November 15, 2006
Journal Article

Nitrogen Mineralization and Assimilation at Millimeter Scales

Abstract

This study used inoculated, artificial soil microcosms containing sand, clay, cellulose, and localized hotspots of highly labile, organic-N containing dead bacteria to study N mineralization and assimilation at submillimeter and centimeter scales. Labeling with 15NH4+ along with measurement of label assimilated into microbial biomass at the bulk scale allowed estimation of gross rates of ammonification and N assimilation using isotope dilution. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) analyses of transects of organic-15N across Si wafers in contact with the microcosms indicated strong gradients of 15NH4+ assimilation as a function of proximity to the hotspots that were not apparent using bulk analyses. This combination of bulk and ToF-SIMS analyses represents a powerful approach to explore the physical and biochemical factors that affect N process heterogeneities in soils.

Revised: January 24, 2007 | Published: November 15, 2006

Citation

Cliff J.B., P.J. Bottomley, D.J. Gaspar, and D.D. Myrold. 2006. "Nitrogen Mineralization and Assimilation at Millimeter Scales." Soil Biology and Biochemistry 39, no. 3:823–826. PNNL-SA-48741. doi:10.1016/j.soilbio.2006.10.005