Research Leads to Profitable, Sustainable Approaches to Onion Production

Onions are one of New York’s most valuable vegetable crops, but growers face a host of challenges: For example, bacterial rot cuts deep into profits, and fragile muck soil, in which most onions are grown, is susceptible to up to one foot of erosion every 10 years.

But the toolbox of solutions is expanding fast, thanks to promising SARE-funded research projects by Cornell University Extension Vegetable Specialist Christine Hoepting, who is using a series of grants to investigate new approaches from conservation tillage to mulches to planting techniques to soil fertility.

In one study, Hoepting got unexpected and positive results: She found that halving plant spacing to four inches could reduce yield lost to bacterial rot by 63 percent beyond growers’ standards and could boost net profit by up to $258 per 100-foot bed for fresh market onions. Using alternatives to black plastic mulch—which absorbs sunlight and can create favorable, warm conditions for bacteria—yielded similarly positive results.

“A lot of growers became aware of how they can manipulate mulches and plant spacing, so they’re experimenting on their own now,” Hoepting says.

One of those growers is Matt Mortellaro, who raises 200 acres of onions for retail distribution on his family’s Elba, N.Y., farm. “We’ve increased densities of our transplanted onions,” he says. “It sometimes results in smaller bulb sizes, which can earn less on the market, but the increased quality more than makes up for it.”

Another unexpected finding helped Hoepting leverage a $10,000 SARE grant into a $220,000 grant from the Northeastern Integrated Pest Management Center: She is now studying the relationship between nutrient levels and bacteria incidence, after noticing that a low-lying area of one test plot suffered disproportionately high damage. She speculated that nitrogen buildup was feeding bacteria.

Mortellaro, like most of New York’s larger-scale onion growers, plants most of his crop in muck soil, which, created long ago from drained wetlands, is rich in organic matter but very friable. Wind damage poses a serious problem under conventional tillage practices, especially during planting season.

“I’ve seen 4-foot drifts of muck. It reminds me of snow,” Hoepting says. “Onions can be decapitated or pulled right out of the ground by strong winds when they’re young.”

While most farmers plant protective windbreaks of barley between onion rows, a window of vulnerability exists in the spring, when both the onions and barley are young. With a SARE grant, Hoepting compared minimum-tillage systems that left the residue of fall-planted oat and wheat cover crops on the ground to a conventional system that plowed the residue under.

Hoepting, who received another SARE grant in 2011 to continue this research, found the residue left from minimum tillage effectively prevented erosion, and improved net profit by 9 percent compared to the conventional system.

“It’s right only for certain acreage,” says Mortellaro, referring to a farm’s most wind-exposed fields. But on the 30 acres where he takes advantage of cover-crop residue, “it’s working to my economic benefit enough that I’m going to continue doing it.”

Want more information? Visit SARE's database of projects and conduct a coordinator-name search for "Hoepting."