Through extensive research, The Rodale Institute has designed simple Manual Crimper-Rollers that can be pushed or pulled by farm tractors (more info). The idea of such a device is that it rolls down cover crops and “crimps” the stem every 5-7 inches to stop the flow of juices through the stalk…thus killing the cover crop while leaving it in place as a mulch. (TIMING is absolutely critical in such an operation…if the crop is rolled down too early, the roots will still have enough energy to sprout new stems, and if it is done too late, there will be viable seeds that will re-seed a new cover crop. The time to crimp/roll is when the plants are in flower, and the first seeds are visible but unripe.)
One thing the Rodale Institute had never done is produce a crimper-roller small enough to be pulled behind a walk-behind tractor, so we decided it was up to us here at Earth Tools. We consulted with the Rodale institute quite a bit, and we actually have some improvements on their design:
In the Rodale designs, they use water to fill the roller to get it heavy enough to give a good crimp to the stems of the cover crop. Instead of water, we used a system of adding weights to the roller via steel standard barbell weight plates. We simply recessed the ends of the roller so that the weights can slip inside the ends of the drum onto the 1” solid steel axle. This means the rig is not made excessively wide, while having the advantages of: A. Very easy (and incremental) weight adjustment; B. No chance of breaking the roller because you forgot to drain the water out in the Winter (Rodale has already busted one of theirs!); C. No chance of welds rusting out and leaking.
We used ¼” thick, 3” tall crimper blades (instead of 3/8” thick, 4” tall), in a Chevron pattern, which means we have plenty of strength, but actually don’t need as much weight per linear foot of roller to get a good crimp. With the space we allow to add weight vs. the blade thickness, we can actually EXCEED the Rodale design on crimp PSI by almost 25% if needed.
The roller has ball bearings with grease fittings. With the 16” ductile-iron pipe (with 1/4” thick wall!) we used, this unit weighs approx. 220 lbs. “un-weighted”. Total diameter with 3” tall blades is 22”. Axle held to frame by 3/8” U-bolts, so loosening 4 nuts makes easy access for weight adjustments. With the target formula of 200 lbs.-per-linear-foot that Rodale designed (based on 3/8” thick blades), we limited the roller width 30 inches, which means when fully loaded with weight, the unit is 500 lbs….we figured this is about the maximum a walk-behind tractor can handle. If your beds are wider, simply make another pass; best done in the same direction as the first (you can always go “back” across the field on a different bed, so you don’t waste a trip)TO GET A GOOD CRIMP, THIS UNIT MUST WEIGH A MINIMUM OF 400 LBS., WHICH MEANS ADDING 180 LBS. (OR MORE) OF WEIGHT. One of the first customers we had to purchase one of these units told us that it “didn’t really work…the cover crop wasn’t killed”…and when we questioned him as to how much weight he had added, he said “A 25 lb. weight on each side”….Well, he is correct…with that little bit of weight on it, it WON’T crimp the cover crop effectively at all! Frankly, you are better off adding more weight than you may need (say, 250 lbs total), and only REMOVING it if the stems are actually getting cut as they are crimped. So pile the weight on, run over a few feet of crop…and inspect it. Crimps should be nice and deep, all through the “mat” of rolled-down material, but NOT cut. Keep in mind that more fibrous crops with tougher stalks (like annual rye) require more weight than softer stalks (field peas, vetch), and how dense that particular stand of crop is planted will make a difference too…so make notes! This is a cutting-edge technique, so you are the “in-the-field” (literally) researchers!
Crimp-Rolling a cover crop does NOT work for all types of vegetable crops to be planted into (for example, Lettuces, Greens, Carrots, Radishes, etc. cannot deal with the coarse “mulch” residue, and need a “cleaner” seedbed…such as you would get by flail-mowing the cover crop and working it into the soil), but for crops that it will work with, this tool offers an extremely simple and totally reliable design, and the crimp-rolled method offers the least possible soil disturbance (and therefore most intact soil structure).
The Rodale Institute has been experimenting with designs for transplanters (for vegetable starts) and seed drills to plant through the cover crop mulch/residue. As far as we can determine, these tools may be cost-effective for the scale of agriculture done with full-size tractors (large acreage fields), but they are NOT cost- or time-effective for the scale of agriculture performed by walk-behind equipment. Therefore, planting through the residue is best done manually. The weed suppression and moisture retention the mulch provides (not to mention the addition of organic matter to the soil as it decomposes) more than offset the labor of planting through the residue.
FITS: All BCS & Grillo Walk-Behind Tractors with Differential drive. Tractor may require wheel weights for added traction.