Corn silage and grain yields have steadily increased since World War II with a slightly greater increase per year for corn grain than for corn silage, possibly reflecting an emphasis on corn grain improvement by plant breeders in the past decades. With an increase in yield comes the question: Has the ability of improved crop varieties to explore the soil for nutrients kept up with higher yield or do we need to supply more N fertilizer to meet N needs? Further, we need to look at what differences in field traits (within and between) affect yield beyond the hybrid selected and the N fertilizer or manure that was applied. Nationwide evaluation of N use shows that overall farmers are using the same average fertilizer N rates, even while yields have been increasing. How are we doing in silage production areas such as New York State?