When it comes to the future of farming, growers have two choices: Take it upon themselves to implement sustainable practices, or expect someone to force them to. That’s the message philanthropist and no-tiller Howard G. Buffett shared last week at the 6th World Congress On Conservation Agriculture in Winnipeg, Manitoba.

And the pressure may not just come from the government. Buffett explained that big corporate food companies are trying to figure out how they can ensure the food they use in their products was grown sustainably.

“If Coke wants to buy fructose and they want to say it comes from a sustainable farm production process, they can’t do that today,” he says. “There are 100 other companies, they’re all thinking about, ‘How are we going to know — because our shareholders demand it, our consumers demand it — that we have a sustainable process in place for the corn that produces fructose, or any other product?’”

Buffett, who currently serves on the corporate board of the Coca-Cola Co., says that currently, if a company buys his corn, they don’t know whether he no-tills, strip-tills, or applies 50 extra pounds of nitrogen that isn’t needed. But he expects that to change.

According to a report from Ceres, a nonprofit organization advocating for sustainability leadership, several national and international food companies, including General Mills and Kellogg, are “putting growing expectations on farmers in their supply chains to reduce fertilizer use and associated water pollution and greenhouse gases.”

One example is Wal-Mart, which recently set a goal to improve fertilizer-application efficiency of U.S. row crop farmers in its food supply chain by 30% by 2020. Another example is Coca-Cola, which last year announced its goal of sustainably sourcing all of its agricultural ingredients by 2020.

“It may come from regulation. It may come from corporate demand, or consumer demand,” Buffett says. “But it’s coming. And it’ll probably come slow enough we’ll have time to adapt. But you can’t stand still.”