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Caplan JS, Giménez D, Subroy V, Heck RJ, Prior SA, Runion GB, Torbert HA. Nitrogen-mediated effects of elevated CO 2 on intra-aggregate soil pore structure. GLOBAL CHANGE BIOLOGY 2017; 23:1585-1597. [PMID: 27726258 DOI: 10.1111/gcb.13496] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 08/24/2016] [Accepted: 09/01/2016] [Indexed: 05/14/2023]
Abstract
Soil pore structure has a strong influence on water retention, and is itself influenced by plant and microbial dynamics such as root proliferation and microbial exudation. Although increased nitrogen (N) availability and elevated atmospheric CO2 concentrations (eCO2 ) often have interacting effects on root and microbial dynamics, it is unclear whether these biotic effects can translate into altered soil pore structure and water retention. This study was based on a long-term experiment (7 yr at the time of sampling) in which a C4 pasture grass (Paspalum notatum) was grown on a sandy loam soil while provided factorial additions of N and CO2 . Through an analysis of soil aggregate fractal properties supported by 3D microtomographic imagery, we found that N fertilization induced an increase in intra-aggregate porosity and a simultaneous shift toward greater accumulation of pore space in larger aggregates. These effects were enhanced by eCO2 and yielded an increase in water retention at pressure potentials near the wilting point of plants. However, eCO2 alone induced changes in the opposite direction, with larger aggregates containing less pore space than under control conditions, and water retention decreasing accordingly. Results on biotic factors further suggested that organic matter gains or losses induced the observed structural changes. Based on our results, we postulate that the pore structure of many mineral soils could undergo N-dependent changes as atmospheric CO2 concentrations rise, having global-scale implications for water balance, carbon storage, and related rhizosphere functions.
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Affiliation(s)
- Joshua S Caplan
- Department of Environmental Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, New Jersey, 19010, USA
| | - Daniel Giménez
- Department of Environmental Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, New Jersey, 19010, USA
| | - Vandana Subroy
- Department of Environmental Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, New Jersey, 19010, USA
| | - Richard J Heck
- School of Environmental Sciences, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada
| | - Stephen A Prior
- US Department of Agriculture, Agricultural Research Service, National Soil Dynamics Laboratory, 411 South Donahue Drive, Auburn, Alabama, 36832, USA
| | - G Brett Runion
- US Department of Agriculture, Agricultural Research Service, National Soil Dynamics Laboratory, 411 South Donahue Drive, Auburn, Alabama, 36832, USA
| | - H Allen Torbert
- US Department of Agriculture, Agricultural Research Service, National Soil Dynamics Laboratory, 411 South Donahue Drive, Auburn, Alabama, 36832, USA
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