Monitoring the N status of the cotton plant (Gossypium hirsutum L.) and understanding seasonal demands for N has been shown to be important for the implementation of sound N fertilizer management strategies that contribute to maximum profit. Conventional methods used for sampling and analysis of soil and plant N status have required considerable time and expense. Additionally, information has been unavailable about comparisons of in-field instantaneous and analytical laboratory N sampling techniques including conventional methods, chlorophyll meter, and the cardy NO3-nitrogen meter. Eight treatment combinations of high or low soil N, high or low boll load, and with or without foliar-applied N were arranged in a split-split plot design with six replications. Tissue sampling (leaf and petiole), leaf chlorophyll content (SPAD 502), and Cardy measurements of petiole sap NO3-N

were collected weekly starting at first flower. Lint yield and yield components of all treatments were determined by hand harvesting two meters of row per plot. From first flower until five weeks after first flower, measurements of plant N status by all four methods displayed the same trend. The SPAD meter results showed showed a strong correlation with the two traditional methods of leaf blade N and petiole NO3-N. Similar results were found between sap (Cardy meter) NO3-N

and leaf N, and between sap (Cardy meter) NO3-N and dry petiole NO3-N. The hand-held chlorophyll meter (SPAD-502) and the Cardy meter appear to be acceptable tools for monitoring the in-season N status of irrigated cotton in Arkansas. Further field comparisons of these methods under different environmental conditions, i.e. drought, are needed.