|Gale, William - IOWA STATE UNIVERSITY|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 1995
Publication Date: N/A
Technical Abstract: No-till agricultural management has the potential to increase soil organic C, but little is known about the relative contribution of shoot and root C to soil organic C accumulation. Particulate organic matter (POM) is the first intermediate pool along the decay continuum between plant residue and soil humus. We devised a reciprocal transplant experiment to trace movement of surface-placed 14C-labelled shoot material and 14C-labelled roots into POM, whole soil and respired CO2 fractions. After 6 months, nearly all of the 14C loss from shoots could be accounted for by respired 14CO2 and negligible amounts were found in POM and soil fractions. In contrast, for the labelled root treatment, 14C in POM increased by over 400% and whole-soil 14C increased by a factor of 2. These data support the hypothesis that POM-C is derived primarily from roots and that significant amounts of C from shoot residue are lost as CO2 when aboveground crop residue remains on the soil surface.