Tuesday, 8 November 2005
8

Effects of Drying and Rewetting on CO2 and N2O Losses from Compacted and Uncompacted Soil.

Michael Beare1, Edward Gregorich2, Patrick St-George2, and Ulrica McKim2. (1) New Zealand Institute for Crop & Food Research, Gerald Street, Lincoln, Private Bag 4704, Christchurch, New Zealand, (2) Agriculture & Agri-Food Canada, 960 Carling Ave, Central Experimental Farm, Ottawa, ON K1A0C6, Canada

Soil compaction is likely to influence the chemical and biological response of soil to drying and rewetting. Soil samples were collected from a field trial investigating the effects of wheel traffic compaction on soil physical properties, N availability and greenhouse gas emissions. Intact soil cores were incubated at field capacity soil moisture (5 d), then dried gradually (3 d), before rapid rewetting to field capacity and continuously incubating the soils for a further 10 d. Fluxes of CO2 and N2O increased markedly following rewetting of dry soil. The CO2 flux following rewetting of uncompacted soil (1.0 g/cm3) was about 8 times greater than that of compacted (1.5 g/cm3) soil. In contrast the N2O flux following rewetting was about 10 times greater from compacted than uncompacted soil. The higher CO2 and N2O fluxes corresponded with higher levels of DOC and mineral N in uncompacted and compacted soils, respectively.

Handout (.pdf format, 129.0 kb)

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