Tillage is often used for pre-plant soil preparation, as a means of managing weeds, and as a method of incorporating fertilisers, crop residue, and soil amendments. Tillage is harmful to soils because it stimulates the breakdown of soil organic matter, sometimes at a very rapid rate. It can also physically damage the soil structure, breaking down soil aggregates and structural elements like infiltration channels.
Tillage often inverts the soil, causing disturbance to soil life. organic notill addresses a criticism often aimed at organic agriculture – that it uses too much tillage and cultivation, which disturb the soil. Vegetable farmers especially may till the soil several times a year as they plant multiple crops and use cultivation to manage annual weeds.
Reduced Tillage is good for soil
Conventional farmers are able to reduce or eliminate tillage in their fields by using herbicides to control weeds and special no-till equipment for planting. As herbicide is not an option in organic productions, many organic farmers rely heavily on tillage to control weeds and are often accused of over tilling the soil. New techniques and tools that have been developed in the last two decades, such as the roller-crimper, allow organic farmers to begin to reduce tillage within production systems.
Organic no-till rests on three fundamental principles: (1) soil biology powers the system, (2) cover crops are a source of fertility and weed management, and (3) tillage is limited and best described as rotational tillage. In goals and ideology, organic no-till is very similar to other kinds of organic farming. These include soil building with organic matter and soil biology; managing weeds, insects, and diseases through diverse and non-chemical means; and achieving general plant health through soil health and good management practices. however, organic no-till uses different methods to achieve those goals.
Much more emphasis is placed on cover cropping, which replaces tillage and cultivation as a means of building soil health and managing weeds.
The Roller-Crimper
The roller-crimper is a specialised tool designed by Rodale Institute that allows a farmer to terminate a living cover crop and convert it into a mulch layer. It works by rolling the cover crop plants in one direction, crushing them, and crimping their stems. When done properly, the plants are killed and left as a dense mat of residue covering the surface of the soil and suppressing weed growth.
Since the system is based on biology and mechanics, it is scale neutral: suitable for use on either small or large farms. The roller-crimper can be pulled behind a tractor, a horse, or even pushed by hand depending on the scale of the operation. It can be mounted on the front or back of a tractor. When mounted on the front, it
frees up the rear of the tractor for a no-till drill or transplanter to plant directly into the rolled cover crop. In this way, the cover crop can be terminated and the cash crop planted in just one pass.
While other tools such as flail mowers and undercutters have the capacity to convert cover crops into mulch, the roller-crimper has some advantages over them. It requires less fuel and creates a more consistent groundcover. While flail mowers and undercutters can result in patchy coverage of the soil, the roller-crimper allows a farmer to create an intact mat that covers the ground thoroughly.
Management considerations for rolled cover crops
The timing of rolling is important in order to achieve 100% termination and prevent the cover crop from re-growing. The correct time to roll for most crops is when the plant is in anthesis, or producing pollen. During this phase of the
plant’s life cycle, it is much more vulnerable and can be effectively killed by the roller-crimper. For hairy vetch, at least 75% of the plants should be in bloom, while 100% bloom is ideal. In eastern Pennsylvania, the proper time for termination of both winter rye and hairy vetch typically falls in late May or early June.
To achieve adequate weed control, there must be enough cover crop biomass by the time the plants reach anthesis. The cover crop should be planted at a high seeding rate and produce approximately 3 to 4 tons per acre of dry matter. For this reason, cover crops that yield a high amount of biomass work best for the no-till system.
In addition, it’s important to select cover crops with a carbon-to-nitrogen ratio higher than 20:1. The higher the ratio, the more carbon and the more slowly the crop will break down. This will provide consistent weed management through the season.
After harvest, the remaining cover crop residues can be disked under and the next round of cover crops can be planted for the following season. Thus, the crop year begins in the fall with planning for the following year. For this reason, organic no-till requires considerable long-term planning.
Source: Rodale Institute
