Dehydrogenase activity, redox potential, and emissions of carbon dioxide and nitrous oxide from Cambisols under flooding conditions

Abstract

Samples from topsoils (0–10 cm) of 16 Polish arable Cambisols developed from different parent materials (sand, silt, sandy gravel, loess, loam and clay), were incubated under flooded conditions with NO3 –. Dehydrogenase activity, redox potential (Eh), and emissions of CO2 and N2O were measured. According to dehydrogenase activity, the soils were divided into two groups: those of low activity (I), where the final dehydrogenase activity was 0.03 nmol TPF g–1 min–1. Generation of CO2 and of N2O under flooded conditions was shown to be significantly related to dehydrogenase activity. Soil dehydrogenase activity increased curvilinearly with organic matter content, showed a maximum at pH 7.1, and decreased curvilinearly with Eh. The final cumulative CO2 production increased linearly with soil organic matter content and curvilinearly with dehydrogenase activity and decreased linearly with Eh. The most significant relationship was found with dehydrogenase activity (R 2=0.74, P<0.001). The final cumulative N2O production decreased linearly with Eh and increased curvilinearly with pH and dehydrogenase activity but linearly with organic matter content; the most significant relation being found with dehydrogenase activity (R 2=0.69, P<0.001). The CO2:N2O ratio in the gases evolved increased curvilinearly with Eh and decreased with dehydrogenase activity and N2O and CO2 production.