Gaseous Nitrogen Losses from Gulf Coast Marshes

The low evolution of N2O and NH3 from unamended brackish and salt marsh soils suggests a conservative internal nitrogen cycle exists in Louisiana's coastal marshes. The gaseous evolution of NH3 and N2O increased following the addition of (NH4) 2SO4. The maximum rates of NH3 volatilization from the salt and brackish marshes were 5.7 and 3.2 mg N m_2 d_1, respectively. The corresponding total NH3 volatilization was 34 and 15 mg N m_2 for the salt and brackish marshes. Volatilization from unamended cores amounted to 6.0 and 0.9 mg NH3-N m_2 from the salt and brackish marshes. Approximately 29 and 15 mg N2O-N m_2 was evolved from the brackish and salt marsh sediment amended with 1243 and 1469 mg NH4+ -N m_2. The N2O evolution from the unamended cores was 0.4 and 2.2 mg N m_2 from the brackish and salt sediment.