Legendary global investor Jim Rogers believes agriculture will be the next big thing over the coming 20 years. And it's an easy call: the United Nations is freaked out about food security, with supplies dipping to historic lows in the face of an ever-increasing population, or demand.

With less arable land to service larger populations due to water scarcity and climate change, as well as top soil degradation (a topic that doesn't get enough attention if you ask me) because of concentrated factory farming, it doesn't take an agronomist to figure out that the world's food supply is in trouble. Moreover, even though certain fish stocks have bounced back to life, the oceans are quickly being depleted of the proteins they serve nearly one billion per day.

So from an investment perspective there is opportunity in the food scramble. The question is how to play it. For sure, don't use the mantra of environmentalists: "Buy local and think global." As a matter of fact, do the opposite and buy global.

Engendering small farmers in the developing world to get in on world trade will not only foster new social enterprises, decrease poverty, shore up food security, and kickstart better trade agreements, but also result in the investment likely serving you better.

Big-time investors are pouring money into the agricultural space in the developing world. They are getting in on ground-floor opportunities.

The Gates Foundation is investing huge in agriculture programs in Africa. It has even enlisted the investment firm Lions Head Global Partners out of London, comprised of former Goldman Sachs bankers, to syndicate a food investment program. Hedge funds such as Harvest Capital in the U.S. are also big believers in the agricultural sector (hence the name).

Rogers said in a recent Q&A with Steve Forbes in Forbes magazine that "there's going to be a huge shift in American society, American culture, in the places where one is going to get rich. The stock brokers are going to be driving taxis. The smart ones will learn to drive tractors so they can work for the smart farmers. The farmers are going to be driving Lamborghinis."

OK, maybe you shouldn't chuck your day jobs just yet. But when it comes to investing in food, it's worth a bite.