Evaluation of Polymer Coated Urea As An Alternative N Source for Cotton.

Nitrogen loss via denitrification, volatilization, and/or leaching can be great (50% of total-N applied) due to environmental conditions at application or if N applications are mismanaged.  Enhanced-Efficiency fertilizers could potentially reduce N loss in Mid-South cotton production systems.  The research objective was to evaluate cotton lint yield and fiber quality as affected by polymer-coated urea applied alone or blended with urea compared to application of urea alone.  Experiments were established during 2011 at the Delta Research and Experiment.  Environmentally Smart Nitrogen (ESN), Urea, or ESN:Urea blends were applied at 4 N rates ranging from 0 to 134 kg ha^-1 immediately prior to planting (AP) Stoneville ‘5288 B2F’ or at the 4-leaf (4LF)stage of cotton growth.  Nitrogen applications were incorporated at both application times with a furrow cleaner.  Seedcotton yield was determined by mechanically harvesting the middle two rows of each plot.  Lint yield and fiber quality data were based on hand harvest 50 boll samples from each.  The experiment was arranged as a randomized complete block with an 8 (N Strategy) × 3 (N Rate) factorial treatment structure and compared to an unfertilized control (0 kg N ha^-1).  Cotton Lint yield was not influenced by the main effect of N rate (p=0.9894), however was influenced by the main effect of N Strategy (p=0.0034).  Lint yield from the untreated control averaged 1229 kg lint ha^-1.  Averaged across N rates, cotton lint yield from treated plots ranged from 1232 (1/3 ESN-AP) to-1417 (1/3 ESN-4LF) kg lint ha^-1.  1/3 ESN-AP yielded statistically similar to urea-4LF and 2/3 ESN-AP treatments.  Fiber quality parameters were unaffected by N Strategy, N rate, or their interaction. ESN shows promise as an N management tool, however additional research is needed to determine if Environmentally Smart N or ESN:Urea blends are suitable N management strategies for Mid-South cotton production.