A multi-year study was established at the Delta Research and Extension Center to evaluate cotton response to residual nitrogen (N) and potassium (K) applied to corn.  Half of the research area has been planted to corn each year and the remaining half planted to cotton.  Corn N rates ranged from 134 to 336 kg ha^-1 in 34-kg increments as urea-ammonium nitrate solution (32% N). Potassium was applied at rates of 0, 34, 67, and 101 kg K ha^-1 as liquid muriate of potash.  The N and K rates were only applied to the area when it was planted to corn.  The following year, a uniform N rate, 101 kg N ha^-1, was applied to the cotton with no additional K.  In the initial year of the study (2004) corn yields ranged from 9.7 to 10.3 Mg ha^-1 with no significant yield increase achieved with N rates above 202 to 235 kg N ha^-1.  In 2005, cotton yields following the previous corn crop ranged from 968 to 1011 kg lint ha^-1 with no significant difference in yields as they related to the previous year=s N rates.  Corn yields of 10 Mg ha^-1 removed about 140 kg N ha^–1 from the field as harvested grain.  Corn yields in 2005 ranged from 12.4 to 13.0 kg ha^-1 with the most optimum N rate at 202 kg ha^-1.  Cotton yields were higher in 2006 and ranged from 1474 to 1538 kg lint ha^-1 with no yield difference related to residual N.  Corn yields were higher than in previous years with grain yields ranging from 12.9 to 14.2 Mg ha^-1 with the highest yields obtained with 235 kg N ha^-1.  Similar trends are evident for 2007.  Biological transformation, nitrification and denitrification, have generally led to N loss from the soil profile.