So much for my theory that a company should be able to hit a bull's-eye on its earnings per share if it updates its guidance just a week before its actual financial statement comes out.

Fortunately -- or maybe intentionally -- Monsanto (NYSE: MON) guided on the low end of where things actually ended up. Excluding a one-time payment from its spinoff Solutia (NYSE: SOA), Monsanto earned $1.79 in its fiscal second quarter -- $0.04 better than it had previously guided.

Even if it was an earnings "surprise," the general upswing of revenues and gross margins shouldn't be a big surprise to anyone who's followed the company. Revenues were up 45% year over year, and gross margins jumped to 59%. Much of this incredible growth has come from higher corn seed sales, as farmers have ramped up production to feed the ethanol beast.

Surprisingly, even with corn prices high, farmers are moving away from planting corn this year because of high fertilizer costs. Instead, they're focusing on soybeans, which require less fertilizer. That could hurt fertilizer makers like Mosaic (NYSE: MOS) or Potash (NYSE: POT), but Monsanto isn't worried. It has the soybean seed market wrapped around its finger, so any shift in acres planted mostly just shifts revenues from one line to another.

Ultimately, seeds are where Monsanto's long-term growth lies. It's looking for gross profits from RoundUp and other herbicides to be relatively flat between this fiscal year and 2012, but expects 15% to 18% growth in gross profits from seeds over that timeframe. As it stacks multiple traits into one seed and introduces new ones, it expects to be able to take market share away from fellow seed producers like Dow Chemical (NYSE: DOW) and Syngenta (NYSE: SYT) and fetch higher prices, to boot.

Considering the profits Monsanto has produced over the last few years, it's not surprising that investors are pricing it like a growth stock. But unless the commodity bull market goes on forever, I'm having trouble getting excited about it at these prices. The company has a strong future with its seed business, but that alone is not a good enough reason to buy.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Dow Chemical is an Income Investor pick. Read the Fool's disclosure policy; it'll grow on you.