HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Gaston, L.A. Articles by Locke, M.A. Search for Related Content PubMed PubMed Citation Articles by Gaston, L.A. Articles by Locke, M.A. Agricola Articles by Gaston, L.A. Articles by Locke, M.A. Related Collections Flow Fate Vadose Zone Processes and Chemical Transport

SHORT COMMUNICATIONS

Differences in Microbial Biomass, Organic Carbon, and Dye Sorption between Flow and No-Flow Regions of Unsaturated Soil

^a Dep. of Agronomy, 104 Sturgis Hall, LSU AgCenter, Baton Rouge, LA 70803
^b USDA-ARS Southern Weed Science Unit, P.O. Box 350, Stoneville, MS 38776

* Corresponding author (lgaston{at}agctr.lsu.edu)

Received for publication August 7, 2001. Transport models in which the liquid phase is partitioned between conducting and nonconducting regions allow the possibility that degradation and sorption are different in these regions. However, there is little information on biological or chemical differences between conducting and nonconducting regions of the soil matrix. Previous work by the authors on Br^- transport through unsaturated, intact soil cores of Dundee silty clay loam (fine-silty, mixed, active, thermic Typic Endoaqualf) indicated non-equilibrium conditions that could be well-described by a two-region model. Fitted parameters indicated little solute transfer between flow regions, suggesting that dye movement in unsaturated soil might delineate conducting and nonconducting regions of this soil. Steady-state, unsaturated flow was established in intact cores (10 by 30 cm) of the Dundee soil, then Br^- and erioglaucine dye were displaced through these cores. The soil cores were then sectioned into 5-cm segments and stained soil was separated from unstained soil. Microbial biomass C, organic C, and dye sorption K_D (= g_sorbed kg^-1_soil/g L^-1) values for stained and unstained soil were determined. Stained soil had higher microbial biomass C but generally lower organic C and lower affinity for dye sorption than unstained soil from the same depth increment. Fraction of immobile water, dispersion, and mass transfer between conducting and nonconducting regions were consistent with previous results.

Abbreviations: CT, conventional tillage • NT, no tillage