Grower strengthens soil, saves berries

John Schmitz/Capital Press Biological/organic farmer Bob Wilt churns up a batch of compost for his blueberries south of Corvallis, Ore.

Composting, trusting 'Mother Nature' revitalizes operation


For the Capital Press

Talk to blueberry grower Bob Wilt, owner-operator of Wilt Farms in Corvallis, Ore., and he'll tell you that the key to producing great fruit is building robust soils.

While his 75-acre farm is certified organic, Wilt likes to refer to himself more as an "aerobic biological" farmer who's more concerned about establishing hearty soil organisms and improving tilth.

"There are a lot of concepts that are both biological and organic, and I tend to focus real hard on the biological. If anything, I'm following organic rules better than a lot of (certified organic) people do."

Wilt, who is self-taught, said he adopted his current approach to growing blueberries after seeing his conventionally grown crop falter. "(It) started growing backwards. Less crop, less health, more insects, more disease."

The reason for this became obvious when he had his soil analyzed and found that "basically, the lights were on but no one was home, biologically speaking. So we started going down the path of biological farming. That meant cutting back on fertilizers and pesticides."

Over the past six years, Wilt has been nourishing his soils with compost made from various feedstocks, including used horse, cow and sheep bedding from nearby farms, as well as grass seed straw.

"It's a lot of work. You handle a lot of volume. You use what's close by. Freight will kill you."

Wilt, who is certified by Organic Certifiers out of Ventura, Calif., said he looks on composting as "the cornerstone of our nutrition for our berry plants." He also regards the fertilizers he cooks up as another one of his crops.

He said that at first, composting was more expensive than conventional inputs due to start-up costs, but that eventually it will cost about the same.

Switching from conventional to biological/organic was no picnic, either.

"There's a reason they call it 'transition,'" Wilt said. "It doesn't come easy. You've got to have a different mind set."

At first, he wasn't all that concerned about evolving into an organic operation, but he told himself, "If we're going to go down this road, if we just keep records we'd be organic and get paid (a premium for his crop)."

While blueberries flourish in lower-pH soils, Wilt said, he's not all that concerned about reaching the optimum pH with composting.

"Where we're biological, the biology more or less takes care of the pH. It's one of my lesser concerns. Mother Nature has a way of making things happen, and, quite honestly, if we get out of her way, she'll do a better job than we do."

So far, Wilt's approach to growing blueberries has proved successful, especially if you look at some of the nutrient levels in his blueberries.

For example, tests done by an independent lab have shown that Vitamin A and E densities are much higher in his berries than in berries grown conventionally or even organically.

Wilt grows mainly mainstay blueberry varieties such as the omnipresent Bluecrop, but has been converting some of his acreage to new cultivars developed at Michigan State University, such as Draper and Liberty. He likes Draper because it's a fresh-market variety that is firm and sweet. Draper also ripens more evenly, with no purple berries come harvest.

Wilt wholesales and direct-markets his berries and value-added products under the Sunset Valley Organics label.


Composting not for the impatient

On Wilt Farms, Bob Wilt makes use of several waste streams for preparation of his compost, including used livestock bedding, grass seed straw, sawdust and seed screenings.

These materials are mixed together and laid out in windrows, where they are turned an average of once a week.

Wilt uses a ride-on compost turner for the job.

During the ripening process, the mixture is adjusted should temperatures become too low or too high. Sometimes he must add moisture.

Composting takes time, Wilt said. Once the compost's temperature has dropped below 110 degrees F, he moves the windrowed compost into a large pile, where it cures for at least one year before being applied.

The finished compost is usually applied at a depth of around three-eighths inch with a sawdust spreader.

Wilt is working on his own over-the-row compost spreader.

In addition to encouraging the growth of soil microbes and improving soil tilth, composting for Wilt has reduced soil compaction, making it more suitable for the growth of roots.

For those interested in learning more about composting, Oregon State University's North Willamette Research and Extension Center in Aurora is planning on presenting a workshop during the spring of 2010.

-- John Schmitz


OSU Extension agent Nick Andrews:

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