Denitrification, organic matter and redox potential transformations in Cambisols
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Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, P.O. Box 201, 20-290 Lublin 27, Poland
Catholic University of Lublin, Kraśnicka 102, 20-718 Lublin, Poland
Int. Agrophys. 2003, 17(4): 219–227
Two greenhouse gases: N2O and CO2 as well as Corg and redox potential transformation were investigated. Fourteen Cambisols (0-10 cm) developed from sand, silt, loess, loam and clay characteristic for Poland were incubated under flood conditions in closed flasks at 20°C temperature for 7 days. According to denitrification activity the soils were divided into two groups - of lower (I) and higher (II) activity. Production of nitrous oxide lasting 3-5 days was followed by its absorption in the case of three soils out of fourteen. The total N2O amount reached from 3-91% of the initial nitrate - N content and was positively correlated with the Corg content. Diurnal N2O production was positively correlated with Corg and diurnal CO2 emission. The N2O absorption rate for the three soils was 0.16 mg N2O-N kg-1day-1, 20.6 mg N2O-N kg-1day-1 and 3.3 mg N2O-N kg-1day-1 in sandy, loamy and in the clay soil, respectively. The diurnal fluxes of carbon dioxide ranged from 1.24 to 9.96 mg of CO2-C kg-1 d-1 and from 26.8 to 144 mg of CO2-C kg-1 for I and II group, respectively. Diurnal carbon dioxide production showed a high positive correlation with Corg. The soils investigated were characterised by a very wide range of redox potential measured for the maximal cumulative N2O emission from +417 to +233 mV. The beginning of N2O emission from the light textured soils was observed above 400 mV while from the heavier textured soil below 400 mV. N2O emis- sion was correlated with soil redox potential.