Emission of N"2O, N"2 and CO"2 from soil fertilized with nitrate: effect of compaction, soil moisture and rewetting [An article from: Soil Biology and Biochemistry]

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Description:
Soil compaction and soil moisture are important factors influencing denitrification and N"2O emission from fertilized soils. We analyzed the combined effects of these factors on the emission of N"2O, N"2 and CO"2 from undisturbed soil cores fertilized with N15O"3^- (150kg Nha^-^1) in a laboratory experiment. The soil cores were collected from differently compacted areas in a potato field, i.e. the ridges (@r"D=1.03gcm^-^3), the interrow area (@r"D=1.24gcm^-^3), and the tractor compacted interrow area (@r"D=1.64gcm^-^3), and adjusted to constant soil moisture levels between 40 and 98% water-filled pore space (WFPS). High N"2O emissions were a result of denitrification and occurred at a WFPS>=70% in all compaction treatments. N"2 production occurred only at the highest soil moisture level (>=90% WFPS) but it was considerably smaller than the N"2O-N emission in most cases. There was no soil moisture effect on CO"2 emission from the differently compacted soils with the exception of the highest soil moisture level (98% WFPS) of the tractor-compacted soil in which soil respiration was significantly reduced. The maximum N"2O emission rates from all treatments occurred after rewetting of dry soil. This rewetting effect increased with the amount of water added. The results show the importance of increased carbon availability and associated respiratory O"2 consumption induced by soil drying and rewetting for the emissions of N"2O.