Evaluation of Nitrogen Management with ESN-Urea-UAN Combinations for Optimum Irrigated Continuous Cotton

Nitrogen management has been a research topic for many years in the Mississippi Delta in both irrigated and rain-fed conditions.  Most recently emphasis has been center on investigating more non-traditional nitrogen sources and additives compared to urea (46-0-0) and urea-ammonium nitrate solution (UAN, 32%N).  Environmentally Smart Nitrogen (ESN) is urea with a polymer coating that helps control the release rate of the urea-N.  It has been used successfully in wheat and other crops and has been evaluated for multiple crops in the South including corn, cotton, and rice.  The characteristics of the granular allow for a slow release as water is taken into the particle, urea dissolved, and released.  For some crops the release time may be too slow and thus requires a more soluble source early in the growing season.  The study was designed to have all nitrogen applied early in the growing season as 1) 100% ESN, 2) 100% Urea, 3) 100% UAN, 4) 50% ESN + 50% Urea, or 5) 50% ESN + 50% UAN.  These systems were applied at rates of 60, 90, 120, and 150 lb N/acre.  Both ESN and Urea were applied to the soil surface after cotton emergence and incorporated by cultivation while UAN solution was band applied by rolling coulter on either side of the planted row.   Results will be reported for at least three years of research.