N₂O and CO₂ emissions following clover and cellulose incorporation into a New Zealand pastoral soil
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Date
2010-08
Type
Conference Contribution - published
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Abstract
Clover (Trifolium repens L.) and clover + different proportions of cellulose were incorporated into soil and
the nitrous oxide (N₂O) and carbon dioxide (CO₂) emissions measured. Ground, dried clover shoots and
cellulose were mixed to carbon: nitrogen (C: N) ratios of ~9 (‘clover only’), 20, 30 and 40. Soil samples
were incubated at water–filled pore space (WFPS) of 86% and 20°C. Over 42 d, N₂O emissions from the
controls averaged 9 mg/kg soil (6 g total N/kg soil), indistinguishable from the ‘clover only’ (1.5 g N
incorporated/kg soil) and ‘C: N 20’ treatments. Corresponding N₂O emissions from the ‘C: N 30’ and ‘C: N
40’ treatments averaged nearly 50% greater (P <0.05) and these two treatment effects were indistinguishable.
Over 42 d, CO₂ emissions from the controls averaged 4 g/kg soil. There was a linear C (incorporation rate)
‘dose effect’ on CO₂ emissions (0.15 g CO₂/g C, R² = 0.80) with no difference between clover and clover +
cellulose. Over 145 d, CO₂ emissions from the controls averaged 17 g/kg soil and the C ‘dose effect’ was
0.38 g CO₂/g C (R² = 0.98). Incorporating different plant materials into soil affected the N₂O and CO₂
emissions differently.
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© 2010 19th World Congress of Soil Science, Soil Solutions for a Changing World. Archived with publisher permission.