Effects of Enhanced Efficiency Fertilizers on Cotton Growth Characteristics

Use of enhanced-efficiency N fertilizers (EENFs) in row crop agriculture has not been well studied despite increasing interest in these N sources to increase crop yield while decreasing N loss. A field study was conducted in Central Alabama from 2009 to 2011 to compare EENFs to standard N sources in a high-residue conservation cotton production system. Nitrogen fertilizers evaluated were: urea; ammonium sulfate; urea-ammonium sulfate; controlled-release, polymer-coated urea (Environmenally Smart Nitrogen, ESN); stabilized urea (SuperU); poultry litter; poultry litter + AgrotainPlus; and an unfertilized control. Detailed plant growth characteristics were determined before defoliation. Generally, standard fertilizers resulted in the largest number of bolls and the highest boll dry weight. ESN tended to perform as well as the standards. Both poultry litter treatments performed poorly during the first year; however, poultry litter + AgrotainPlus was similar to the standards by the third year of study. In this study, the more expensive EENFs produced yields similar to those of standard fertilizers, suggesting that the former may be economically impractical at present. However, EENFs could become viable alternative fertilizer sources given their ability to reduce N loss from agricultural fields via leaching, runoff, and nitrous oxide flux. Additional research is needed on the benefits of EENFs in row-crop