Interannual variation in nitrous oxide emissions from perennial ryegrass/white clover grassland used for dairy production.
Nitrous oxide (N2 O) emissions are subject to intra- and interannual variation due to changes in weather and management. This creates significant uncertainties when quantifying estimates of annual N2 O emissions from grazed grasslands. Despite these uncertainties, the majority of studies are short-term in nature (<1 year) and as a consequence, there is a lack of data on interannual variation in N2 O emissions. The objectives of this study were to (i) quantify annual N2 O emissions and (ii) assess the causes of interannual variation in emissions from grazed perennial ryegrass/white clover grassland. Nitrous oxide emissions were measured from fertilized and grazed perennial ryegrass/white clover grassland (WC) and from perennial ryegrass plots that were not grazed and did not receive N input (GB), over 4 years from 2008 to 2012 in Ireland (52°51'N, 08°21'W). The annual N2 O-N emissions (kg ha(-1); mean ± SE) ranged from 4.4 ± 0.2 to 34.4 ± 5.5 from WC and from 1.7 ± 0.8 to 6.3 ± 1.2 from GB. Interannual variation in N2 O emissions was attributed to differences in annual rainfall, monthly (December) soil temperatures and variation in N input. Such substantial interannual variation in N2 O emissions highlights the need for long-term studies of emissions from managed pastoral systems.
Animal & Grassland Research and Innovation Centre, Teagasc, Moorepark, Fermoy, Co. Cork, Ireland; Department of Botany, School of Natural Sciences, Trinity College Dublin, College Green, Dublin 2, Ireland.
William
W
Burchill
Dejun
D
Li
Gary J
GJ
Lanigan
Micheal
M
Williams
James
J
Humphreys
D000393:Air Pollutants / Q000032:analysis*; D002980:Climate; D003612:Dairying; D005308:Fertilizers; D065948:Grassland; D007494:Ireland; D008129:Lolium / Q000378:metabolism*; D009609:Nitrous Oxide / Q000032:analysis*; D029921:Trifolium / Q000378:metabolism*
D000393:Air Pollutants; D005308:Fertilizers; D009609:Nitrous Oxide
freeze-thaw cycles; grazing; interannual variation; nitrous oxide; rainfall; regulating factors; white clover grassland