PWO president Chanudpakorn Vongseenin went to meet DSI director-general Tarit Pengdith at DSI head office on Friday to discuss how to address alleged irregularities in different crop schemes.
"The PWO has come across many corruption cases as reported by the media," Mr Chanudpakorn said.
"We would like to discuss them with relevant agencies, including the DSI and the Royal Thai Police, and seek ways to oversee and prevent corruption in the schemes."
The PWO would dispatch personnel to inspect areas where corruption might occur, he said.
DSI chief Tarit said there had been corruption problems with many crop schemes, especially rice, cassava and corn.
"I've been told that corruption is widespread in some of the provinces," Mr Tarit said. "From now on, firm action will be taken against offenders."
Mr Tarit said he had instructed Col Pinit Tungsakul, a special case expert, to lead the investigation.
DSI personnel will visit different provinces and conduct intensive investigations shortly, he added.
Reports said the PWO has submitted documents to the DSI suggesting that fresh corn was being substituted with rotten produce at warehouses in Tak province, with the good corn being taken to be sold at market.
A PWO official working on the case was also murdered, reports said.