About 4 million households rely to some extent on farming in Thailand, of which 900,000 have joined the scheme, the foundation said.
The policy is seen as benefiting owners of large farms in particular as they have a bigger surplus to sell to the authorities after their own household consumption. The scheme has also been dogged by allegations of corruption.
The Thai government says it is confident that it can find buyers for its rice at a price that will raise the living standards of its farmers.
It says it has signed deals to sell rice directly to other countries.
Nigeria, Iraq, Indonesia, Ivory Coast and South Africa are the top customers so far this year, according to the Thai Board of Trade, which says exports slid 45 percent in the period between January and last month from a year earlier to 5 million tonnes.
“We’re still confident that we can keep releasing the rice that we have,” Thai Commerce Minister Boonsong Teriyapirom said.
However, not everyone is so optimistic.
“If the situation continues like this, you will see a lot of exporters gone out of business,” Chookiat said.