Submitted to: World Congress of Soil Science
Publication Type: Abstract Only
Publication Acceptance Date: 5/30/2001
Publication Date: 8/14/2002
Citation: Morris, D.R., Snyder, G.H. 2002. Microbial induced respiration in soils using 14c labelled substrate. 17th World Congress of Soil Science Abstracts. Vo. 1, page 396.
Technical Abstract: Studies involved in measuring microbial induced respiration in soils using a 14C labelled substrate have been used to provide estimates of soil organic matter oxidation potential. Two laboratory experiments were conducted to determine how enzyme saturating conditions correspond to non saturating conditions. Labelled 14C carboxy benzoate was appled to Florida Histosols and sandy soils at rates ranging from 32 to 8000 uM and incubated for 2 hrs. Soil enzyme substrate responses followed Michaelis Menton equations. In the both experiments, the Km of the Histosols were significantly different from the sandy soils indicating different microbial population. Vmax was different for each soil due to different quantities of enzyme present. Also, in both experiments, one of the sandy soils had activity that declined when Vmax was reached, which indicates that for some soils, applying substrate at enzyme saturating conditions and comparing microbial activities could lead to erroneous results. A correlation of ranks of the enzyme activities was performed on the samples in the second experiment. There was a strong relationship between the activity at the lowest substrate rate and the higher rates as indicated by significant correlation coefficients. Using less than enzyme saturated conditions should be adequate for estimating soil organic matter oxidation potential.