Nitrogen (N) fertilizer is required for cotton fiber production, but the optimal N fertilization rate varies with soil and landscape characteristics within a field. In this study uniform rates of N fertilizer (0 to 150 lbs. N/acre in 30 lbs./acre increments) were applied side-by-side in field-length strips (15 ft wide by 1000 ft long). The optimal N fertilization rate was calculated for the six N rate (15 ft by 50 ft) harvested sub-blocks. For the field studied this created 36 individual N-response trials that were used to investigate spatial patterns in optimum N rate. For two site-years (1998 and 1999) we saw a 10X variation in lint yield–N. Statistical analyses showed that lint yield plateaued at the 90-100 lbs. N/acre increment. N treatment clearly affected yield, but soil conditions sometimes were more important in determining final yield. In this study effects of N treatments on cotton lint yield often were obscured by other yield-controlling factors.