Remember the TV commercial for E.F. Hutton, some 35 years ago? "When E.F. Hutton speaks, people listen."

In agriculture, when Dave Kohl speaks, people listen.

This winter Kohl made the winter speaking circuit with a message focusing on the key global indicators that could impact American agriculture. These factors led to the last grain supercycle, which has now faded. How will they play out in 2015?

"Don't bet the farm on trade with China," says Economist David Kohl.

Keep an eye on emerging nations. The BRICS – Brazil, Russia, India, China, and South Africa, along with South Korea, Indonesia, Mexico and Turkey – represent 26% of the world economy. From 2002 to 2012 they represented approximately half of the world's economic growth. Meanwhile, since 2008, While America's coastal urban centers went through the great recession, the Midwest did not feel it because we were selling farm exports to those nations, and they were growing at 8-11%.

"China used more steel in 2011-2012 than America did in the entire 20th century," says Kohl.

Now global growth rates have fallen below 4%, and China will come in around 5-6% growth.

What keeps China's leader Xi Jinping up at night? He worked hog farms for a decade, so the guy knows agriculture, says Kohl. "He's very worried about social disruption and that's easy to have in China where you have 800 million people living on $2 a day and the rest doing very well."

That's why Jinping is buying up assets. North Carolina-based Smithfield Foods, the world's largest hog processor worth $14 billion, was purchased in 2013 by Chinese firm Shuanghui Group. It's just one example.

"He knows he has to feed and clothe people and he knows China's Achilles heel is natural resources," says Kohl. "Over 20% of China's soil has so much toxicity that plants will emerge but won't yield. Air quality and water quality are both big problems."

For American farmers, this all translates to trade opportunity - and risk.

"Don't bet the farm on trade with China," he says. "China will giveth a market, but then they will taketh away." Case in point: when Chinese-made tires began blowing up on our highways and the U.S. banned them, China immediately stopped buying U.S. poultry.

Watch biofuels and ethanol. In 1998, only eight percent of the U.S. corn crop went to biofuels; Now it's 37%. The Renewable Fuels Standard was a game changer.

Now it's time to watch oil prices, because in every recession since 1969, oil has been a key indicator. When you start talking about $30 to $40 per barrel for oil, shale no longer becomes viable. "The Big Oil companies are sitting like vultures on the phone lines in North Dakota," says Kohl. "They will come in to buy out those energy folks at 50 cents on the dollar."

A $10 drop in the price of a barrel of oil means $25 million less in Russia's economy, which is headed for recession.

Central bank stimulus. To avoid a depression in 2008, then Fed chairman Ben Bernanke made moves to stimulate the economy and devalue the dollar, which all encouraged farm exports.

"Now we are taking our foot off the gas pedal while Europe and Japan are trying to mess with their currency," he says. "As the dollar strengthens as it has in recent weeks, it weakens our ability to export."

The Fed recently came out to say interest rates would remain at current levels for the time being. It has also said rates will likely go up some time this year. Kohl says 40% of U.S. farm land values are connected to central bank policy here and around the world.

"Much of agriculture is vulnerable on variable rate operating loans," he says.

Those rates have stayed flat eight years. Two of the three indicators Kohl monitors say interest rates will increase. Unemployment and GDP both indicate higher interest rates ahead; the third indicator, inflation, not so much. Core inflation right now is only 1.7% and the benchmark for change is 2.5%. (Agriculture's inflation rate has been clicking along at 5 to 8% the last several years while the general public inflation is less than half that.)

"With $4 trillion on the Fed's debt load we should be seeing inflation above 10%, but companies have been so confident because they are loaded with cash," says Kohl. "If the velocity of money picks up, watch for inflation to pick up as well."

Inefficient infrastructure in emerging nations. Countries like Brazil may have vast natural resources, but they lack ways to move product to market efficiently. The most recent trucker strike in that country is just one example of many in these emerging nations. Farmers in Argentina are hamstrung by a 38% export tax on soybeans. Often times emerging nation politics is the U.S. farmers' best ally.

Weather in northern and southern hemisphere. Keep your eye on both hemispheres because what happens in the south impacts the north. The U.S. is coming off two really good growing seasons; what are the odds of a third?

Livestock industry. "We got pretty arrogant in the grain sector when we forgot where our biggest market was – the mouths of cattle, pigs and chickens," says Kohl. "The economic health of the livestock industry is critical to grain."

In many respects you could see the livestock industry dwindle from drives through the country. Pastureland went into corn, dairy barns went empty, and hog houses were abandoned, not to mention withering drought in key cattle states.

"I was encouraging young farmers to go into livestock because it was an opportunity, but grain farming was the place to be," says Kohl. "Now, older farmers don’t want to come back into livestock, despite high prices.

"We're setting up for a couple good years, but it could drop off the table very quickly," he adds.