SIOUX CITY, Iowa (AP) - A judge has sentenced a former manager at one of the nation's largest grain cooperatives to 51 months in prison for accepting bribes from an Iowa farmer in exchange for deep discounts on products. U.S. District Judge Mark Bennett issued the sentence Tuesday in Sioux City to former West Central Co-Op sales manager Chad Hartzler. Bennett ordered Hartzler to pay the Ralston-based cooperative $2.5 million in restitution. The 51-month term had been recommended under a plea agreement in which Hartzler pleaded guilty to wire fraud last year. Hartzler has admitted to taking $480,000 in bribes from Lake View farmer Bill Wollesen starting in 2005. In exchange, Hartzler says he secretly gave Wollesen discounts on crop seed and farm chemicals. Wollesen hasn't been charged and denies the payments were bribes.