Seed company Monsanto Co. said Wednesday its second-quarter earnings more than doubled on increasingly strong sales of corn seed and herbicide in the United States. But the company's profit forecast for 2008 appeared to disappoint Wall Street as the company's shares slipped by midday.

Monsanto earned $1.13 billion, or $2.02 per share, in the three months ended Feb. 29 from $543 million, or 98 cents per share, in the prior year. Its revenue jumped 45 percent to $3.8 billion from $2.6 billion in the prior-year period. The company said corn seed sales were a standout during the quarter, jumping to $1.7 billion from $1.2 billion during the same period a year before.

The results surpassed the expectations of analysts surveyed by Thomson Financial, who predicted earnings of $1.72 per share. The analyst estimates typically exclude one-time items.

For the first half of the fiscal year, Monsanto earned $1.39 billion, or $2.48 a share, up from $633 million, or $1.14 a share, a year earlier. Six-month revenue rose to $5.88 billion from $4.15 billion.

The company forecast 2008 profits of between $3.15 and $3.25 a share on an ongoing basis. Analysts polled by Thomson Financial had predicted earnings of $3.20 a share. Monsanto's shares fell $1.45, or 1.3 percent, to $111.50 in midday trading after falling as low as $105.84 earlier in the session.

Monsanto attributed the sales growth to increases in corn seed and traits revenue in the U.S., as well as higher sales of Roundup and similar herbicides in North America, Europe and Africa.

"Between now and 2012, we are the only agriculture company that can point to consistent growth irrespective of commodity price swings, fluctuations in planted acres or the popularity of ethanol. Over the next five years we're poised to set the bar higher as we deliver a game changing platform every other year, real products that create real value for the farmer and for our shareowners," Monsanto President and Chief Executive Officer Hugh Grant said in a statement.

Monsanto earned $1.79 per share in its last fiscal year ended Aug. 31.

Monsanto aims to double its gross profit potential by the end of 2012. It plans to do that by focusing on corn, soybeans, cotton and vegetable seeds. Prices for commodities like corn have surged due to strong global food demand, the ethanol industry and a weak dollar.