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

This Article Abstract 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 Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Smucker, A. J.M. Articles by Horn, R. Search for Related Content PubMed Articles by Smucker, A. J.M. Articles by Horn, R. GeoRef GeoRef Citation Agricola Articles by Smucker, A. J.M. Articles by Horn, R. Related Collections Structure and Properties Biogeochemical Processes Diffusion

Soil Micropore Development and Contributions to Soluble Carbon Transport within Macroaggregates

^a Michigan State University, Crop and Soil Sciences, 530 Plant & Soil Sci. Bldg., East Lansing, MI 48824-1325
^b 179 Pajang-Dong, Jangan-Gu, Suwon, Gyeonggi-Do, Korea 440-290
^c Inst. de Ingenieria Agraria y Suelos, Univ. Austral de Chile, Casilla 567, Valdivian, Chile
^d Inst. of Soil Science and Plant Nutrition, Olhausenstr 40, Christian Albrecht University, Kiel, 24118, Germany

View larger version (22K): [in this window] [in a new window]   FIG. 1. Projected possibilities for augmenting C sequestration in soils through a greater understanding of biogeochemical mechanisms within micropores of soil aggregates that could be realized in management operations. Greater knowledge of the relationships among flux rates, surface adsorption, hysteretic water capacities, pore blockage, and the bioavailability of organic compounds provide additional long-term soil C sequestration potentials within structured soils. These projected 150 and 200% increases could be realized with augmented biomass resources for increased soil organic matter accompanied by more stable soil aggregates containing greater microporosities that sequester higher quantities of C protected from microbial mineralization.

View larger version (34K): [in this window] [in a new window]   FIG. 2. This outline of the sources and pathways of soluble organic C (SOC) flowing among interaggregate macropores depicts pathways for SOC diffusion into myriads of newly formed intra-aggregate micropore networks produced by frequent drying and wetting cycles. Many of these new micropores are dead-end pores that store additional immobile water, as defined by DeSmedt and Wierenga (1979), within aggregate centers. A continuous flux of SOC into these newly exposed mineral surfaces contributes to the further stabilization of aggregates and appears to protect C from microbial mineralization (Park and Smucker, 2007).

View larger version (40K): [in this window] [in a new window]   FIG. 3. HYDRUS 2D models of water flow: (A) uniform water flow through homogeneous aggregates with similar interior regions, (B) water flow limited to exterior layers due to heterogeneous regions within aggregate interiors. To model the water movement inside the aggregates, the van Genuchten parameters were defined for each aggregate layer (Table 1). The values of f were used to define S. The parameters R, , and n were taken from Rosetta v. 1.0 (1999). To compare the water movement in different aggregate configurations, the water flow was modeled with the same and different texture distributions, implying different values for the van Genuchten parameters and Ks. A constant hydraulic gradient of 50 hPa was applied across the soil aggregate to generate the water flow (left to right).

View larger version (13K): [in this window] [in a new window]   FIG. 4. (a) Carbon mineralization rates by whole and interior regions of aggregates 4.0 to 6.3 mm in diameter, from a Hoytville clay loam soil managed as conventionally tilled (CT) and no-till (NT). (b) Differential ratios of C mineralization rates between interior and whole aggregates. Bars are the standard errors of three field replicates, n = 45.

View larger version (124K): [in this window] [in a new window]   FIG. 5. Synchrotron microtomographic image processed by Linux Red Hat software from Lindquist (2002). Blue and green colors indicate larger diameter macropores (>100 µm). These are connected to surrounding smaller fragmented and highly interconnected micropores. Red and yellow indicates diameters ranging between 8 and 100 µm (Peth et al., 2007).