The gift is Purdue's largest-ever donation from individuals.
Purdue spokesman Chris Sigurdson says the anonymous couple pledged the money as an estate gift that will go to the school following their deaths.
He says the gift is currently worth $65 million but that will continue to grow. The money will come to the College of Agriculture without any restrictions.
Dean of Purdue Agriculture Jay Akridge says the donation "is truly a transformational gift" for the college.