Organic no-till gains momentum in Pennsylvania
Posted: September 1, 2011
The roller-crimper is a large, heavy cylinder, with metal flanges coming off at an angle. Photo by Bill Curran.
The dilemma, as presented by Moyer, primarily revolves around weed management. Organic farmers use a variety of tactics against weeds, but tillage is often a prominent part of the equation. With repeated tillage comes the potential to lose the soil that organic farmers have so carefully built. On the other hand, while conventional no-till allows farmers to minimize erosion and save on fuel, heavy use of some chemical weed-killers can pollute soil and water, and long-term sustainability is threatened by the development of herbicide resistant weeds. What if there were a farming system that combined the best elements of organic and no-till farming, while minimizing the harms? That is the bold question that researchers at the Rodale Institute and Penn State have been asking, along with innovative farmers across the region. The key to bridging organic and no-till practices turns out to be cover crops.
Corn seedlings emerge from a rolled hairy vetch mulch on the left. On the right, soybeans emerge from cereal rye. Photo by Matt Ryan.
Cover crops are certainly not new to organic cropping systems, but using them as a primary weed suppression tool requires a shift in management. Instead of turning the cover crop into the soil before planting, the killed crop is kept on the soil surface and used as a weed-suppressive “mulch” for the following crop. The major innovation that has enabled this approach is an implement called a “roller-crimper”. As the name suggests, the roller-crimper is a large, heavy cylinder, with metal flanges coming off at an angle, that attaches to a tractor. As it rolls, it pushes down the cover crop and “crimps” the stems to kill the crop. The killed cover crop is left in place, and the main crop is planted through the thick mulch that remains. Timing cover crop establishment and termination is critical to get enough biomass to suppress weeds, effectively kill the cover crop in spring, and still get the main crop planted on time. Potential cropping patterns include hairy vetch before corn and cereal rye before soybeans.
So far none of the organic no-till systems being tested are continuous no-till. They are instead “rotational no-till”: tillage is avoided entirely in some phases of the rotation, but is used sparingly in others, often to establish cover crops in fall. Nonetheless, tillage is drastically reduced. For instance, Dr. Matt Ryan, a postdoctoral researcher at Penn State, estimates that tillage operations in a three-year organic grain rotation can be cut from 24 tillage events to just 9 using the roller-crimper system. At Rodale, Moyer is able to mount the roller on the front of the tractor and the planter on the back, planting a field in a single pass. This reduction in tillage would save considerable fuel, not to mention time, relative to traditional organic practices. Given that organic farmers also eschew energy-intensive inputs such as synthetic fertilizers, organic no-till promises to have a small carbon footprint. Other benefits include conserving soil moisture and improving soil quality through the addition and conservation of organic matter.
As with any new management system, organic no-till comes with challenges. At Moyer’s presentation, several audience members were concerned about how to fit the cover crop into rotation, especially in short growing seasons typical of the Northeast. Corn and soybeans often aren’t harvested until October or November, leaving little time to establish a vigorous cover crop. Moyer discussed several strategies to overcome this problem, including choosing short-season varieties of main crops and seeding a cover before the main crop is harvested (e.g. through aerial seeding). Research at Penn State is currently exploring different planting dates and short-season varieties of corn and soybeans in a rotational no-till system, to discover the optimal balance between cover crop and main crop to maximize yield.
Under the new, mulched regime, the pest spectrum tends to shift. Researchers at Penn State have found perennial weeds to be especially troublesome, though incorporating vigorous perennial crops such as alfalfa into the rotation can help. Some early season pests (cutworms, slugs) thrive in the residue-rich environment. Moyer regularly plants above recommended seeding rates to ensure he gets a vigorous stand. One Penn State project is looking at whether later planting dates can avert pest damage to new seedings. While certain pests are exacerbated, Penn State Entomology Professor Mary Barbercheck notes that organic no-till fields host “tremendous populations of beneficial arthropods,” such as ground beetles, spiders, and parasitoid wasps. Most insect pests have not been a problem in their trials.
The roots of no-till are often traced to Edward Faulkner’s 1943 book, Plowman’s Folly. But no-till farmers today might find little resemblance between their own methods and Faulkner’s, which were developed before the advent of no-till seed drills and the widespread use of herbicides. As it happens, cover crops played an important role in Faulkner’s scheme to put the moldboard plow by the wayside, as he advocated for cover crops followed by shallow disking to establish main season crops. Since Faulkner’s time, the organic and no-till communities have diverged. Perhaps cover crops can bring them back together.
For farmers looking to experiment with organic no-till, researchers suggest several tips:
- Start small. Organic no-till is a significant change for many organic farmers and conventional no-tillers alike. Try it out on a small scale to minimize risk.
- Choose wisely. Select cover crops that are moderately priced, easily established, highly productive, and easy to kill.
- Don’t skimp. Get cover crops in the ground on time and at recommended seeding rates. Successful weed suppression requires a dense mat of cover crop residues. If the cover crop looks less-than-ideal in spring, be ready with a plan B.
- Stay sharp. Keep equipment in good shape. To plant through thick residue, planting equipment must be maintained in top condition.
- Plan ahead. Due to the central role of cover crops in this system, planning must start far in advance of a given main-season crop.
- Be creative. Organic no-till will need to be adapted to each farm’s climate, soils, equipment, and resources. But with the principles in hand, many solutions are possible.
Resources to learn more:
Penn State Fact Sheets
- Cover Crop Rollers for Northeastern Grain Production
- Suppressing Weeds Using Cover Crops in Pennsylvania
Penn State Research Projects
- Research Project: “Improving Weed and Insect Management in Organic Reduced-Tillage Cropping Systems”
- Weed Management, Environmental Quality, and Profitability in Organic Feed and Forage Systems
By Maggie Douglas, Graduate Student, Dept. of Entomology
Maggie attended the 2011 PASA Conference with support from the Northeast SARE Pennsylvania State Program.