The Iowa Nitrogen (N) response trial database was updated March 24, 2009. Response trials were added from 2008 research and several trials from older research were removed. There are now 176 trials for corn following soybean and 78 trials for corn following corn. Being able to easily update the database with recent data is one of the many advantages to this dynamic approach for corn N rate guidelines. Having new response trial data allows rapid updating with changing hybrid genetics, rotations and climatic conditions.