Effect of Fertilizer Enhancers in Forage Bermudagrass Production.

Effect of Fertilizer Enhancers in Forage Bermudagrass Production

R. Lemus, J.I. Morrison, J. Varco and D. Lang

Due to increasing problems associated with the handling of ammonium nitrate (storage and transport), urea-based products such as urea (46-0-0), urea ammonium nitrate solution (UAN) (28-32%) and urea ammonium sulfate (33-0-0S) are becoming more popular in forage production systems.  One disadvantage of these fertilizer products is that they are more susceptible to volatilization losses under Mississippi's hot and humid summer conditions.  These nitrogen losses may be reduced by using enhancement products commonly known as “urease inhibitors”.  These fertilizer additives can be applied to dry or liquid urea-based fertilizers.  The objective of this study was to evaluate forage biomass production effects and fertilizer use efficiency of these enhancers and estimate their economic benefits in forage production systems.  The study was conducted on a 10-year old stand of Sumrall 007 bermudagrass with 1.82m x 2.43m plots.  The experimental design was a randomized complete block design replicated three times.  Fertilizer treatments consisted of a control and four fertilizer sources: ammonium nitrate (AN), urea (U), urea-ammonium sulfate (UAS) and urea ammonium nitrate [UAN (32% solution)].  Urea and UAN were treated with three fertilizer enhancers [Agrotain (AT), Environmentally Stable Nitrogen (ESN) and Nutrisphere-N (NN)].  AN and UAS were used along with the control as checks only.  Nitrogen was applied at a recommended rate of 224 kg N ha^-1 yr^-1 and at 75% and 50% of the recommended rate.  Nitrogen was applied in split applications of 56, 42 and 28 kg ha^-1, respectively, within the first four harvests.  Plots were harvested on a 4 to 5 week interval.  Yields were recorded and subsamples were taken for dry matter and nitrogen use efficiency determination. Data was analyzed using PROC GLIMMIX of SAS and means were separated by Least Significant Differences (LSD) at α = 0.05.  A linear decrease in yield was observed with decrease in nitrogen rate.  Use of fertilizer enhancers slightly increased nitrogen use efficiency with AT having the greatest impact.