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Nitrous oxide emissions from a legume pasture and the influences of liming and urine addition
Nitrous oxide (N 2O) is a potent greenhouse gas contributing to global radiative forcing. Grazed legume pasture is one of the major agricultural land uses in southern Australia and no N 2O emission studies have been undertaken previously on this system. A study over 1 year has been undertaken measur...
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Published in: | Agriculture, ecosystems & environment ecosystems & environment, 2010-03, Vol.136 (3), p.262-272 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that cite this one |
Online Access: | Get full text |
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Summary: | Nitrous oxide (N
2O) is a potent greenhouse gas contributing to global radiative forcing. Grazed legume pasture is one of the major agricultural land uses in southern Australia and no N
2O emission studies have been undertaken previously on this system. A study over 1 year has been undertaken measuring N
2O emissions from legume pasture at Wagga Wagga, Australia. The study was embedded within a larger on-farm study of the management of acid soils. Sampling involved simultaneous N
2O emission measurements on two paddocks each of: acidic soil with pH 4.0; limed soil with soil pH 5.5, and limed soil with addition of 20
g
N
m
−2 of animal urine. The average emission of N
2O from the acidic legume pasture was 0.35
kg
N
ha
−1
y
−1 with a standard error of 0.03
kg
N
ha
−1
y
−1. Isotope measurements indicated that in aerobic conditions the ratio of N
2O emissions to gross mineralisation was 0.01–0.05%. Liming did not make a significant change to the average N
2O emissions. The average of daily N
2O emissions are: for the acidic plots 0.96
±
0.07
mg
N
m
−2
d
−1 and for the limed plots 0.88
±
0.04
mg
N
m
−2
d
−1. We conclude that under the conditions experienced at Wagga Wagga, which are typical of many Australian pastures, liming does not change the N
2O emissions. Measurements from the urine-treated soil showed that between 0.1 and 0.2% of the nitrogen in the urine was released as N
2O. These and a compilation of other emission factors for N
2O emissions from urine addition to pasture give a median emission factor of 0.7%, significantly smaller than the two default values of 2% and 1% recommended by the Revised 1996 and the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. |
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ISSN: | 0167-8809 1873-2305 |
DOI: | 10.1016/j.agee.2009.10.013 |