Abstract:
Nitrous oxide (N
2
O) has significant impact on global warming and lea
ds to the depletion
of ozone in the stratosphere. Agricultural soil is
regarded as a major source of N
2
O
emissions. In recent years, greenhouse grown vegeta
bles have rapidly developed in China.
Although excessive fertilizer application in greenh
ouse vegetable production can result in
increased N
2
O emissions, research data on such emissions from g
reenhouse vegetables,
such as cucumber, remains limited. In this study, f
our nitrogen (N) fertilizer treatments
including 1,200 (N
1200
, traditional N amount), 900 (N
900
), and 600 kg N ha
-1
(N
600
) and the
control (N
0
) were carried out on cucumber in a greenhouse in t
he North China Plain.
Results showed that N
2
O emissions mainly occurred in the first five days
after
topdressing, and accounted for 75.8%
-95.2% of total N
2
O emissions produced in the
whole interval (10 days). Significant exponential c
orrelations were observed between N
2
O
flux and nitrification or denitrification rates (
P
< 0.01). The results also indicated that
nitrification dominated and played a more important
role in N
2
O emissions than
denitrification under the irrigation conditions of
the study (water-filled pore space
was
40.0 to 66.6%). Cumulative N
2
O emissions were 0.48-5.01 kg N ha
-1
in the cucumber
growing season, accounting for 0.28-0.38% of nitrog
en input. Compared to N
1200
,
treatment N
600
significantly reduced the rate of N
2
O emissions by 53.4%, and also
maintained cucumber yield. Based on this study, 50%
of the traditional N fertilizer rate
(N
600
) was considered sustainable for greenhouse cucumbe
r production in the North
China Plain.
Keywords:
Cucumber, Environmental factor, Nitrogen fertilizer
, N
2
O flux. Soil NO3
-
N.
