It was a curious time for Sonny Perdue to close a real estate deal.

In February 2017, weeks after President Donald Trump selected him to be agriculture secretary, Perdue’s company bought a small grain plant in South Carolina from one of the biggest agricultural corporations in America.

The AGrowStar transactions were first flagged to The Post by the government watchdog Accountable.US, which is calling for Perdue to be investigated.

The group’s president, Kyle Herrig, called the deal “the definition of corruption.”

“Perdue must be held accountable for putting his own interests — and those of one of the most powerful corporations he oversaw — ahead of consumers, family farmers and rural America,” he said.