With advances in genetic improvement of corn, yield levels continue to rise. Analysis of the KSU Irrigated Corn Hybrid Performance test data for the years 1968-1999 show that yields have increased by an average of over 20 bu/year. New hybrids suffer less yield reduction under conditions of drought stress, insect infestations, and high plant population. Newer hybrids have the ability to increase yields in response to higher plant populations. For many reasons, both environmental and agronomic, reduced tillage production systems are growing in use by producers. Resent research from the mid-west indicate that in reduced tillage systems K response can be achieved even though soil test levels are adequate.