In their memorandum to officials, they said potash cost was Rs 850 per bag and not Rs 550 a bag, as claimed by the agricultural department officials.
Though T Chockalingam a district official said potash cost was Rs 550, farmers said no dealer sold potash at that price.
They also alleged that the primary agricultural societies were selling very old stocks.
Officials instructed PACs to sell fresh stocks and said after receiving permission from factories, these stocks would be sold at rs 550 a bag.
Suggestions were also made to install CCTV camera in paddy procurement centres to curb irregularities.