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Answer: The mechanical roller-crimper equipment used in no-till production, including equipment designs and technical specifications. This roll-down equipment is also known as a "knife roller" and a "crimper/roller."

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 using synthetic herbicides.

There are three notable journal articles dealing with mechanical suppression of cover crops in no-till production that are relevant to this topic because they summarize promising non-chemical methods of killing cover crops for no-till production in organic farming. The paper by Nancy Creamer et al in the 1995 issue of American Journal of Alternative Agriculture (AJAA) highlights the undercutter/roller basket equipment, developed at Ohio State University and North Carolina State University. The paper by Nancy Creamer and Seth Dabney in the 2002 issue of AJAA discusses various mow-down, roller-slicer, and undercutter methods. Finally, the paper by Ashford and Reaves in the 2003 issue of AJAA addresses the use of the mechanical roller-crimper.

Creamer, N., et al. 1995. A method for mechanically killing cover crops to optimize weed suppression. American Journal of Alternative Agriculture. Vol. 10, No. 4. p. 157–162.

Creamer, Nancy G. and Seth M. Dabney. 2002. Killing cover crops mechanically: Review of recent literature and assessment of new research results. American Journal of Alternative Agriculture. Vol. 17, No. 1. p. 32–40.

Ashford, D.L. and D.W. Reeves. 2003. Use of a mechanical roller-crimper as an alternative kill method for cover crops. American Journal of Alternative Agriculture. Vol. 18, No. 1. p. 37–45.

The roller-crimper is a water-filled heavy round drum with protruding blunt metal blades arranged in horizontal, angled, or spiral patterns. These roller-crimpers are most commonly rear-mounted and pulled behind a tractor or draft animals, but they can also be front-mounted on a tractor. When the roller-crimper is pulled 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 silmultaneously prevents re-sprouting and slows down decomposition of the no-till mulch. No-till crops are seeded or transplanted in the same direction as the flattened and crimped cover crop, which slowly senesces and dies out over the course of several weeks, leaving a high-residue no-till mulch.

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 (1–2).

Dana Ashford and Wayne Reeves, researchers with the USDA-ARS National Soil Dynamics Laboratory in Alabama, have thoroughly documented the ability of a roller-crimper to kill a cereal cover crop at the flowering to soft dough stage of growth (3). Several field trials have demonstrated that a mechanical roller-crimper can kill a cover crop just as effectively as herbicides.

On the other hand, 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 mechanical roller-crimper has revolutionized no-till production methods in Latin America where over 40 million hectares (98 million acres) are managed by no-till production systems.

The books and web sites from Carlos Crovetto Lamarca, Rolf Derpsch, and Roland Bunch are critically important resources on the benefits of conservation tillage systems, green manure mulches, and no-till methods on soil health in Latin America (4–6).

In the United States, the roller-crimper method is being promoted by the Rodale Research Institute in Pennsylvania as well as by several university and USDA-ARS research stations.

Jeff Moyer, the farm manager at the Rodale Institute, is spearheading the Rodale research project on knife roller equipment designs and on-farm trials using roll-down, no-till production systems. Moyer explained that machine shop specifications for a build-your-own knife roller are an expected outcome of the Rodale project. These plans will be available when they can convert the Auto-CAD drawn designs to Adobe PDF for posting on the Web site. Some of the Rodale equipment designs are unique by placing the knife 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.

The Web site, hosted by the Rodale Research Institute, has published several noteworthy articles and updates on this project, including very helpful photos of equipment mounted on tractors. Please see the following articles and features from The slide show titled The Long Road to No-Till and the photo gallery titled The Roller/Crimper Gallery are excellent online sources to view equipment designs with close-up photos.

The No-Till + Page

The Roller/Crimper Gallery | May 24, 2005

The Long Road to No-Till Slide Show

New Tools for Organic No-Till—Introducing a Cover Crop Roller Without All the Drawbacks of a Stalk Chopper
By Laura Sayre

Perfecting Organic No-Till Systems Nationwide
By Laura Sayre | September 28, 2004

Farmers Gear up Cover-Killing Rollers for Spring No-Till Planting Season
By Laura Sayre and Greg Bowman | February 16, 2006

Choosing Cover Crops for No-Till Organic Soybeans
By Dave Wilson | October 13, 2005

The Resources, References and Web Resources sections below contain several important documents you may find helpful for further background reading. Several papers and technical notes from agronomists conducting research on the mechanical roller-crimper and its use for suppression of cover crops are listed.

Thus far I am aware of only two equipment manufacturers in the United States that supply bonafide roller-crimpers: Kelley Mfg. Co. in Georgia and and Bigham Brothers Mfg. Co. in Texas (7–8). These roller-crimpers can be custom-made according to any width a farmer might need, based on tractor size and field layout.

In addition, various brands of stalk choppers, roller harrows, cultipackers, bed rollers, and land rollers are being used by farmers, either factory-made or modified, to accomplish the same function of rolling and crimping of cover crops for no-till production.

Farmers who want to “build their own” roller-crimpers can review the slide shows and photo galleries on the Web site and read the accompanying papers from land-grant university and USDA researchers. Farmers who want to duplicate the Rodale Institute’s roller-crimper can obtain a front-mounting 3-point hitch from Buckeye Tractor Co. in Ohio (9).

The paper from NRCS Soil Quality Institute, The Knife Roller (Crimper): An Alternative Kill Method for Cover Crops, and the paper from American Society of Agricultural Engineers, Cover Crop Rollers: A New Component of Conservation Tillage Systems, provide descriptions and design ideas. As noted above, the Rodale Institute will eventually provide Auto-CAD drawings and design specifications for roller-crimpers on the Web page.


1.Wheat Growth Stages and Associated Management (e.g., Feekes scale)
Ohio State University Extension

2. Growth and Development Guide for Spring Wheat (e.g., Zadoks scale)
Universty of Minnesota Extension

3. Ashford, D.L. and D.W. Reeves. 2003. Use of a mechanical roller-crimper as an alternative kill method for cover crops. American Journal of Alternative Agriculture. Vol. 18, No. 1. p. 37–45.

4. Lamarca, Carlos Crovetto. 1996. Stubble Over the Soil: The Vital Role of Plant Residue in Soil Management to Improve Soil Quality. American Society of Agronomy, Madison, WI. 245 p.

Stubble Over the Soil by Carlos Crovetto Lamarca was a landmark book heralding the value and importance of conservation tillage on soil health. Lamarca focuses on soil improvements, soil organic matter, and soil quality that result from plant residues and reduced soil disturbance inherent to conservation tillage systems. His 245-page book is filled with color photos and educational illustrations of no-till agriculture, agricultural implements, cover crops, mulches, crop residues, and soil quality improvements. Larmarca is an agronomist with Chequen farm in Chile, a famous site of no-till agriculture in South America. He has played an instrumental role in no-till agriculture in Venezuela, Columbia, Argentina, Brazil, Uruguay, Bolivia, Mexico, the United Kingdom, and the U.S.

5.No-Tillage—Rolf Derpsch

Rolf Derpsch, No-Till Agronomist

The Knife Roller—A New Development for Permanent Cover Cropping Systems
by Rolf Derpsch

The Importance of Green Manure Cover Crops
by Rolf Derpsch

The Importance of Green Manure Cover Crops and Crop Rotation in the No-tillage System: Experiences from Latin America
by Rolf Derpsch
Paper for South Australian No-Till Farmers Association—SANTFA

Rolf Derpsch is a leading research agronomist based in Paraguay who provides worldwide technical support and education on no-till production systems. The Web sites listed above provide access to his articles, publications, and resources. Also see the following excerpt on knife rollers from a paper by Rolf Derpsch.

Crop Rotations and Green Manure Cover Crops in Latin America
by Rolf Derpsch
Crop Updates 2001: Farming Systems
Department of Agriculture, Western Australia

“GMCC's (green manure/cover crops) and crop rotation are the key factors for the unprecedented growth of no-tillage especially in Brazil and Paraguay. Linked to the spread of cover crops is the use of a 'knife roller' to put the cover crops down to the ground. This implement is not terribly expensive and in many cases can be made locally or by the farmer himself. The implement can be pulled by medium sized tractors or by animal traction and has contributed a lot in reducing herbicide rates in the no-tillage system. The knife roller has become an essential tool for managing GMCC's in many countries of South America. Alternatively steel bars can be welded on top of the discs of disc harrows and the implement used for the same purpose.”

6. Nutrient Quantity or Nutrient Access?: A New Understanding of How to Maintain Soil Fertility in he Tropics
By Roland Bunch, October 2001

Roland Bunch is the author of Two Ears of Corn: A Guide to People-Centered Agricultural Development. He has worked as an agronomist for non-profit organizations in Central American for several decades. The above paper by Bunch highlights the work of the famous Brazilian soil ecologist, Dr. Ana Primavesi, as well as Bunch’s Five Principles of Soil Management for the Humid Tropics: 1. maximize organic matter production; 2. keep the soil covered with green manures and cover crop mulches; 3. zero tillage; 4. maximize biodiversity; and 4. feed crops largely through mulches.

Also see:

An Odyssey of Discovery: Principles of Agriculture for the Humid Tropics
By Roland Bunch
Leisa Magazine, Vol. 11, No. 3 (October 1995). p. 18-19.

Achieving Sustainability in the Use of Green Manures
by Roland Bunch
ILEIA Newsletter, Vol. 13, No. 3. (October 1997). p. 12-13.

Adoption of Green Manure and Cover Crops
By Roland Bunch
LEISA Magazine, Vol. 19, No. 4. ( December 2003). p. 16-18.

Soil Fertility Management Under Pressure
By Roland Bunch
Leisa Magazine, Vol. 13, No. 3 (October 1997). p. 4-5.

7. Kelley Manufacturing Co.
P. O. Box 1467
Tifton, GA 31793
800-444-5449 Toll-Free
229-382-5259 Fax

8. Bigham Brothers, Inc.
[Tech Support: Mike Wisian]
P.O. Box 3338
Lubbock, Texas 79452
800-692-4449 Toll-Free
806/745-1082 Fax

9. Buckeye Tractor Co.
P.O. Box 97, 11313 Slabtown Road
Columbus Grove, Ohio 45830
419-659-2082 Fax


The Knife Roller (Crimper): An Alternative Kill Method for Cover Crops
Soil Quality - Agronomy Technical Note No. 13

This 4-page PDF, an NRCS Technical Note, is of particular interest because it has a technical description of the roller equipment.

“Knife rollers are hollow steel drums, generally 2 to 3 feet in diameter and no wider than 6½ feet, that adjust to soil surface irregularities. More than one can be pulled side-by-side to achieve greater operating width. Approximately 10 blunt knives are along the length of the drum. These knives are 3 to 4 inches tall and are spaced 7 to 8 inches apart (Derpsch et al., 1991; Grooms, 2002). The blunt knives do not cut or chop the stems of the cover crops but crimp or crush them. The drums generally weigh over 800 pounds when empty and can weigh in excess of 1,700 pounds when filled with water. The water is helpful as the height and amount of biomass increase.”

Rolling and Crimping: Scientists Study Alternative Cover Crop Kill Method
Dana Ashford and Wayne Reeves
Online Highlights, Alabama Agricultural Experiment Station of Auburn University
Volume 48, No. 3 (Fall 2001)

Use of a mechanical roller-crimper as an alternative kill method for cover crops. 2003. By D.L. Ashford and D.W. Reeves. American Journal of Alternative Agriculture. Vol. 18, No. 1. p. 37–45.

Modified Abstract: This study was conducted to determine the effectiveness of using a mechanical roller-crimper as an alternative method for killing cover crops. Rye, wheat and black oat were evaluated in terms of ease of kill and optimum time of kill using a roller-crimper, (note: compared to herbicide treatments). Four Feekes' scale growth stages were used to determine optimum time of kill; 8.0 (flag leaf), 10.51 (anthesis), 10.54 (early milk) and 11.2 (soft dough). Plant growth stage was the main determining factor for effectiveness of the roller-crimper for killing the cover crops. At the flag leaf stage, the roller-crimper provided only 19% kill across all covers over the 3 site-years. After plants reached anthesis, the roller-crimper with half-rate herbicide combinations equaled the effectiveness of herbicides alone at their label rate, averaging 94% kill. By the soft dough growth stage, all kill methods were equally effective due to accelerating plant senescence (95% mean kill across kill methods). Use of the roller-crimper alone after anthesis can decrease costs by as much as $26.28 per ha, while providing a kill rate equivalent to that of herbicide treatment alone.

Effectiveness in Terminating Cover Crops Using Different Roller Implements
Ted S. Kornecki, Randy L. Raper, and Andrew J. Price
USDA-ARS, Auburn, Alabama
26th Southern Tillage Conservation Conference

This 10-page PDF is an article from the 26th Southern Tillage Conservation Conference.

“Rollers may provide a valuable alternative to herbicides for terminating cover crops, however, research has shown that excessive vibration that is caused by the roller passing over the cover crop. To avoid excessive vibration, users must limit their operational speed which reduces the number of producers willing to use this technology. To improve the roller’s performance, three different rollers designs were compared: (1) a roller with long blunt ¼ inch steel angle bars equally spaced), (2) a roller with elliptical blunt bars, and (3) a smooth roller with an oscillating crimping bar behind the roller. Preliminary data have shown that the smooth roller with crimping arm produced the highest kill rate of the cover crop (rye, Cecale cereale L.). Data indicate that operating rollers at higher speed (5 MPH) produced significantly higher kill rate of the cover crop compared to low speed (1 MPH). Also, the kill rate evaluated at the end of second week from rolling/crimping was 2 times higher as compared to the kill rate at the end of the first week. The minimum vibration levels measured on tractor’s frame were produced by smooth roller with oscillating crimping arm. This study provides valuable information to further improve mechanical rollers’ effectiveness to terminate cover crops and to give design guidance to researchers who are in the process of developing a mechanical roller widely acceptable to producers in conservation systems.”

Cover Crop Rollers: A New Component of Conservation Tillage Systems
R.L. Raper, P.A. Simionescu, T.S. Kornecki, A.J. Price, D.W. Reeves
ASAE Paper Number: 031020
American Society of Agricultural Engineers (ASAE)
2003 ASAE Annual International Meeting
Las Vegas, Nevada, Held 27- 30 July 2003

This 10-page PDF is a professional paper from American Society of Agricultural Engineers.

Abstract: Rollers may provide a valuable alternative to chemicals for terminating a cover crop. Several producers are now using versions that they have made or have purchased. Most of these producers, however, complain about excessive vibration that is caused by the roller passing over the cover crop. To avoid this excessive vibration, they must limit their operational speed. Experiments were performed to determine if two alternative designs for the blades of the rollers would decrease vibration while maintaining the ability to kill a cover crop. Results showed that a curved blade system or a short-staggered straight blade system significantly reduced vibration as compared to the standard long-straight blade system typically found on rollers. These two alternative blade systems were also found to kill the cover crop as effectively as the long-straight blade system.

Web Resources:

SoilSaver - A Black Oat Winter Cover Crop for the Lower Southeastern Coastal Plain
Conservation Systems Fact Sheet No. 1, National Soil Dynamics Laboratory, Auburn, AL

Roller-Crimper Direction and Various Row-Cleaning Attachments for Cotton Establishment
Research Project Description No. 30, National Soil Dynamics Laboratory, Auburn, AL

Improving Rollers for an Alternative Cover Crop Kill Method
Research Project Description No. 31, National Soil Dynamics Laboratory, Auburn, AL

Evaluation of a Mechanical Roller-Crimper and Reduced Glyphosate Rates on
Cover Crop Desiccation and Weed Dynamics in Corn and Cotton
Research Project Description No. 35, National Soil Dynamics Laboratory, Auburn, AL

Keys to Successful Production of Transplanted Crops in High-Residue, No-Till Farming systems. 1998. By Ronald Morse. p. 79-82. In: Meeting the Challenges — 21st Southern Conservation Tillage Conference for Sustainable Agriculture.

Effects of Rolling/Crimping Rye Direction and Different Row-Cleaning Attachments for Cotton Emergence and Yield
T.S. Kornecki, R.L. Raper, F.J. Arriaga, K.S. Balkcom, and A.J. Price
Proceedings of the 27th Southern Conservation Tillage Systems Conference, Held 27–29 June, 2005, Florence, South Carolina



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