Nitrous oxide (N₂O) is one of the most important greenhouse gases emitted mainly from biotic sources (Duxbury et al. 1993). Soil can remove atmospheric N₂O under conditions favorable for N₂O reduction (Letey et al., 1981; Smith at al., 1983; and Wlodarczyk et al., 2002, 2004). The main purpose of this study was to estimate the potential ability of soils to produce N₂O under flooded conditions where NO₃^- content was a non-limiting factor (100 mg NO₃^--N per kg corresponding to 300 kg NO₃^--N per ha in 20 cm top soil layer) and a potential ability of soils to consume N₂O. N₂O evolution and consumption in Calcaric Regosols developed from sandy and silty loam (No 543 and 922) depending on nitrogen addition and kind of soil were studied. Soil samples from Ap horizons (5 g dry soil with 4.5 ml distilled water and 0.5 ml of solution of nitrogen like a KNO₃, NaNO₂ and (NH₄)2SO₄ in concentration 100 mg/kg) were incubated with addition of N₂O (1% v/v) in tightly closed 60 cm³-glass flasks at 20^oC for 26 days. Soils without N₂O amendment were control variants. Gas concentrations (N₂O, CO₂, O₂ by gas chromatograph) were measured during incubation in three replications.

Table 1. Maximum and daily N₂O release and consumption

Treatment	N2O-N mg kg-1
	Sandy loam (No 543)				Silty loam (No 922)
	Release		Consumption		Release		Consumption
	max	daily	max	%	max	daily	max	%
Soil + H2O	0	0	0	0	0	0	0	0
Soil + NO3-	32.2	5.37	3.44	10.7	93.2	10.36	93.2	100
Soil + NO2-	43.0	1.65	0	0	28.7	1.43	0.95	3.3
Soil + NH4+	1.99	0.33	0	0	0	0	0	0
Soil + N2O	0	0	70.6#	45.3	0	0	167.3##	100
Soil + N2O + NO3-	19.1	6.37	13.1	7.2	70.4	7.82	231.6	99.3
Soil + N2O + NO2-	24.3	3.46	5.10	2.7	18.7	4.67	26.9	15.2
Soil + N2O + NH4+	2.45	0.61	77.1	47.5	1.46	0.24	162.0	100

^# - 70.58 mg kg^-1 /26 days = 2.72 mg kg^-1 d^-1

^## - 167.32 mg kg^-1/13 days =12.9 mg kg^-1 d^-1

In conclusion we can state that: (a) soil texture and kind of nitrogen addition affected significantly the N₂O evolution and consumption, (b) two investigated soils showed an ability of nitrous oxide consumption by soils without nitrate amendment - 2.72 for sandy loam and 12.9 mg N₂O-N kg^-1day^-1 for silty loam, (c) the ability of nitrous oxide consumption by the two investigated soils was higher than their capability of N₂O evolution.

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