Nitrous oxide production and consumption in Calcaric Regosols as related to soil redox and texture
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Institute of Agrophysics, Polish Academy of Soil Sciences, Doświadczalna 4, P.O. Box 201, 20-290 Lublin 27, Poland
Lublin University of Technology, Nadbystrzycka 40B, 20-618 Lublin, Poland
Int. Agrophys. 2005, 19(3): 263–271
The aim of this study was to investigate the effect of redox status on nitrous oxide (N2O) evolution and transformation in soils of various textures. Soils samples were collected from Calcaric Regosols (according to FAO/UNESCO) developed from sand, silt and loam across various regions in Poland and were incubated anaerobically for 35 days. The initial phase of N2O production, lasting 2-21 days, was followed by a gradual decrease indicating reducing of N2O. The total amount of N2O reached 13-44% of the initial nitrate-N (NO3--N) content and was highest in the silty soils and lowest in the sandy soils. It was negatively correlated with the >0.05 mm fraction and positively with the 0.05-0.002 mm fraction. Average daily N2O production was negatively correlated with the >0.05 mm fraction and positively with finer fractions ie with the 0.05-0.002 mm and with the <0.002 mm fraction. The rate of N2O disappearance averaged 0.56, 4.08 and 11.7 mg N2O-N kg-1day-1 in sandy, loamy and silty soils, respectively. Rate of N2O consumption and organic matter content for individual soils was positively correlated with the 0.05-0.002 mm fraction and negatively with the >0.05 mm fraction. N2O reduction to N2 begins earlier in finely (eg loam) than in coarsely textured (eg sand) soils. Nitrous oxide content in the headspace existed in equilibrium with the nitrous oxide content in soil within a narrow redox potential interval +190-(+240) mV with maximum at about +200 mV. The redox potential about +200 mV is the limit value between the production of nitrous oxide and its consumption.