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United States Department of Agriculture

Agricultural Research Service

Title: Above and Belowground-Derived C in Stable and Unstable Aggregates

Authors
item Gale, William - IOWA STATE UNIVERSITY
item Cambardella, Cynthia

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: October 22, 1998
Publication Date: N/A

Technical Abstract: Soil structural stability is correlated with amount of particulate organic matter (POM) C present in soil. Our experimental objective was to quantify new C inputs from above- and belowground plant litter into stable and unstable soil macroaggregates. We devised an experiment to examine changes in aggregate-associated POM C during in situ decomposition of **14C labeled droots or shoots. The experiment was destructively sampled every 3 months for one year. We assumed that only stable macroaggregates survived slaking. All macroaggregates (>250-um) contained more root-derived POM C than surface-residue-derived POM C. Stable small macroaggregates (250- to 2000-um) had higher concentrations of new root-derived POM C than unstable small macroaggregates. In contrast, the concentration of new surface-residue-derived POM C was the same for stable and unstable small macroaggregates. Our results suggest that new root-derived C inputs are more important for determining macroaggregate stability in our simulated no-till system than new surface-residue-derived C inputs.

Last Modified: 10/1/2014