Ammonia, Methane, and Nitrous Oxide Emission from Pig Slurry Applied to a Pasture in New Zealand
- Robert R. Sherlocka,
- Sven G. Sommer *b,
- Rehmat Z. Khanabcd,
- C. Wesley Woodb,
- Elizabeth A. Guertalb,
- John R. Freneyc,
- Christopher O. Dawsond and
- Keith C. Camerona
- a Soil Plant and Ecological Sciences Division, P.O. Box 84, Lincoln Univ., Canterbury, New Zealand
b Dep. of Agronomy and Soils, 236 Funchess Hall, Auburn University, AL 36849-5412
c CSIRO Plant Industry, G.P.O. Box 1600, Canberra, ACT, Australia
d Animal and Food Sciences Division, P.O. Box 84, Lincoln Univ., Canterbury, New Zealand
Much animal manure is being applied to small land areas close to animal confinements, resulting in environmental degradation. This paper reports a study on the emissions of ammonia (NH3), methane (CH4), and nitrous oxide (N2O) from a pasture during a 90-d period after pig slurry application (60 m3 ha−1) to the soil surface. The pig slurry contained 6.1 kg total N m−3, 4.2 kg of total ammoniacal nitrogen (TAN = NH3 + NH4) m−3, and 22.1 kg C m−3, and had a pH of 8.14. Ammonia was lost at a fast rate immediately after slurry application (4.7 kg N ha−1 h−1), when the pH and TAN concentration of the surface soil were high, but the loss rate declined quickly thereafter. Total NH3 losses from the treated pasture were 57 kg N ha−1 (22.5% of the TAN applied). Methane emission was highest (39.6 g C ha−1 h−1) immediately after application, as dissolved CH4 was released from the slurry. Emissions then continued at a low rate for approximately 7 d, presumably due to metabolism of volatile fatty acids in the anaerobic slurry–treated soil. The net CH4 emission was 1052 g C ha−1 (0.08% of the carbon applied). Nitrous oxide emission was low for the first 14 d after slurry application, then showed emission peaks of 7.5 g N ha−1 h−1 on Day 25 and 15.8 g N ha−1 h−1 on Day 67, and decline depending on rainfall and nitrate (NO3) concentrations. Emission finally reached background levels after approximately 90 d. Nitrous oxide emission was 7.6 kg N ha−1 (2.1% of the N applied). It is apparent that of the two major greenhouse gases measured in this study, N2O is by far the more important tropospheric pollutant.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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