Attaining the highest level of efficiency associated with the application of fertilizer N in an irrigated cotton (Gossypium spp.) production system is important agronomically, economically, and environmentally. The objective of this project was to evaluate the affect of time of application on the uptake and recovery of fertilizer N in a furrow irrigated cotton. Field experiments were conducted using Upland cotton (G. hirsutum L., var. DP 20) at the University of Arizona Marana Agricultural Center on a Pima clay loam (Typic Torrifluvent). Three treatment regimes consisted of varied times of application (pinhead square, early bloom, and peak bloom) of ¹⁵N labeled fertilizer as (¹⁵NH₄)₂SO₄ with 5 atom % ¹⁵N at a rate of 56 kg N/ha/application. All treatments received a total of 168 kg N/ha from the three dates of application, with the ¹⁵N labeled applications occurring at only one date of application. At maturity, entire plants were collected and analyzed for fertilizer N uptake. Soil samples were collected at the end of the season from the center of the microplot areas to a depth of 1.8 m by 30 cm increments. In general, plant uptake and recovery of fertilizer N increased with later dates of application, coinciding with higher periods of N demand. However, plant uptake and recovery estimates of fertilizer N and lint yields were not significantly different as a function of time of application. Most of the fertilizer N that was recovered in the soil was found in the top 30 cm. Over 95% of the fertilizer N in the soil was recovered in the top 60 cm. Total fertilizer N recoveries (plant + soil) averaged 86.43% among the three treatments, with no significant differences among treatments. Of the total fertilizer N that was recovered, approximately 40% was taken up in the plant and approximately 60% was recovered in the soil. Therefore, applications of fertilizer N between pinhead square and peak bloom stages of growth are capable of achieving equal levels of efficiency in an irrigated cotton production system.