Mosaic Co., one of the world's largest fertilizer makers, posted results Tuesday that fell well short of Wall Street's profit expectations, buffeted by soft demand in Asia and drought in the United States and elsewhere.

The Plymouth-based company reported fiscal first-quarter net income of $429 million, or $1.01 per share, down 18 percent from a year ago. Earnings were 14 cents per share below the average estimate of analysts polled by Thomson Reuters.

Mosaic's sales shrank by 19 percent to $2.5 billion, falling short of analysts' forecasts of $2.68 billion. The company's stock dropped $2.25, or 3.9 percent, closing Tuesday at $55.76.

CEO Jim Prokopanko said in a statement that drought and other weather-related issues in some of the world's key agricultural regions hammered corn, soybean and wheat crops, providing "a vivid reminder of just how tenuous global food security is."

The U.S. drought has hurt Mosaic in the short term, as farmers with damaged crops pull back on fertilizer use. But by next year, drought could boost fertilizer sales, as farmers look to increase yield to make up for 2012's shortfalls, particularly if commodity prices remain high.

Drought has depleted the wheat crop in Russia and rice crop in India, Prokopanko told stock analysts in a conference call. "Mother Nature has left much of the planet very thirsty, while also battering us with tropical storms, hurricanes and heavy rainfall in Canada."

Mosaic produces fertilizer from phosphate, mostly mined in Florida, and potash, primarily mined in Saskatchewan, Canada.

The company's phosphate sales were $1.6 billion during the quarter, down 30 percent from a year earlier, while phosphate operating earnings were down 38 percent. Lower prices were part of the problem. Also, a week of production in Louisiana was lost due to Hurricane Isaac, and low water levels on the Mississippi River -- a major bulk shipping artery -- hampered fertilizer shipments. To top it off, phosphate exports to India, a major market, were also down.

Soft demand from India and China also hurt the company's potash segment, though overall potash sales grew 10 percent over a year ago to $960 million. Mosaic's Potash operating earnings rose 4 percent over a year ago.

Staff writer Jackie Crosby contributed to this report. Mike Hughlett • 612-673-7003