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Title: ROOT-DERIVED C AND THE FORMATION AND STABILIZATION OF AGGREGATES

Author
item GALE, WILLIAM - IOWA STATE UNIVERSITY
item Cambardella, Cynthia

Submitted to: Ecological Society of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/6/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Prudent land-management practices have the potential to increase soil organic C and enhance soil structural stability. We devised an experiment to examine changes in free- and aggregate-associated OM during in situ decomposition of **14C labeled roots. We sampled the experiment on day 0, 90, 180, 270, and 360 and isolated aggregate size fractions in order to quantify and characterize the material released from aggregates with slaking. We used densiometric separations to isolate free- and intraaggregate POM. On day 0 and day 90, substantial amounts of previously occluded POM were released with slaking. By day 180, most of the **14C lost from macroaggregates due to slaking was associated with intact microaggregates, and no **14C was released into the free POM pool. There was a significant linear increase with time in the amount of new, root-derived C associated with microaggregates released from macroaggregates with slaking. These results support the hypothesis that new microaggregates were being formed within existing macroaggregates and provide strong evidence that in no-till, aggregate formation and stabilization processes are directly related to the decomposition of root-residue and the dynamics of POM C in soil.