It's been said that stocks take the stairs up and the elevator down. When they're going up, the process can be painfully slow, but when they're falling it's as though there is nothing anybody can do to stop their descent. The declines can be so swift and frightening that it feeds on itself, inducing nervous shareholders to liquidate their shares for fear of being wiped out.

Case in point is Potash Corp. of Saskatchewan (POT).  Shares fetched $179 on 9/22/08. Today they're selling for $86.  There was no stock-split here, instead pure unadulterated selling. Ouch!

Not that many years ago companies in the agricultural chemicals industry were mere afterthoughts. The businesses were not sexy and didn't have a killer application or slick marketing departments like Apple, Google, Intel or any of the hundreds of other tech stocks that outperformed during the late nineties.

Fertilizer is just flat out boring. It is a market that fills a critical part of the food chain but is typically classified as a defensive stock, not a growth business.   Well, not until oil prices started rising rapidly.

Action in the oil markets combined with fears of global warming resulted in interest in alternative energy.  Solar and wind power are great, but they wont power our cars. Natural gas is cheap and abundant but requires drilling and drilling is a bad word.

That left ethanol as the alternative energy of choice that could make a difference now. Given that ethanol comes from corn it was only natural for farmers to begin planting more and more corn to supply demand. (See also: "Top Alternative Energy Plays.")

Price increases prompted farmers to plant more while searching for ways to increase yields.  Well, fertilizers helped improve yields and turn questionable land productive. Companies like POT suddenly had their own killer app.

Defensive fertilizer makers were now suddenly momentum stocks.  POT flew all the way to $250, but what goes up must come down.  Indeed revenue and profit growth justified the appreciation, but valuations became speculatively rich.

That being said a catalyst was needed to prick the bubble.