EMISSIONS OF N2O AND NO AND NET NITROGEN MINERALIZATION IN A BOREAL FORESTED PEATLAND TREATED WITH DIFFERENT NITROGEN-COMPOUNDS

Fluxes of nitrous oxide (N2O) and nitric oxide (NO) were measured on a drained and forested peatland in 1992-1995. Net mineralization and ni trification were studied in situ in 1993-1994. Nitrogen additions in 1 992 as KNO3, NH4Cl, or urea (100 kg N.ha(-1)) were used to study the f ate and transformations of N in peat. The mean N2O emissions during th e growth season in 1993 were 1.9, 2.6, 3.3, and 3.5 mg N.m(-2).day(-1) in the control soil, KNO3, NH4Cl, and urea-treated soils, respectivel y. Mean NO fluxes during the growth season in 1993 averaged 0.3, 0.4, 0.7, and 0.6 mg N.m(-2).day(-1) in the control soil, KNO3, NH4Cl, and urea treatment, respectively. Annual net N mineralization was 87 kg N. ha(-1) in the control soil and 107, 129, and 91 kg.ha(-1) in the KNO3, NH4Cl, and urea-treated soils, respectively. Added N increased the fl uxes of N oxides at least for a year after the treatments. The study s howed that forests on drained N-rich peat soils may be significant sou rces of N2O and NO and that their production of nitrogenous trace gase s is enhanced by additional N.