Crimping Cover Crops
(Conservation Currents, Northern Virginia Soil and Water Conservation District, Fall 2008)
No-till farming is agriculture without turning the soil. The advantages of this system are both economic and environmental and include preserving organic matter in the soil, reducing erosion, reducing fertilizer requirements and improving water quality.
Planting cover crops between commercial plantings is an integral part of a no-till system. The goal is to have plant matter covering the soil year round. The cover crop reduces soil erosion by anchoring the soil and reduces weed growth by shading the soil.
Cover crop rolling is an advanced component of a no-till farming system and is used to prepare fields in cover crops for commercial planting. Used for decades in many South American countries, cover crop rolling is a relatively new practice in the United States. The concept is simple; instead of using an herbicide to kill the cover crop, a roller/crimper (think of a 2 ft. high, 15 ft. long, rutted rolling pin) is pushed or pulled over the cover crop by a tractor. The roller crimps each shoot to kill it, but does not cut or mow the shoots as this would cause them to grow back.
The dead plant matter forms a mulch layer that prevents soil erosion and weed growth, and helps the soil retain moisture. As the plants decompose, they replenish soil fertility by providing nutrients to the soil. Because herbicide use is minimized, soil biology is also preserved.
Roller/crimpers can be used on small farms and even in backyard gardens. For example, one small farmer, John Hayden from Jeffersonville, Vermont, built a roller/crimper out of a board, a piece of metal and some twine. The operator simply runs the board over the cover crop, and steps on the board every 8 inches or so to crimp the plant. Hayden uses his home-built crimper in a greenhouse and then plants tomatoes in the mulch. Cover crop rolling appeals to specialty crop producers like Hayden because the rolled cover keeps crops from touching bare soil.
Chris Lawrence, an agronomist with the USDA-NRCS in Richmond, uses a cover crop roller in his home garden. “I have to supplement the rolling with some herbicide, but I still get most of the benefits of cover cropping and have reduced my herbicide use. The concept of cover crop rolling can be applied at any scale.”
The USDA-NRCS, along with several soil and water conservation districts, has been demonstrating roller/crimpers in Virginia. They are trying to determine when and which cover crops to roll in Virginia and are making crimper/rollers available for free to farmers to test. Preliminary results show that cover crop rolling makes sense for some agricultural operations, but not for all depending on the mindset of farmer, the terrain and the type of crops and cover crops grown.
Although the USDA-NRCS does not think cover crop rolling will become widespread in Virginia, according to Lawrence the technology is “an interesting tool and one that opens the door, in particular, for organic no-till production.” A short introduction to the Virginia crimper roller demonstration project is available for download from the USDA-NRCS.
Cover crop rolling can be a beneficial, cost effective and innovative component of no-till agriculture or backyard gardening. The technique is gaining adherents among the agricultural community in the United States because of the soil fertility, economic and environmental benefits it provides. Conservation-minded methods like the roller/crimper help farmers and backyard gardeners alike provide our agricultural resources, while protecting our natural resources for future generations.