The American Soybean Association reports that the Senate voted in favour of the bill by a margin of 53-2 with three abstentions. The bill now returns to the lower house, which cleared the original proposal in February.
Last year Brazilian President Luiz Inácio 'Lula' da Silva granted a temporary authorisation for GM soy plantings while a bill on the planting of controversial GM soy in Brazil went through the parliamentary process.
A key competitor with the US, Brazil is a leading global supplier of soybeans, and total soy business for the country represents a hefty 32 per cent of Brazilian farm trade. About 75 per cent of its yearly crop is shipped to Europe, where health conscious consumers have been the most resistant to GM. However the seed producers association Abrasem estimates that Brazilian farmers planted almost 6.4 million hectares with GM soybeans last season.
According to the ASA the most controversial changes to the bill relate to who will have the ultimate say over the approval of biotech crops in Brazil.
"The new text effectively puts these decisions in the hands of a body of scientists called the CTNBio [Brazil's regulatory committee on biotechnology], which had originally been lined up for a more advisory role," reports ASA.
Anti-GM groups argue this change takes the decision out of the hands of elected representatives. "The CTNBio will end up having more power than ministers, imposing its decisions on the health and environment ministries," said Ventura Barbeiro of Greenpeace's genetic engineering division.
Defenders of genetically modified soy crops claim that farmers are attracted by savings offered by these crops, that need less application of herbicides and less fuel to power machinery for routine field work.