Value of copper, zinc, and oxidized charcoal for increasing forage efficiency of urea N uptake

Gelton G.F. Guimarães, Richard L. Mulvaney, Reinaldo B. Cantarutti, Breno C. Teixeira, Leonardus Vergütz

Research output: Contribution to journalArticlepeer-review


Volatilization losses reduce the efficiency of surface-applied urea for crop N uptake, and can be controlled using urease inhibitors to retard hydrolysis or by the presence of other amendments that enhance retention of NH4+ formed by urea hydrolysis. A greenhouse study was conducted to evaluate the effectiveness of oxidized charcoal (OCh; 150 g kg-1 fertilizer) applied with or without Cu and/or Zn (~0.5-2 g kg-1 fertilizer), and of Cu and/or Zn applied without OCh, for increasing uptake of urea 15N by a common tropical pasture grass, capim-Mombaça (Panicum maximum Jacq. Cv. Mombaça), grown on a coarse-textured Oxisol. Cuttings were collected 5, 14, 28, 42, and 56 days after surface placement of amended or unamended urea pellets to estimate dry matter production, total N uptake, and 15N recovery. Soil sampling was carried out in conjunction with the first and fourth cuts to evaluate exchangeable NH4+ and NO3- concentrations. At the concentrations studied, OCh was more effective than Cu and/or Zn for prolonging NH4+-N availability in urea-treated soil; however, OCh alone or in combination with Zn and Cu had no effect on biomass production or N recovery and can safely be eliminated as a useful option for pasture improvement. The most promising amendment was Zn, which significantly increased total N uptake and the efficiency of urea N fertilization. The use of Zn in conjunction with urea has practical potential to improve forage production on tropical soils.

Original languageEnglish (US)
Pages (from-to)157-165
Number of pages9
JournalAgriculture, Ecosystems and Environment
StatePublished - May 15 2016


  • Forage production
  • N
  • Urease inhibitors
  • Zn fertilization
  • Zn-N synergism

ASJC Scopus subject areas

  • Ecology
  • Animal Science and Zoology
  • Agronomy and Crop Science


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