COLUMBUS, Ohio - Organic farming sounds simple - no chemical fertilizers, pesticides, herbicides or genetically engineered plants. But succeeding at it can be complicated.

A recent wave of research at universities across the country seeks to take some of the guesswork and financial uncertainty out of the practice.

"There's so many things that interact naturally that you can't control that you could with chemicals. I think you could spend a whole lifetime learning how," said Dale Dyko, who grows organic corn, spelt - a type of wheat - and soybeans on about 30 acres in Xenia in western Ohio.

Organic food sales almost tripled from 1997 through 2003 to $10.4 billion, according to the Organic Trade Association. Organic fruits and vegetables account for most of the sales, while organic meats and snack foods, such as corn chips and rice cakes, are two of the fastest growing segments.

"Organic agriculture is just a growth culture within all agricultural industries," said Matt Kleinhenz, the lead researcher on a study at Ohio State University. "Scientifically and practically we don't know enough about it."

The U.S. Department of Agriculture says it has been increasing its financial support of organic farming research at universities and other organizations since 2000. Funding for one program has increased nearly fourfold to about $1.9 million from 2000, said Philip Schwab, a policy adviser with the agency.

Organic farming, though, makes up only a small part of U.S. agriculture. Certified organic crops were grown on 562,486 acres in 2002, a fraction of the 300 million acres on which all crops were harvested, according to the USDA's census.

Making money at farming has for generations meant using chemicals to kill weeds, fight off insects and disease and otherwise wrench predictable results from soil and plants. Going organic - abandoning use of nearly all chemicals - unleashes a different set of variables.

"Conventional ag is a little bit more like a recipe. You know what to pour out of the bag," said Nancy Creamer, director of the Center for Environmental Farming Systems at North Carolina State University.

Farmers like Ed Snavely, who switched from traditional to organic methods in 1986, say they have relied on advice from other growers and trial and error to develop their techniques.

Snavely monitors temperature and soil moisture on his 100 acres in Knox County and scrapes his fingers through the dirt looking for young weeds just below the surface that look like tiny, white hairs. Waiting even a day too long can allow the weeds to grow too big to manage easily, he said.

Typically, Snavely weeds three times before planting his crops, which include buckwheat, soybeans and hay, and four times after planting.

"With most of your conventional farmers, it's plant, spray and forget. If you're going to go organic, you can't plant and forget. You've got to be out there walking your fields," he said.

Going organic can also be a financial risk. In subtracting nearly all chemicals, farmers say they also subtract from their profits in the first few years. It takes time to master a new way of farming.

Compounding the problem, a farmer who switches from conventional growing methods has to wait three years to obtain certification from the government, a label that helps ensure higher prices.

Snavely said he would have benefited if more scientific data had been available when he made the switch.

"I took some big yield reductions because I didn't know what I was doing," he said.