『Abstract
Field management is expected to influence nitrous oxide (N2O) production from arable cropping systems through
effects on soil physics and biology. Measurements of N2O
flux were carried out on a weekly basis from April 2008 to August
2009 for a spring sown barley crop at Oak Park Research Centre,
Carlow, Ireland. The soil was a free draining sandy loam typical
of the majority of cereal growing land in Ireland. The aims of
this study were to investigate the suitability of combining reduced
tillage and a mustard cover crop (RT-CC) to mitigate nitrous oxide
emissions from arable soils and to validate the DeNitrification-DeComposition
(DNDC) model version (v. 9.2) for estimating N2O
emissions. In addition, the model was used to simulate N2O emissions for two sets of future climate scenarios
(period 2021-2060). Field results showed that although the daily
emissions were significantly higher for RT-CC on two occasions
(p＜0.05), no significant effect (p＞0.05) on the cumulative N2O flux, compared with the CT treatment, was found.
DNDC was validated using N2O data collected
from this study in combination with previously collected data
and shown to be suitable for estimating N2O
emissions (r2=0.70), water-filled pore space (WFPS)
(r2=0.58) and soil temperature (r2=0.87)
from this field. The relative deviations of the simulated to the
measured N2O values with the 140 kg N ha-1
fertiliser application rate were -36％ for RT-CC and -19％ for CT.
Root mean square error values were 0.014 and 0.007 kg N2O-N
ha-1 day-1, respectively, indicating a reasonable
fit. Future cumulative N2O fluxes and total
denitrification were predicted to increase under the RT-CC management
for all future climate projections, whilst predictions were inconsistent
under the CT. Our study suggests that the use of RT-CC as an alternative
farm management system for spring barley, if the sole objective
is to reduce N2O emissions, may not be successful.
Keywords: Cover crop; Reduced tillage; Nitrous oxide; Arable soils;
DNDC model; Future climate』
1. Introduction
2. Materials and methods
2.1. Field experimental site
2.2. Experimental design and management
2.3. Field N2O fluxes
2.4. Soil nitrate concentration, WFPS and soil temperature
2.5. DNDC validation
2.6. Climate change scenarios
2.7. Statistical analysis
3. Results
3.1. Assessing the effects of RT-CC on N2O
present-day emissions and validating the DNDC model
3.2. Assessing the effect of RT-CC management on future N2O emissions
4. Discussion
4.1. Assessing the effects of RT-CC on present-day N2O emissions and validating the DNDC model
4.2. Assessing the effects of RT-CC management on future N2O emissions
5. Conclusions
Acknowledgements
References