Can intra-aggregate pore structures affect the aggregate's effectiveness in protecting carbon?
- MSU
Aggregates are known to provide physical protection to soil organic matter shielding it from rapid decomposition. Spatial arrangement and size distribution of intra-aggregate pores play an important role in this process. This study examined relationships between intra-aggregate pores measured using X-ray computed micro-tomography images and concentrations of total C in 4–6 mm macro-aggregates from two contrasting land use and management practices, namely, conventionally tilled and managed row crop agricultural system (CT) and native succession vegetation converted from tilled agricultural land in 1989 (NS). Previous analyses of these aggregates indicated that small (<15 μm) and large (>100 μm) pores prevail in NS aggregates while medium (30–90 μm) pores are more abundant in CT aggregates (Kravchenko et al., 2011; Wang et al., 2012). We hypothesized that these differences in pore size distributions affect the ability of macro-aggregates to protect C. The results of this study supported this hypothesis. Consistent with greater heterogeneity of pore distributions within NS aggregates we observed higher total C and greater intra-aggregate C variability in NS as compared with CT aggregates. Total C concentrations and intra-aggregate C standard deviations were negatively correlated with fractions of medium sized pores, indicating that presence of such pores was associated with lower but more homogeneously distributed total C. While total C was positively correlated with presence of small and large pores. The results suggest that because of their pore structure NS macro-aggregates provide more effective physical protection to C than CT aggregates.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- NSFOTHERDOE - BASIC ENERGY SCIENCES
- OSTI ID:
- 1063006
- Journal Information:
- Soil Biology and Biochemistry, Vol. 57; ISSN 0038-0717
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
Protection of organic carbon in soil microaggregates occurs via restructuring of aggregate porosity and filling of pores with accumulating organic matter.
STOCK AND DISTRIBUTION OF TOTAL AND CORN-DERIVED SOIL ORGANIC CARBON IN AGGREGATE AND PRIMARY PARTICLE FRACTIONS FOR DIFFERENT LAND USE AND SOIL MANAGEMENT PRACTICES