue cover. The mat of residue protects the soil from water erosion and also acts like a mulch, preventing moisture loss through evaporation. The residue also adds carbon to the soil.”
Rolling Along Doesn’t Kill Crop
However, simply rolling the cover crop flat won’t terminate the plants. Hence, the crimping process is needed to damage the stems so the plants die.
A problem with original designs of straight-bar crimpers is that they vibrate at increased operating speeds. The vibration causes wear and tear on machine components and also transfers undue vibration to the tractor. “To reduce excessive vibration, producers must decrease roller speed, which increases the time for rolling cover crops,” says Kornecki.
To resolve this mechanical shortcoming, Kornecki designed and patented a two-stage roller-crimper with two drums. “The first drum flattens the cover crop, and the second drum with crimping bars crimps the cover crop,” he says. “The second drum is isolated from the first drum to minimize vibrations. It’s preloaded by two compression springs for which the crimping force can be adjusted by screws. It can be configured in single or multiple sections to accommodate farm size and the size of available tractors.”
At a farmer’s request, Kornecki expanded the design of the two-stage roller into a four-stage model. With this design, three crimping drums follow the smooth roller drum. The additional crimping drums achieve effective termination of exceptionally heavy cover crops and decrease the time it takes for the cover crop to be terminated.
“One pass of the four-stage roller is equal to three passes of the two-stage roller over the same cover crop area,” says Kornecki.
In both models, which have a three-point hitch attachment, vibration is no longer an issue. “I have operated the machines at 10 mph in the field and noticed no vibration that would cause structural problems on the machine or on the tractor,” he says.
To provide farmers with a roller-crimper of significant width, Kornecki is in the process of designing attachment mechanisms that would permit the operation of a 30-foot-wide machine comprising three independent, 10-foot-wide sections of a four-stage roller-crimper. The three independent roller-crimper units are more manageable in transport and are more effective when working over uneven surface conditions than would be a single, rigid unit of 30 feet in width.
Responding to farmer requests for additional design innovations, Kornecki designed a four-stage roller-crimper unit that can be attached to the front end of a tractor. “You can attach a no-till planter on the back of the tractor to save time and fuel in field operations,” he says.
Yet another patented roller-crimper design permits the application of glyphosate during the rolling-crimping process. Applying glyphosate can speed up the termination of plants during wet or cold weather conditions that might otherwise slow down the death of a mechanically interrupted cover crop.
“This concept for herbicide application can be adapted to different roller designs,” Kornecki points out. “In an experiment, I used my patented design of a smooth roller with a crimping bar. While rolling, I applied glyphosate to rye at every fourth crimp using a custom-made boom with a high-speed solenoid valve to momentarily open and close the herbicide flow to a flat-stream discharge nozzle."
With this design, Kornecki applied glyphosate at a rate that effectively terminates rye (87% to 99% kill) one week after rolling “while using only 15% of the herbicide and water typically used in a normal chemical application,” he says. “The cost savings amounted to $17.50 an acre.”
Kornecki has also developed and patented roller-crimpers for the termination of cover crops grown in elevated beds. And then there is a smaller roller-crimper his group has designed that is a PTO-powered machine for walk-behind tractors.
“We have drawings available that farmers can use if they want to build the machines themselves on the farm,” says Kornecki. “Through licensing arrangements, we also try to work with implement companies in order to accomplish a transfer of this technology.
“We are focusing on developing cover crop rolling technology and designing the set of tools that would complement those machines,” he says. “We are hoping to develop the technology farmers need in order to succeed as they work to improve the quality of soil for future generations.”
Ted S. Kornecki