Nitrogen Mineralization and Denitrification in Organic Soils

The quantities of N mineralized when columns of Histosols were incubated at field capacity for periods up to 28 days corresponded to 500‐600 kg N/ha per year without correction for N lost by denitrification. An absorption train utilizing molecular sieve 5Å to collect N 2 O was used in denitrification experiments. Under an argon stream, 52‐53% of the added NO 3 ‐ ‐N was recovered as N 2 O, whereas the maximum concentration of N 2 O accumulating in the headspace of closed vessels amounted to 65% of the added NO 3 ‐ ‐N. The quantity of N 2 O either collected or accumulating in a headspace was reduced to 15‐41% of the NO 3 ‐ ‐N denitrified when a second addition of NO 3 ‐ was made to the soils. Denitrification occurred in both drained and flooded soil columns amended with NO 3 ‐ . The N 2 O recovered ranged from 2.5‐9% and 9‐19% of the NO 3 ‐ ‐N denitrified in the drained and flooded columns, respectively. From 78‐98% of the N 2 O was recovered in leachate from the flooded columns and the corresponding range for the drained columns was 11‐52%.