Soil Compaction and Fertilization Effects on Nitrous Oxide and Methane Fluxes in Potato Fields

Abstract This study was conducted to determine the effect of soil compaction and N fertilization on the fluxes of N 2 O and CH 4 in a soil (fine‐silty Dystric Eutrochrept) planted with potato ( Solanum tuberosum L.). Fluxes of N 2 O and CH 4 were measured weekly for 1 yr on two differently fertilized (50 and 150 kg N ha ‐1 ) fields. For the potato cropping period (May–September) these fluxes were quantified separately for the ridges (soil bulk density ρ b = 1.05 Mg m ‐3 ) covering two‐thirds of the total field area, and for the uncompacted (ρ b = 1.26 Mg m ‐3 ) and the tractor‐traffic‐compacted (ρ b = 1.56 Mg m ‐3 ) interrow soils, each of which made up one‐sixth of the field area. The annual N 2 O‐N emissions for the low and the high rates of N fertilization were 8 and 16 kg ha ‐1 , respectively. The major part (68%) of the total N 2 O release from the fields during the cropping period was emitted from the compacted tractor tramlines; emissions from the ridges made up only 23%. The annual CH 4 ‐C uptake was 140 and 118 g ha ‐1 for the low and high levels of fertilization, respectively. The ridge soil and the uncompacted interrow had mean CH 4 ‐C oxidation rates of 3.8 and 0.8 µg m ‐2 h ‐1 , respectively; however, the tractor‐compacted soil released CH 4 at 2.1 µg CH 4 ‐C m ‐2 h ‐1 . The results indicate thas soil compaction was probably the main reason for increased N 2 O emission and reduced CH 4 uptake of potato‐cropped fields.