Nitrification Inhibitor Reduces Nitrous Oxide Production from Different Soil Profiles of an Andosol Soil

Abstract

A laboratory incubation was conducted to evaluate nitrous oxide (N₂O) production during nitrification and the effect of a nitrification inhibitor on N₂O production from different profiles in a Japanese orchard Andosol. Soils were collected from five profiles: A1, A2, Bw1, Bw2, and BC. The soils were treated with ammonium sulfate at the rate of 200 mg N kg⁻¹ with or without dicyandiamide (DCD) and incubated under aerobic conditions for 32 days. The net nitrification rate without DCD during the first 8 days was greater in the surface soils than in the subsurface soils. Accordingly, the surface soils showed a greater cumulative N₂O production than the subsurface soils. Application of DCD significantly reduced the nitrification rate and thus N₂O production from any depths of soils by 33.8 to 62.9%. Our study showed that substantial N₂O was produced from the subsurface soil, although the amount was less than from the surface soils.

Keywords:

• Dicyandiamide
• net nitrification rate
• nitrous oxide
• orchard soil
• soil depth