Forage intercropping for resilience

by Tamara Scully
A presentation by Cornell professor Matt Ryan, and PhD student Ann Bybee-Finley, of the Sustainable Cropping Systems Laboratory, discussing an ongoing three-year forage resiliency experiment, was held recently in conjunction with a pasture walk at Larry and Denise Moore’s 270-acre certified-organic dairy farm in Lansing, NY. The “Forage Intercropping for Resilience Experiment,” which includes trials at the Musgrave Research Farm in Aurora, NY along with experiments being held at the University of Vermont and the University of New Hampshire, is known by the acronym FIRE, and is being managed organically.
“The more I understood that climate change was having a large effect on the types of cropping systems and viability of farms, particularly in the organic sector, which has the pasture rule,” the more it became clear that managing risk in forage systems was imperative, Bybee-Finley said.
Researchers from all three institutions are seeking to determine what types of crop diversity could lead to increased forage yields, and withstand the vagrancies of climate change and the weather variability with which Northeastern region farmers will face. The research experiment was designed to answer “How much is crop diversity helping, and what kind of diversity matters?” she said.
Experimental design
The best way to manage risk is for a system to recover quickly from disturbances, including drought stress, excessive rain, pest pressures and market volatility. A diverse cropping system is one which can absorb these disturbances by spreading out the risk, and can adapt to adversity through flexibility in management.
Annual forage cropping systems hold the potential to fill in the gaps in forage availability when the inevitable “summer slump” in cool season perennial pastures occurs in the Northeast. Planting pastures with a diversity of genetics, rather than in a monoculture, increases resiliency and lessens risk.
FIRE was designed to compare the yield from an alfalfa-based perennial pasture systems with that of a double-cropped annual system. Both systems were managed at four levels of intensity: very low, low, high and very high. At the very low level, one species and one variety of seed were planted. At the very high level, four species of forages, with four varieties of each species, were planted together. The low system represented one forage species, with four varieties of that species planted together in an intracropped system, while the high intensity system included four species of forages, with one variety of each species, in an intercropped system.
Researchers collected data on crop performance, via biomass measurements at the species level using quadrats, as well as by plot-level yields collected after harvest. Identifying weeds and quantifying their abundance; measuring soil health indicators; performing partial budget analyses, and ultimately incorporating milk production estimates based on forage yield and quality are all important means of assessing differences across cropping systems.
Sowing the seeds
“We tried to choose cultivars that were all very different from each other to insure as much genetic diversity as possible,” Bybee-Finley explained.
Researchers treated each plot as if it were to become harvested forage, and therefore matching the maturity of each species and cultivar used in any given plot was a priority. Management decisions, such as planting mixtures with similar growth rates to avoid suppression, or seeding aggressive species in a mix at lower rates so they don’t out-compete the others, are important and complex when handling diversity in cropping systems.
Because trials were conducted in three separate locations, with very different weather patterns seen, researchers ultimately will have a better understanding of the impacts of crop diversity — whether within a single species via the use of different cultivars, or in fields planted to multiple species — as a risk management tool.
“Where they have different weather, and different circumstances, it (research data) can potentially look very different,” Bybee-Finley said. They were careful to select forages that would be expected to thrive in all three test locations. “If you plant it, it should have a reasonable chance for survival.”
Alfalfa was chosen as the lead species in the perennial forage mixtures because it is a favored forage on the region’s dairies. The very high diversity alfalfa mix included four varieties of alfalfa — Viking 37HD, FSG 420LH, KF Secure and Roadrunner — along with four cultivars of orchardgrass, four of timothy, and four of white clover. The high diversity plots included one cultivar of each species, while the low diversity plot was seeded with all four alfalfa cultivars and the very low plot sown exclusively with alfalfa Viking 37HD.
For the summer annual forages, the Hayking cultivar of sudangrass was planted alone in the low diversity mix, and joined by three other cultivars — Piper, SSG886 and Promax — in the low diversity mix. The high and very high treatments included pearl millet, sorghum-sudangrass and ryegrass, either one or four cultivars of each respectively.
Trials of winter annuals saw triticale 815 alone, or planted in conjunction with red clover, cereal rye, winter pea and other triticale varieties.
Seeds were mixed together and run through a no-till drill. The annual plots were fertilized, plowed, disked and harrowed, planted, and then harvested in mid-June. After harvest, the process was repeated with winter annuals sown in late September, in a double cropping system. The perennial fields were no-till seeded in August, replanted in May, and first cut in early June. After fertilization, a second late July cut was harvested.
New York preliminary results
Conditions in 2017 at the New York site included a mild winter, wet spring, and a leaf hopper issue. The annual system yielded more dry matter per acre than the perennial system overall. Across both systems, the high and very high diversity plots had higher yields. Winter annuals had a higher digestibility than summer annuals or perennials. Summer annuals had lower crude protein that winter annuals or perennial forages. Soil samples have not yet been assessed to compare soil health indicators across treatments.
The leaf hopper concerns demonstrated the importance of having some forages which were resistant to the pest.
“There’s something to it with these variety mixtures. That’s what we’re trying to do here with the diversity,” Ryan said.
We’re trying to “dissect this idea of intercropping,” with these mixtures, to see what works in what conditions. “Having a backup plan is really what this adaptive management is all about.”
Another part of the research study is to conduct dairy farmer interviews to better understand management decisions and risk management mitigation concerns. Interested farmers can contact Ann Bybee-Finley at kab436@cornell.edu. More information on the experiment can be found at: blogs.cornell.edu/scslab/fire
A report on the initial results from the Vermont trials can be found at www.uvm.edu

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