It’s the great (oilseed) pumpkin! Research into organic production shows potential for this new crop

by David Lindsay, Jan./Feb. ’09 issue of Rural Delivery magazine

Many gardeners like to see a few pumpkins wallowing in the autumn sunshine among the more upstanding vegetables. We may even turn a blind eye to the delinquent vines, which strangle neighboring crops then attempt to escape justice by hightailing it across the lawn.

But as an agricultural product the pumpkin does not get a lot of respect in North America. It is relegated to a seasonal niche, either as a pie filling or as a Halloween ornament, and the really obscene specimens are hauled off to some county fair freak show.

In parts of Europe, however, the pumpkin is held in higher esteem – not for its appearance, or for its pulp, but for the oil pressed from its seeds. Especially in Austria and Slovenia, this dark green oil, with its distinct nutty taste, has long been favored for salad dressing. And recent scientific findings about the healthful properties of pumpkinseed oil, notably as a source of essential fatty acids, have increased demand around the world. Suddenly, pumpkin seeds are being used as an ingredient in granola and snack bars, and processed into nutritional supplements.

That’s why Joanna MacKenzie has been examining how oilseed pumpkins could be grown on a commercial scale in the Maritimes. As a research associate with the Organic Agriculture Centre of Canada, at the Nova Scotia Agricultural College in Truro, N.S., MacKenzie is analyzing data from two years of field trials comparing different cultivation practices and different varieties of naked-seeded (i.e., lacking the coarse white hull) or Styrian pumpkin (named for the state of Styria in southeastern Austria).

The trials were designed to evaluate organic methods of insect control, weeding, and fertility management. Oil yield and quality were assessed when the pumpkin seeds were processed.

“I think there’s promise there,” MacKenzie says, though there are also some challenges that may make farmers reluctant to become early adopters of this new crop.

METHODS

Competition control is not one of those challenges. It’s a common-sense combination of hand weeding between rows, and use of a tractor-mounted cultivator early in the growing season. Once pumpkins are well established, weeds don’t stand a chance.

As for controlling insects, an organically-approved kaolin clay product sold under the trade name Surround, applied with a backpack sprayer, proved slightly more effective than a canola oil spray. As is the case with many organic methods, some vigilance is required. Repeat applications may be necessary following rainfall.

“It’s really important to deal with the Cucumber beetles,” MacKenzie points out. “It’s not just the damage to the leaves; they can also transmit bacterial wilt, which can wipe out your crop.”

The trials also compared plots fertilized at various rates with pelletized poultry manure, versus plots where Red clover and Timothy had been incorporated as a green manure before the pumpkins were planted. MacKenzie says she was much encouraged to find that the latter approach was relatively effective.

“Clover plow-down did really, really well. You’re greatly minimizing your external inputs, and a lot of people are planting a cover crop anyways, so you’d really be getting a benefit from that.”

Of course, green manuring depends on good timing, and getting the timing right depends on the weather. If planting is delayed, the pumpkins may not grow to maturity, and seeds that are not fully mature will not provide a good oil yield.

Because maturity proved to be a problem in 2007, earlier plantings were done in the 2008 trials, but cool, wet weather resulted in poor establishment and some mildewing.
“The ground was still too cold at the end of May,” MacKenzie says. “Pumpkins like really warm soil conditions – at least 15 degrees Celsius, and preferably about 20 degrees.”

A better solution to the maturity problem was to try shorter-season oilseed pumpkin varieties as well as the seed imported from Austria in 2007. Mackenzie says the 110-day Kakai variety from Johnny’s Selected Seeds – producing greenish pumpkins with orange stripes, similar to the Austrian type – performed well. Also promising is the 100-day Snackjack hybrid from Veseys Seeds, which produces softball-sized orange pumpkins.

“The oil contents were right on target this year, so they must have been mature.”
MacKenzie says that target is 45 to 50 percent, based on dry seed weight. It sounds like a lot of oil, until you consider the fact that a fresh pumpkin – even one of these oilseed varieties – will yield only 1.5 to 3 percent of its weight in dry seeds. Herein lies a significant technical challenge for prospective growers.

Pumpkins are bulky, so harvesting them is a major undertaking. The research plots were scaled back in 2008 for this reason.

EQUIPMENT

Andrew Kernohan, of Ballymena Farm in Parrsboro, N.S., took part in the 2007 trials, growing about an acre of the Austrian variety. “It was about 2300 pumpkins, as near as I could count,” he says. “It’s very labor-intensive, or else the equipment to harvest them is very expensive.”

Kernohan says he would be willing to try oilseed pumpkins again if this issue could be resolved. “It would be a wonderful thing if we could do it. The taste is wonderful. It would be a nice little niche industry. It would be a high-value crop, and it would be an alternative to growing grain.”

Drew Jeffrey, an organic farmer in Mount Mellick, P.E.I., just outside Charlottetown, has also experimented with oilseed pumpkins, growing about four acres in 2007 and three acres in 2008. He too has found harvesting costs are a barrier to profitability. “We had about 10 guys out in the field,” he recalls.

In February of 2008 Jeffrey visited a manufacturing plant in Austria that designs and builds equipment for harvesting oilseed pumpkins. The typical set-up is a roller mounted on the front of a tractor to push the pumpkins into windrows, followed by a machine to pick them up and crush them, collecting the seeds in a tank and expelling the pulp. (Pumpkin flesh could be fed to poultry or hogs, but in Austria it is generally left on the field. Jeffrey says it is not palatable to cattle, though it could be incorporated in a total mixed ration.)

“What we were seriously looking at doing was planting 100 or 120 acres, and bringing the equipment over,” he says, “but to do it would probably be $200,000 or $250,000.”

For the time being, producing organic soybeans is more lucrative for Jeffrey, but he’s still interested in oilseed pumpkins. “The price now is $5000 per dried tonne. There’s a huge market for these seeds, and the market pretty much finds you. You don’t have to go looking for it.”

He says if there were some government support to help with mechanization, oilseed pumpkins could become a viable agricultural product in this region. “They can be grown here, but you couldn’t make any money doing it by hand.”

Companion piece: Oil baron

OACC gratefully acknowledges the author and Rural Delivery for permission to post this article.

Posted May 2009