Park, E.J. and A.J.M. Smucker
Presented at the All Scientist Meeting (2004-10-08 )
Changes in the stability of soil macro-aggregates and associated distributions of C, N and microorganisms within macro-aggregates are induced by multiple wetting/drying cycles. We identified pore expansion processes which promote C sequestration when stable pore structures develop and promote the influx of dissolved organic C within aggregates. Aggregates, 6.3-9.5mm across, from a long-term no tillage site of a Wooster silt loam were incubated for 35 days with no wetting/drying cycles and no glucose (Control), 5 wetting/drying cycles and no glucose (W/D), and 5 wetting/drying cycles and 250mg glucose-C/g soil (W/D+G). Aggregate stability decreased with W/D cycles but could be recovered with additions of glucose. It appears that larger quantities of C respired from exterior layers of aggregates than from interior regions and more glucose diffused into interior regions of aggregates by W/D cycles. Changes in spatial distributions of microorganisms and promoted porosities within aggregates are being analyzed for each treatment.
Back to meeting | Show |