Farmers will have to pay about 42% more from 2010 for Monsanto Co.'s new genetically modified seeds Roundup Ready 2 Yield. These soybeans will cost farmers an average of $74 an acre, Bloomberg reported.

The original Roundup Ready soybeans will cost $52 an acre. Roundup Ready 2 Yield soybean seeds were planted on 1.5 million acres this year with acreage forecast to reach 8 million acres next year in the U.S. 

SmartStax corn seeds, developed with Dow Chemical Co., will cost $130 an acre, 17% more than the YieldGard triple-stack seeds they will replace. SmartStax corn seed will be planted on as many as 4 million acres in 2010, its first year on the market.

The new seed boosts yields 5-10% compared with other products, partly by reducing the amount of land that must be planted with conventional corn to 5% from 20%, Monsanto said.