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| Titel |
Nitrous oxide emissions from temperate grassland soils as affected by seasonal dairy soiled water application and soil type |
| VerfasserIn |
Paul Murphy, Denis Minogue, Padraig French, Dejun Li, Thomas Bolger |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250055165
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| Zusammenfassung |
| Nitrous oxide is a potent greenhouse gas (GHG) emitted to the atmosphere during
nitrification and denitrification, particularly following application of N to soil as fertiliser.
Approximately a third of Ireland’s GHG emissions are from the agricultural sector (very
high, by European standards) and N2O emissions from soils account for about
half of this. Therefore, decreasing N2O emissions from fertiliser N applied to soils
is important to decrease Ireland’s overall GHG emissions. One of the forms of
organic fertiliser N widely applied is dairy soiled water (DSW). This dilute effluent is
produced on dairy farms through washing down the milking parlour and holding areas
and contains significant quantities of N. It is typically applied to grassland soils.
The seasonal effect of DSW application on N2O emissions was examined using
intact soil monolith lysimeters (30 cm diameter, 70 cm depth) with two contrasting
grassland soils; a well-drained sandy loam acid brown earth (Cambisol), and a poorly
drained silt loam gley (Gleysol). N2O emissions were measured using the closed
chamber technique, sampling on 63 occasions over the year of the experiment.
All lysimeters were managed agronomically at 198 kg N ha-1 yr-1. There were 4
treatments; N applied as calcium ammonium nitrate (CAN) fertiliser only (FN), and three
treatments in which DSW was substituted for CAN at an equivalent total N rate during
May-August (T1), September-December (T2) and January-April (T3). DSW was
applied at the legal maximum rate of 50,000 l ha-1 every six weeks during the
application period. Fresh DSW was sampled, analysed and prepared for application by
dilution to give a total nitrogen (TN) content of 660 mg l-1 and an application rate of
33 kg N ha-1. Substituting DSW for CAN during the grass growing season (T1
and T3) significantly decreased total annual N2O emissions (3.97 and 3.89 kg N
ha-1yr-1, respectively) when compared to FN (6.36 kg N ha-1 yr-1). In contrast, annual
emissions when DSW was applied during the winter (T2) were not significantly
different from FN. Emissions tended to peak at approximately 0.02 to 0.03 kg N
ha-1day-1 within 5 days of DSW application and then decrease again to background
levels by day 21. During the winter however, these emissions tended to remain high
for longer. Mean daily losses for May-Aug and Jan-Apr DSW applications were
0.009 and 0.015 kg N ha-1day-1, respectively, but these increased to 0.021 for
Sep-Dec applications. Surprisingly, no significant difference was found between
N2O emissions from the two soils, despite the contrast in soil type and drainage
conditions. The lack of a significant difference may be due to heterogeneity in the poorly
drained gleysol; mean emissions from the gleysol were higher, but were also highly
variable. The mean emission factor (EF) recorded for DSW in this study (1.71 |
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