Two years of falling rubber prices have driven many farmers into debt, with some saying they can't cover the costs of fuel and fertilizer.
"This was our last resort, our only option," said rubber farmer Thaworn Ruengkling. "We can't take it anymore."
Thai police tried and failed to remove the blockade.
Rubber prices have declined by more than 45 percent in two years after an economic boom in Asia in rubber, palm oil and coffee, The New York Times reported Thursday.
Farmers expanded production while rubber was in high demand, but now are producing too much of the crop while demand is slack, the newspaper said.
Bridget Welsh, a researcher and expert on Southeast Asian politics based in Singapore, said the protests would likely be repeated in Malaysia, Indonesia and Vietnam, countries where the government relies on rural support.