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Title: PARTICULATE ORGANIC MATTER IN STABLE AND UNSTABLE AGGREGATES

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

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/8/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: An important goal of soil management is to maintain high soil structural stability. It is known that roots and fungal hyphae contribute to the formation of soil aggregates. However, little is understood about how the decomposition of these organic binding agents affects aggregate stability. It is hypothesized that as roots and hyphae begin to decompose they enter into an intermediate pool in the decay continuum between plant residue and humus known as particulate organic matter (POM). The purpose of our study is to: 1) determine the amount of POM-C in stable and unstable aggregates, and 2) measure changes in intra-aggregate POM-C concentration and aggregate stability during a 6-month incubation period. We used two wetting treatments to isolate size classes containing aggregates with different relative stability. Samples that were wet prior to sieving contained aggregates that were less stable relative to the corresponding size class in the slaked treatment. The use of 14-C labeled roots allowed us to trace the movement of C into the POM-C pool. Preliminary results indicate that POM-C is more than twice as high in macroaggregates.