ADAIR, Iowa (AP) — Weeds might be the toughest challenge Dustin Farnsworth faces, shifting from growing conventional corn and soybeans to organic row crops.

The Adair farmer battled buttonweed and other unwelcome intruders in his soybeans the first year he moved away from synthetic chemicals.

He's also fielded some unwanted comments.

"My neighbors said, 'Farnsworth, it's a weedy mess. It looks like hell," he told The Des Moines Register .

The criticism will be worthwhile, though, when the beginning farmer can get double or triple conventional prices for his crops.

Although still a small piece of Iowa farming, more and more growers are shifting to organic corn, soybeans and other crops to improve their bottom line.

The number of Iowa farms and acres certified as organic have each climbed about 5 percent last year over 2015, U.S. Department of Agriculture surveys show.

Iowa had 732 organic farms with 103,136 acres in 2016. Sales climbed 9 percent to $131.2 million.

The state ranks fifth nationally for its number of organic farms, although it's less than 1 percent of Iowa's 88,000 farms.

California leads the nation with 2,713 organic farms, pulling in nearly $2.9 billion.

Total U.S. sales for organic grain, meat, eggs, milk, fruits and vegetables reached nearly $7.6 billion last year, the USDA data show.

Altogether, the organics industry is closing in on $50 billion annually.

Kathleen Delate, an Iowa State University horticulture professor, said farmers are attracted to organic crops for many reasons, but a leading one is financial.

"Organic corn is $8.70 and organic soybeans are $19," she said. "That's definitely an enticement in an era of low commodity prices."

Conventional corn is selling around $3 a bushel in Iowa, and soybeans are about $9. Both are below the cost to produce the crops, based on statewide averages.

Many Iowa farmers face a fourth year of possible losses.

Looking at recent prices, farmers converting their whole operation to organic over five years would average $206 per acre, said Craig Chase, an ISU Extension local foods specialist.

Conventional farmers would have lost an average of $33 an acre over that time, based on Chase's models.

Even though organic yields are lower, prices are higher and production costs are slimmer.

"If conventional prices stay where they are at, it will be difficult to show any profit if the farmer is paying him or herself" for equipment, land and labor costs, Chase said.

"The organic system, if well-managed, could show a significantly higher profit per acre," he said. "The key to organic profitability is the ability to manage the various risks."

The premium that comes with organic corn and soybeans is the primary reason Farnsworth decided to transition a third of his farm to organic.

"I consider myself a small farmer," Farnsworth said. "Without going out and trying to take land from neighbors, which never pays very well, the best thing to stay fully employed as a farmer is to go organic."

It also fits his personal interest in using fewer chemicals, and relying less on genetics for a good crop.

He shifted to crops that were not genetically modified before moving to organic. "I like the self-reliance that organic system gives me," said Farnsworth, who farms with his wife, Jennifer.

Transitioning from conventional crops to organic takes three years, although the third year can net an organic crop, depending on the last application of prohibited synthetic chemicals.

Some natural substances can be used as herbicides, insecticides and fungicides in organic farming, Delate said. "It's a misnomer to say we don't use any pesticides," she said.

"If it's found in nature, it probably can be used in organic farming ... as long as it doesn't cause harm to people and animals," she said.

Growers often move to organic crops because of health concerns for themselves or others, Delate said. Many want to get away from synthetic chemicals.

"Once farmers transition, they see the environmental benefits, too," she said.

Even though organic farmers use more tillage to control weeds, which can cause erosion and deplete fertility, Delate said organic farming practices that include using cover crops, manure, compost and a broader crop rotation builds organic matter, based on ISU's research.

The trick — sometimes an art, Delate said — is to catch weeds before they can overwhelm a field and a farmer.

"Timeliness is critical" between the weather and fast-growing weeds, she said. "Sometimes you only have a four-hour window to rotary hoe," or till a field.

"You have to always be watching. ... If you see weeds, it's already too late," said Farnsworth, who added he's "learning volumes about what's the wrong thing to do."

Delate said it's hard for farmers to live with weeds in their fields —"a single weed can signal that you're a bad farmer."

Over time, organic farmers get more adept at weed control. In fact, Delate said some experienced organic farmers' fields are as clean as neighboring conventional crops.

George Naylor, who has grown conventional crops for about 40 years, is bringing his first organic soybeans off about 80 acres.

Given the weeds, he's happy with the yields.

"The risks you're taking are much greater," said Naylor, who farms with his wife, Patti. "Figuring out how to deal with that can be stressful."

The Churdan farmer hasn't sold his organic soybeans yet. He could get up to $20 a bushel, if the crop qualifies for food production.

"I'll believe it when I see it — after they cut a check," he said.

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Information from: The Des Moines Register, http://www.desmoinesregister.com