Abstract:

Laboratory experiments were conducted to examine the effect of charcoal addition on N₂O emissions resulting from rewetting of air-dried soil. Rewetting the soil at 73% and 83% of the water-filled pore space (WFPS) caused a N₂O emission peak 6 h after the rewetting, and the cumulative N₂O emissions throughout the 120-h incubation period were 11 ± 1 and 13 ± 1 mg N m⁻², respectively. However, rewetting at 64% WFPS did not cause detectable N₂O emissions (−0.016 ± 0.082 mg N m⁻²), suggesting a severe sensitivity to soil moisture. When the soils were rewetted at 73% and 78% WFPS, the addition of charcoal to soil at 10 wt% supressed the N₂O emissions by 89% . In contrast, the addition of the ash from the charcoal did not suppress the N₂O emissions from soil rewetted at 73% WFPS. The addition of charcoal also significantly stimulated the N₂O emissions from soil rewetted at 83% WFPS compared with the soil without charcoal addition (P < 0.01). Moreover, the addition of KCl and K₂SO₄ did not show a clear difference in the N₂O emission pattern, although Cl⁻ and , which were the major anions in the charcoal, had different effects on N₂O-reducing activity. These results indicate that the suppression of N₂O emissions by the addition of charcoal may not result in stimulation of the N₂O-reducing activity in the soil because of changes in soil chemical properties.

Keywords: denitrification; K fertilization; liming; N2O-reducing activity; rewetting effect

Document Type: Research article

DOI: 10.1111/j.1747-0765.2007.00123.x

Affiliations: 1: Graduate School of Bio-Applications and Systems Engineering and 2: Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan