Would-be participants in the "soy dollar" program need more details, several told Reuters.
Spot market transactions under the latest version of the policy, which initially kicked off last year, showed no movements on Monday, according to traders.
"It started quite calmly with few offers from factories in a very cautious market waiting for more information," said Eugenio Irazuegui, a researcher with brokerage Enrique Zeni y CIA.
Only about 17.5% of the 2021/22 soybean crop of some 44 million tonnes remains in local storage, according to official data at the end of March.
Meanwhile, about 5.5 million tonnes of soybeans from the current 2022/23 harvest, which has only just begun, have been sold, official data showed, compared to about 12 million tonnes at the same time during the year-ago period.