Eager to tap into that demand, Target, one of Walmart’s primary competitors, said on Tuesday that it would expand the presence of organic products in its stores. At Walmart, internal company research found that 91 percent of customers said they would buy “affordable” organic products if they were available, executives said.

Image Walmart will introduce Wild Oats products in 2,000 stores in the coming months.

While organically produced grains do not necessarily cost more to grow than other types, Lynn Clarkson, founder of the Clarkson Grain, which processes and sells organic and conventional wheat, soy, corn and other grains, said they commanded a huge premium because they were scarce.

“Right now, there is so much demand and competition for supplies that the price is very high, and I cannot imagine that changing anytime soon,” Mr. Clarkson said.

He estimated that farmers in the United States were producing about six million bushels of organic soybeans, for example, when some 20 million bushels are needed to meet current needs. Organic soy is selling for $25 to $30 a bushel, Mr. Clarkson said, or about twice the price of regular soy beans.

The amount of land devoted to organic farming has grown, according to the Agriculture Department, but not nearly enough to address growing consumer demand.

“Younger people are much more interested in the chemistry of their lives, and so for them the issue of pesticides is a troubling one,” Mr. Clarkson said.

Ultimately, however, Walmart’s move could increase the supply, and eventually bring prices down.

The online grocery retailer Fresh Direct has an extensive selection of organic products among its overall merchandise mix. A five-pound bag of conventional russet potatoes was selling for $3.99, while its organic counterpart was $5.99. A box of Driscoll’s organic strawberries is usually a dollar more than its conventional brethren.