Vegetables on a Hundred Acres:
A Visit with Veteran Market Gardeners Martin and Atina Diffley
By Paul Bransky

This article was first printed in the November - December 2002 issue of the Organic Broadcaster, published by the Midwest Organic and Sustainable Education Service.

It was a sunny August day, prime for enjoying fresh sweet corn and watermelon in the shade of a big old oak tree. Twenty-five of us were doing just that, in the midst of Martin and Atina Diffley's 100-acre organic market garden near Farmington, Minnesota. The Diffleys, who have been market gardening since 1973, hosted a MOSES field day to share some of their insights about soil-building, insects, machinery, and growing vegetables.

Organic farming looked especially good that day as we stood under the oak tree, surveying the fertile fields. The runoff from a six inch rain the previous night was flowing like a small river, through a waterway which cut across the farm. But instead of carrying away topsoil, the water ran clear; the Diffleys had planted a wide swath of reed canary grass there when they bought the land ten years ago. "This place used to be farmed end to end," said Martin.

Well-textured soil, also, kept the runoff clear. The Diffleys credit regular legume plow downs for their soil quality, alternating between soybeans in the summer and hairy vetch in fall and spring. "I love the roots of the soybeans; they really seem to loosen the soil," said Martin. Atina praised the crumbly soil produced by hairy vetch for spring transplanting. "The soil is beautiful (after hairy vetch)," she said. "We don't like rye in the spring because it can get out of hand fast, with all that dry carbon. The rye ties up nitrogen while breaking down slowly, and its roots stay in clumps which clog the transplanter."

In the center of their farm the Diffleys maintain giant compost piles, made mainly from manure and wood shavings. In an area where cropland is leased for $150/acre for conventional corn and soybean production, their neighbor squeezes 400 cows onto twenty acres and has a lot of manure to get rid of. "We bring the manure in the fall because of the flies," said Martin. They use bucket loaders to turn the piles, which seemed to work well, judging by the fine condition of the compost on the edge. But Martin was not entirely satisfied; "we may have to buy turners," he said, " because the loaders are not thorough." Martin is also concerned with the National Organic Program composting rules, which currently specify that a windrow composting system must maintain compost between 131 and 170 degrees for fifteen days. (A National Organic Standards Board task force recommended last May that this rule be changed to a minimum of 131 degrees for three days, sufficient to kill pathogens and create nutrient stability. As of now, however, the old rule remains in effect). "I feel USDA standards are really not well-written for this climate," said Martin, "it's a challenge maintaining high temperature in a cold winter". He speculated that to comply with the standards they may have to discontinue making compost, and instead purchase it ready-made.

Marketing, labor, and tomatoes
The Diffleys market primarily to the food co-ops in Minneapolis-St. Paul. "The co-ops are our main business," said Martin. "They're the strongest and most consistent buyers we have. I think the Twin Cities have the largest numbers of coops in the U.S., and they grow 8 to 10% a year."

For many years Martin and Atina also went to the Minneapolis farmer's market, and operated a popular roadside stand at their original farm near Eagan. They established their new farm near Farmington to escape from Eagan's increasing suburban development and road congestion, but continued to sell from the stand until two years ago. "We did a 'quality of life' assessment, and one of our goals from that was to take one day off a week," Martin said. "We cut back our work 1/3 to 1/2 because we don't do the roadside stand. Now we work ten to twelve hours a day." Atina said, " before, I brushed my hair once a week, now I brush once a day."

The Diffleys hire one or two interns to help them with spring planting and plant care, and add three or four people for the harvest season. Eight to twelve dollar per hour factory jobs nearby have forced them to avoid high labor crops. " Our ten dollar to twelve dollar per hour competing wage means we don't grow onions, because of weeding, or potatoes, because of sorting," said Martin. Atina noted that this also improves their quality of life. "I will never sort another potato," she said happily, "you get really tired of it." This year they grew sweet corn, tomatoes, peppers, cucumbers, watermelon, squash, broccoli, cauliflower, cabbage and kale.

Labor costs also shape the way the Diffleys look at the productivity of their farm. They follow a rule of thumb that wages for picking and packing not exceed 15% of a crop's selling price, so they do cost analysis per plant, rather than per acre. Plants producing a lot of "number ones" reduce or eliminate labor costs for sorting.

For example, the Diffleys plant tomatoes in trellised rows ten feet apart, with three foot spacing in the row. "You want lots of air for tomatoes to prevent disease," said Martin. "Give them as much air as you have land for." Atina said that 700 plants trellised 10 ft. apart are producing as much #1 fruit as used to be produced with 3000 sprawling plants.

Besides improved air drainage, this system makes it easier to baby the plants, with concentrated soil amendments, drip irrigation, green thermal plastic, and regular trellis maintenance. They prepare the rows by first applying Calphos, Sustane composted turkey manure, and lots of compost. "We put it on narrow and heavy. Tomatoes are compost eaters," Martin said, though he cautioned to watch that nitrogen levels do not get so high that plants produce leaves instead of fruit. For the trellis they use 6 1/2 foot pieces of 3/8 inch rebar, wrapped with twine in a "basket-weave" pattern along the row.

The Diffleys estimated that thermal plastic consistently ripens their tomatoes two weeks earlier. They have not gotten earlier harvests from transplanting older plants. "Old and young plants tend to ripen fruit the same amount of time from transplanting." Atina said. But larger potted plants tend to yield higher due to a larger root system. Pruning off blossoms at transplant time has also improved yield and quality.

Martin looked over the acre of beautiful tomatoes, and claimed "every one is a number one." We had a hard time finding a bad one to prove him wrong.

Sweet Corn
We saw thirty to forty acres of sweet corn during the farm tour, growing tall and green. "The best corn is in fields where we had vetch," said Martin. "The vetch is generally a eighty pound per acre nitrogen credit, plus we apply four to six tons of compost, which has two to four pounds of N-P-K per ton." In some fields they side dress Sustane (4-6-4) at 300 pounds per acre.

Martin no longer grows "super sweet" varieties, because they die down easily in cold conditions, and some of his customers do not like the sugary taste and tough pericarp. "It'll die in cold soil with less than three leaves, because there's very little starch reserve in the kernel," he said. He also noted that the super sweets' tendency to get sweeter after harvest was not appropriate for his markets, which are all within 45 minutes of the farm. "They work well for a market 2000 miles from your farm where a long sweetness shelf life is crucial."

For early corn varieties, Martin plants at a six inch spacing; late varieties get eight or nine inch spacing. He plants a half-inch deep, with 36" between rows, every ten days. "You have to have accurate planters," he said. "The White series planters are accurate, and the 7000 John Deere is OK."

Late sweet corn crops sometimes get "very wormy," Martin said, depending on the weather. "Ear worms come in on southern winds." At that point, they handle it as a marketing challenge, and a chance to educate their customers. "You can joke about worms," Atina said. "Say you get free bait with your corn, or 'a worm in every ear guaranteed.' If you say nothing the customer tends to get upset about the worms whereas if you bring their attention to them and show them that the worm is just on the tip they generally accept them." Even so, the Diffleys may try next year a new ear worm control in which a mixture of oil and Bacillus thuringensis is hand-applied to the silks (an applicator, called "Zea-Later," is available in the Johnny's seed catalogue).

Cucumbers and squash
We saw about four acres of healthy cucumber vines on the farm. The Diffleys transplant from 72 cell trays into silver plastic, which keeps away cucumber beetles. They plant five times, ten days apart. "We pick from a new planting every twenty days," Atina said. "When cukes become unattractive; people won't buy them."

Squash was a sad story this year for the Diffleys. Just before the field day they gave up a summer-long fight with a huge population of squash bugs, plowing under the vines and planting hairy vetch. It looked like about 15 acres were lost. Atina described a frustrating effort to kill the pests with Pyganic, only to have them return later the same day. "Normally our philosophy is to leave a plant under siege," she said. "This is the first year we used a broad spectrum pesticide." They applied the Pyganic with a 300 gallon high-crop sprayer, but finally it could not reach the bugs adequately once the leaf canopy had closed.

The squash bugs cause plants to wilt and die back from feeding damage. Atina said that the worst infestation was the closest to last year's squash patch, so they plan to grow next year's crop six miles away on rented land. "We did something similar with potatoes," she said, referring to a potato beetle infestation several years ago. "We moved them off-farm, then planted eggplant (as a trap crop) on the old potato field and burned them (with a weed flamer)."

Paul Bransky is a Wisconsin organic vegetable grower, and the former editor of the Organic Broadcaster.