When you've been around for a couple of centuries -- which even I can't claim -- and have earned your spurs in often arcane science and technology, it has to be tough to head back to the farm. Unless, of course, that's where the real money is.

That appears to be the case with DuPont (NYSE: DD), the big Delaware-based chemicals company that's seeing its agricultural businesses flourish to such an extent that management has strengthened the company's earnings expectations for both 2007 and 2008. For last year, the hike is actually an affirmation that results will likely come in at the upper end of the company's previously announced range. But for '08, management has tacked on a few pennies at either end of its guidance range.

All this is perhaps the continuation of a trend that's already shown itself at the company. In the quarter ended in September, for instance, DuPont's agricultural and nutrition unit increased in revenues more than three times that of any other unit. The segment benefited from worldwide increases in seed corn demand -- an ethanol beneficiary for Fools to ponder -- along with an increasing appetite for soybeans and canola. In Latin America, which chalked up a nearly 25% jump in sales, and in Europe, the company is peddling lots of fungicides.

This isn't to say that DuPont has moved away from its more traditional businesses. Indeed, on Thursday, the company announced the start-up of a performance coatings plant in Shanghai, China. The plant will crank out -- probably not an ideal term for a chemicals facility -- products that'll be used largely on trucks and heavy equipment in the region.

It's important that DuPont's dug a deep furrow in agriculture that, along with a global spread that takes it into 70-plus countries, renders the company compelling on a couple of fronts. Of course, Deere (NYSE: DE) offers a similar combination through its farm equipment products. And beyond that, there are other ways to play the hot ag markets. For instance, fertilizer manufacturer Mosaic has grown like a weed, and Monsanto (NYSE: MON) has gone to seed to the extent that its shares are up about 140% in a year.

The key, it seems to me, is that the business of feeding the world's increasing billions of mouths won't -- almost can't -- pull back. When you can profit from that truism, while also benefiting from the ongoing strength of many of the world's economies, all the better. DuPont appears to offer that double-barrel prospect.

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Fool contributor David Lee Smith owns neither a chemistry set nor -- unfortunately -- any shares in any of the companies mentioned. He does welcome your questions or comments. The Fool has disclosure policy.