New corn hybrids increase yield and may change potassium (K) uptake or fertilization needs through improved traits that increase yield and root efficiency. Hybrids, soil conditions, and rainfall may affect the rate at which K in cornstalks is released to the soil and becomes available to plant uptake. Therefore, a study was conducted from 2006 through 2009 at the Agronomy and Agricultural Engineering Research Farm to evaluate the effects of K fertilization and rootworm resistance on grain yield, K uptake, and K recycling with residue.