On his 1,000-acre west Kansas farm, Bryce Stephens said he makes a decent living raising cattle and certified organic crops like wheat and alfalfa.

But Stephens said he worries about crop contamination and the specter of infringement lawsuits from owners of patented genetically modified seeds that might turn up in his fields. Those concerns, he said, forced him to give up his corn crop and to start harvesting his own alfalfa seed.