The Response of Cotton (Gossypium hirsutum L.) to Slow Release Foliar Fertilization and the Effect of Environment on Absorption

In cotton production, nitrogen (N) is the most limiting nutrient and the demand is substantial. Foliar-N fertilization is regarded as an effective and environmentally sound method of supplying cotton with N during times of deficiency and high demand. In response to the potential benefits of the foliar-N fertilization of cotton, a myriad of foliar-N based fertilizers have been created; each with their own individual chemical technology and constitution. Experiments were performed with the objectives of examining the effects of the slow-release foliar-N fertilizer, NitaminRTM (1) on the growth and development of field-grown cotton, (2) on uptake under various environmental conditions, and (3) the quantification of foliar-N leaf absorption over time. Results suggested that Nitamin was not effective in high temperature stress conditions, but was effective in increasing yields in more temperate conditions/environments and in conditions of limited soil-N fertility. Additionally, Nitamin was found to have a slower translocation rate of foliar-N through the leaves when compared to foliar urea in all environmental stress conditions tested that was attributed to its slow-release technology. Nitamin was also found to have a high rate of leaf absorption when compared to foliar urea and urea ammonium nitrate (UAN 32) that was attributed to its viscous nature in increasing leaf surface retention. In general, the advantages of Nitamin for leaf absorption and retention was offset by non-significant and sometimes numerically lower values in many growth parameters when compared to foliar-applied urea in the majority of these trials, indicating that the short application window afforded by cotton may not be conducive for slow-release foliar-N fertilization in the absence of rainfall.