ARS | Publication request: Analysis of the respiratory response of soil microbial biomass to different substrates

Submitted to: Soil Ecology Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: February 10, 2007
Publication Date: N/A

Technical Abstract: The criticism of the microbial biomass analysis using respiratory response to glucose has centered on the fact that only glucose sensitive organisms will respond. Thus only glucose utilizing organisms will contribute to the respiration response. In addition, all of the respiration response does not come from glucose but also from microorganism endogenous respiration. We have used a series of 14C labeled compounds to investigate the specific respiration response of different soils. Higher organic matter soils utilized compounds like urea and oxalate to a greater extent than glucose. Sandy soils responded to glucose and arginine more that the other substrates. Two agricultural soils were fairly uniform in substrate use. The amount of endogenous metabolism varied between soils but may be useful in characterizing the soil microbial community when studying soils from different ecosystems. The analysis of the long-term use of substrates showed that substrates used more rapidly in the early stages of decomposition had higher concentrations (more remaining) than substrates that initially decomposed slowly. This relationship will influence long-term soil C sequestration.