Brazil was an early adopter of transgenic crops and more than 96 percent of its soya harvest is of GM varieties, which helped to transform the country into the world's largest soya exporter.
Biotech crops, such as corn, soyabeans and cotton, are genetically modified to resist pests or disease, tolerate drought or withstand sprayings of weed killers like glyphosate, the active ingredient in Monsanto Co's Roundup herbicide.
Wininton Mendes, co-ordinator of a program to promote use of conventional seeds run by Mato Grosso growers and the government agricultural research agency Embrapa, said doubts related to the impact of GM food on human health is one driver behind demand for conventional raw materials.
Proponents of biotech crops say the technology lowers the cost of food and helps farmers to manage pests and diseases more safely. But some consumers and environmental groups argue that GM crops boost pesticide use and pose threats to the environment and human health.
Mendes said that Mato Grosso's drive to plant more conventional soya is backed by three trading firms - including Amaggi SA, owned by the family of Agriculture Minister Blairo Maggi - which pay a premium. The other two traders are Imcopa International SA and Caramuru Alimentos SA.
The average premium stood at 12 reais per 60-kilogram bag of GM-free soya this season, he told Reuters.
Reintroduction of conventional soya creates a niche market for farmers with deep pockets, since non-GM crops require strict controls to avoid contamination during production and shipping, which may raise costs.
Encouraged by the premia paid this season, farmers may plant more non-GM soya in the next cycle, according to Daniel Ferreira, the superintendent of agricultural research agency Imea.
Endrigo Dalcin, who planted 1,500 hectares (3,700 acres) of GM-free soya this harvest, plans to almost double that in the 2017/18 crop. "Some farmers in Mato Grosso are already planting 100 percent GM-free thanks to the premium and international demand," Dalcin said.
However, for many farmers the difficulty remains the availability of seeds.
An estimated 13.6 percent of the 2016/17 soyabean harvest in Mato Grosso was conventional, according to agricultural research agency Imea. This was down slightly from 15 percent previously as Brazil's conventional seeds supply remains low, said Mendes, the conventional seed program co-ordinator.
Mato Grosso's program aims to give farmers "a choice," he said. Monsanto's RR and Intacta technology account for all the transgenic soya in Brazil, data sampled this season by consultant Agroconsult show.
Copyright Reuters, 2017