Essentially, the roller/crimper is a drum or a cylinder with curved blades, which when operating, lays the cover crop over in one direction and crimps or crushes its stems. The combination of these two actions kills the cover and turns it into a thick, weed suppressing mulch in a single pass. You won’t need herbicides to provide 90 to 100 percent knockdown. Farmers can use the roller/crimper as part of an organic operation, or as part of a conventional one to reduce the use of herbicides and improve the bottom line.
As with any field operation on any farm, you need the right piece of equipment to accomplish the task effectively and efficiently. This is especially true in a cover crop system where every operation has an impact on the success of crop yield and quality. These ramifications are particularly evident in organic systems where every part of the system is closely interconnected to every other part. Organic farming needs to be considered as a holistic system.
Adopting organic no-till methods creates a dynamic change to this holistic system. It’s hard to make one change without affecting the whole farm management plan. As we discuss organic no-till, we need to be especially mindful of how it will impact every other part of the system. The impacts can be seen from an agronomic perspective through changes in weed species and location, from a soil’s perspective as you’ll see changes in a soil’s ability to retain water and support greater microbial diversity.
Typically, organic farmers plow too much. In some vegetable operations, growers will use primary tillage as often as three times a year, secondary tillage, plus the cultivation for weed management. It seems natural to try to eliminate tillage from an organic system, which attempts to improve the natural resources it utilizes. At Rodale Institute, we recognize that tillage can be destructive to soil macro and micro flora and fauna and can lead to soil erosion.
So, we began our journey following the path laid out by conventional farming systems. We began by reducing tillage through the practices known as conservation tillage. Our earliest work was centered on employing conservation tillage practices in order to get away from using a moldboard plow. We began to use a chisel plow that left a good percentage crop residue on the surface of the field, did not invert soil layers and minimally disturbed the soil while improving drainage.
However, the chisel plow created problems that were not noticeable in the first few years. Over time, we began to observe an increase in weed pressure from annual weeds. Here is what happened. With inversion tillage (moldboard plow) we were able to bury small weeds and create a good seedbed. The chisel plow, which works with a “stirring” action, did not kill all of the small weeds. Many of these weeds then had a “head start” on our cash crops. As more and more of these weeds escaped the cultivation practices, our weed pressure increased. Our experience at Rodale points to an essential dilemma. Conservation tillage (including no-till) developed out of a chemically-based weed suppression program. Reducing tillage grew up hand-in-glove with the herbicide industry. In other words, as a conventional farmer reduces tillage he or she also adjusts the chemical herbicides to make up for the changes in tillage. This is chemical weed management at its best. Needless to say, this type of management has no place in an organic system. We learned that you couldn’t get something for nothing. In order for an organic system to succeed, you need to adjust and change other parts of the system. Consequently, our system was doomed to fail in a very short time. We were reducing tillage bout not increasing anything except our potential for weed pressure to build.
We have known for decades, from work in the Rodale gardens, that we could use mulch to smother annual weed and prevent them from germinating and growing. The challenge was how to mulch large acreage in a cost effective and time efficient manner. We knew we could never afford to simply adopt garden mulching techniques into farm-scale production, especially for lower value grain crops.
We are continuing to explore ways to solve the problems, which may arise from time to time in an organic no-till system –as happens in any other farming system too. While the organic no-till system is very exciting and holds great promise for farms to aid in reducing the need for cultivation and tillage, there may be times when the weed pressure is too great or perennial weeds get a toehold and begin to express themselves in a no-till crop when they break through the mulch supplied by the cover crop. If this situation occurs, farmers and crop managers have the opportunity to intervene with additional field operations. In this particular case, standard cultivation of the crop is almost impossible due to the tremendous amount of cover crop residue remaining on the field (our weed suppressing mat). Not to fear, new technology is available to remedy this situation.
The primary goals and objectives of a true no-till system haven’t changed and I haven’t abandoned the idea of eliminating cultivation from the production of no-tilled row crops. However, with minimal activity, research is indicating we have the ability to rescue a crop from weed infestation that threatens to reduce yields to overtake our no-tilled crop.
Gradually, we realized that we needed specialized equipment to roll and crimp the cover crop. The tool needed to have three characteristics: a) it should be front mounted to improve the contract between the tool and the ground, b) it should roll the cover crop in one direction and c) it should crimp but not cut the plant material. We finally identified the design criteria we were looking for. Now we had all the pieces in place. We had cover crops that could perform the functions we required, we had a specialized tool and roll and crimp the cover crop, and we had planting equipment that could get the seed in the ground. There were many questions still to be answered: when do you roll, what species and variety of cover crop should be planted, how do you tool-up and adjust the planter, are there insect dynamics that need to be addressed.
The no-till work continues-
The design and development of the roller/crimper at Rodale began with an examination and analysis of many of their tools including rolling stalk choppers, rolling harrows, and even flail mowers. These tools were already in use at our farm. Although they were designed for other functions, they appeared to adapt well to managing cover crops. However, none of these tools were designed specifically to roll cover crops and each had drawbacks. So we sought to develop a specialized tool for the job of rolling and crimping cover crops, instead of using a modified implement intended for another purpose.
Let’s start with the example of the rolling stalk chopper. The rolling stalk chopper consist of eight rolling drums (in 4 row unit) arranged in two parallel rows. The implement is rear mounted on a tractor. As with any farm tool, some things about the rolling stalk chopper worked well, and some things didn’t. The rolling stalk chopper has two big drawbacks. First, the machine is rear mounted on the tractor, which leads t some problems in completely killing the cover crop. As the tractor tires pass over the cover crop, they knock down the cover crop and make the indentation in the ground. This is especially true if the soil is wet. This means that the implement can’t do its job effectively – the cover does not receive the full impact of the rolling stalk chopper. The stems of the cover crop remain uncut and often have a tendency to stand back up. This defeats the purpose of the operation and eliminates the mulching effect of the cover cop. Also, since the rolling stalk chopper is rear mounted, the planting must be done in a separate pass. This two-pass operation increases the time and energy invested in establishing the cash crop. With the thick mat of rolled cover crop covering the ground, it can be difficult to see where the planter has already been. Traditional row markers can’t make a good line in the thick residue and foam markers would be a necessary option.
Another issue with rolling stalk choppers or mowers, as well as some other tools that have been used for organic no-till, is their tendency to cut the cover crop into small pieces. The cutting creates several problems. First, the cover crop breaks down faster and is less effective for weed control. Second, when the cover crop is cut, it is no longer anchored in place by its roots. Consequently, it ends up in all kinds of places it shouldn’t. For example, it can get dragged by the planter and clog the machinery. In addition to the problems with the machinery, it creates bare patches that can become weedy later on in the season. The mulch is not distributed evenly across the field, with some thick areas and some thinner ones. There are several other key design points that we considered important when reviewing existing equipment and the creation of our own roller/crimper. One of those was the number of moving parts – in other words, the number of points where the cover crop could get tangled in the machinery as the rolling operation takes place. By creating a roller with only two bearings we were able to minimize both wear points as well as reducing the areas where wrapping of the cover crop might take place. We also wanted to design the blades in a way that would prevent them from ripping or pulling at the cover crop. This pulling action would create bare patches in the cover thereby providing an opportunity for annual weeds to germinate. This was accomplished by mounting the blades ono the cylinder at the angle of 7 to 10 degrees off of the perpendicular.