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Analysing the impact of compaction of soil aggregates using X-ray microtomography and water flow simulations

Menon, M.; Jia, X.; Lair, G. J.; Faraj, P. H.; Blaud, A.

Authors

M. Menon

X. Jia

G. J. Lair

P. H. Faraj



Abstract

Soil aggregates are structural units of soil, which create complex pore systems controlling gas and water storage and fluxes in soil. Aggregates can be destroyed during swelling and shrinking or by external forces like mechanical compaction and yet, the knowledge of how physical impact alters aggregate structure remains limited. The aim of the study was to quantify the impact of compaction on macroaggregates, mainly on the pore size distribution and water flow. In this study, aggregates (2–5 mm) were collected by dry sieving in grassland of the Fuchsenbigl–Marchfeld Critical Zone Observatory (Austria). The structural alterations of these soil aggregates under controlled compaction were investigated with a non-invasive 3D X-ray microtomography (XMT). The detailed changes in pore size distribution between aggregates (interpores, diameter >90 μm) and within the aggregates (intrapores, diameter ≤90 μm) in pre- and post-compacted soils were revealed at two soil moisture (9.3% and 18.3% w/w) and two bulk density increments (0.28 and 0.71 g cm−3 from the initial values). The soil permeability was simulated using lattice Boltzmann method (LBM) based on 3D images. Soil compaction significantly reduced total pores volume and the proportion of interpores volume and surface area, while total pore surface area and the proportion of intrapores volume and surface area increased. The increases in soil moisture tended to reduce the effects of compaction on interpores and intrapores, while the high compaction increment drastically changed the pore size distribution. The aggregate compaction decreased water penetration potential due to the increase of small intra-aggregate pores and cavities as demonstrated by LBM. Notably, the LBM results showed a significant linear correlation between the water flow rate and bulk density of soil aggregates and predicted that the water flow could be reduced by up to 97–99% at bulk density of ≥1.6 g cm−3 with soil water content of 18.3% w/w. Thus, a combination of imaging and modelling provided new insights on the compaction effects on aggregates, underpinning the importance of protecting soil structure from mechanical compaction to minimise environmental impacts of soil compaction and maintain water infiltration and percolation in arable soils.

Citation

Menon, M., Jia, X., Lair, G. J., Faraj, P. H., & Blaud, A. (2015). Analysing the impact of compaction of soil aggregates using X-ray microtomography and water flow simulations. Soil and Tillage Research, 150, 147-157. https://doi.org/10.1016/j.still.2015.02.004

Journal Article Type Article
Acceptance Date Feb 4, 2015
Online Publication Date Feb 14, 2015
Publication Date 2015-07
Deposit Date Aug 6, 2019
Publicly Available Date Aug 6, 2019
Journal Soil and Tillage Research
Print ISSN 0167-1987
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 150
Pages 147-157
DOI https://doi.org/10.1016/j.still.2015.02.004
Keywords Earth-Surface Processes; Agronomy and Crop Science; Soil Science
Public URL http://researchrepository.napier.ac.uk/Output/1348557
Publisher URL https://www.sciencedirect.com/science/article/pii/S0167198715000392
Contract Date Aug 6, 2019

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