Abstract: A laboratory incubation experiment was conducted to investigate
nitrous oxide (N_2O) emission and reduction in a paddy
soil (Stagnic Anthrosol) response to the pretreatment of water regime. The paddy
soil was maintained under either air-dried (sample D) or submerged (sample F)
conditions for 110 d before the soil was adjusted into soil moisture of 20%,
40%, 60%, 80% and 100% water holding capacity (WHC) respectively, and then
incubated with or without 10%(v/v) acetylene for 138 h at 25°C. At lower
soil water content (⩽ 60% WHC), N_2O emission from the
sample F was 2.29 times higher than that from the sample D (P < 0.01).
While, N_2O emission from the sample F was only 29 and 14
percent of that from the sample D at the soil moisture of 80% and 100% WHC,
respectively (P < 0.01). The maximal N_2O emissions
observed at soil moisture of 80% WHC were about 24 and 186 times higher than
the minima obtained at the soil moisture of 20% WHC for the sample F and D,
respectively. But at the soil moisture of 80% and 100% WHC,
N_2O emission from the sample F with acetylene(F+ACE) was
comparable to that of the sample D with acetylene (D+ACE). The results showed
that the F sample produced N_2O ability in denitrification
was similar to the sample D, however, the sample F was in the better reduction
of N_2O to N_2 than the sample D even
after the soil moisture was adjusted into the same level of 80% or 100% WHC.
Therefore, the pretreatment of water regime influenced the strength and product
composition of denitrification and N_2O emission from the
paddy soil.
