Previous research has shown widespread incidence of high residual nitrate concentrations in soil profiles in all cotton production regions of Texas. This research also documented that at least a portion of this nitrate should be subtracted from fertilizer N recommendations to achieve a given yield goal, thereby reducing N fertilizer application rates. Field studies utilizing 15N-enriched fertilizer was conducted with cotton in 2006 and again in 2007 to address availability with depth and how nitrate-N credits may influence fertilizer recommendations. 15N-labeled Ca(NO3)2 was applied at a rate of 20 lbs N/acre in microplots at the following placement depths: surface, 6, 18, 30, and 42 inches. Controls that received no nitrogen fertilizer were also included. Plants from microplots were sampled on July 11th and August 8th. Plant segments were analyzed for total N and 15N concentrations by ratio mass spectrometry. Uptake efficiency for 15N-labeled Ca(NO3)2 in the first harvest was greatest for surface-applied fertilizer (82%) and lowest for fertilizer applied at a depth of 42 inches (9%). Fertilizer uptake efficiencies were lower in the second compared to the first harvest possibly because of leaf senescence, as well as decreased nitrogen concentrations in all plant parts in the second harvest. As opposed to other depths, fertilizer uptake efficiency for nitrogen placed at 42 inches increased from 9% in the first harvest to 28% in the second harvest, implying that cotton may utilize nitrate at deeper soil depths as the growing season progresses, especially if sufficient nitrogen is not available at shallower depth. This year's research findings and producer soil sampling recommendations will be discussed.