Z. Cai et al., Nitrous oxide and dinitrogen emissions from soil under different water regimes and straw amendment, CHEMOSPHERE, 42(2), 2001, pp. 113-121
In a laboratory study, soil amended with and without wheat straw (2.8 g kg(
-1) soil) was incubated under 70% water holding capacity (WHC), continuousl
y flooded and flooded/drained cycle conditions at 30 degrees C for 51 days.
Dinitrogen and N2O evolution and ammonia volatilisation were measured duri
ng the incubation. Extractable NH4+-N and NO3--N were determined at the end
of the incubation. Entrapped N-2, N2O, and dissolved NH4+-N and NO3--N in
drainage water were measured in the flooded/drained cycle treatment when th
e floodwater was drained. The results indicated that N loss through ammonia
volatilisation was undetected in all treatments due to the low soil pH val
ue (pH(H2O) = 5.87) and no air movement. The recovery of urea-N-15 as N-2 w
as lowest in the continuously flooded treatments (0.75% and 0.96% with and
without straw amendment, respectively), highest in the 70% WHC treatments (
5.65% and 4.41%, respectively), and intermediate in the flooded/drained cyc
le treatments (1.79% and 2.65%, respectively). The recovery of urea-N-15 as
N2O was in the same order as that of N-2, negligible in the continuously f
looded treatments, 0.01% and 0.07% in the flooded/drained cycle treatments,
and 1.29% and 2.23% in the 70% WHC treatments, respectively. Peak N2O evol
ution rates were observed after the floodwater was drained but no substanti
al evolution was found after the soil was reflooded following drained perio
ds. However, peak N-2 evolution rates were observed after the onset of both
drainage and re-flooding. Considerable quantities of N-2 but no detectable
N2O were entrapped in the flooded soil. (C) 2000 Elsevier Science Ltd. All
rights reserved.