Unsaturated Water Flow Through a Simulated Wheel Track1

Reicosky, D. C.; Voorhees, W. B.; Radke, J. K.

doi:10.2136/sssaj1981.03615995004500010001x

Cited by 58 publications

(46 citation statements)

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“…Soil compaction refers to the process in which soil pores, especially macropores, are destroyed and surface aggregates are broken down. Machine traffic may therefore result in a decrease of soil pore volume, a loss of pore continuity, and rut formation (e.g., Berli et al 2003), inducing changes in soil aeration (Gaertig et al 2002), soil water retention, and hydraulic conductivity (e.g., Reicosky et al 1981). Bulk density (e.g., Cullen et al 1991) and penetration resistance (e.g., Aust et al 1998) also increase when the soil is compacted.…”

Section: Introductionmentioning

confidence: 99%

Impact of mechanized harvesting on compaction of sandy and clayey forest soils: results of a meta-analysis

Ampoorter

Schrijver

Nevel

et al. 2012

Annals of Forest Science

109

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Context Nowadays, harvest operations are predominantly performed fully mechanized using heavy tractors or forestry machines. The resulting soil compaction may negatively affect the soil ecosystem. Aims We wanted to draw general conclusions concerning the impact of mechanized harvesting on forest soil bulk density and the influencing factors. Method Therefore, we combined the data of several studies using a meta-analysis approach. Results The impact decreased from the surface towards deeper soil layers. At 0–10 cm depth, the impact on clayey soils was highest although not significantly different from the impact on sandy soils. Higher initial bulk densities, i.e., on already compacted forest soils, generally led to smaller extra increases of bulk density after machine traffic. For sandy soils, the impact was also significantly smaller when machines were lighter. No significant relationship was observed between the compaction degree and traffic intensity. Conclusions We observed clear compaction on both clayey and sandy soils, especially in case of low initial soil compaction degrees and heavy machines. The compacted initial state of many forest soils, the long recovery period, and the generally high impact of the first passes that is frequently mentioned in literature all count in favour of designated skid trails and an adjustment of the machine type to the job.

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Section: Introductionmentioning

confidence: 99%

Impact of mechanized harvesting on compaction of sandy and clayey forest soils: results of a meta-analysis

Ampoorter

Schrijver

Nevel

et al. 2012

Annals of Forest Science

109

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“…The drained pore volume [24] and hydraulic conductivity under saturated conditions [22,11] are both seen to decrease while the penetration resistance increases [6,15]. Consolidation of a soil reduces its aeration, increases its mechanical strength and restricts the length and density of roots [1,25].…”

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confidence: 99%

Mechanical behaviour of silty clay loam/peat mixtures: cyclic compression-release tests and effects of initial water content

Vidal-Beaudet¹,

Charpentier²

1998

Agronomie

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-The mechanical properties of a silty clay loam (SCL), alone or amended with 20 or 40 % by volume of spaghnum peat, were studied at different values of water content. Cyclic uniaxial compression tests were applied using pressures of 30-500 kPa. The void ratios in the last 80 cycles are well represented by a simple function which assumes a limit value for an infinite number of cycles. The void ratio of moist or very moist silty clay loam compressed at 500 kPa is increased to about 55 and 115 % for 20 and 40 % peat contents, respectively. A comparison of the cyclic test with an oedometer (consolidometer) test yields similar results under unsaturated conditions. When the initial degree of saturation is greater than 0.5 and the initial void ratio is greater than 0.9, the compactibility is seen to increase for all the studied materials. A mixing model is used to study SCL and

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“…The first contains five soil types: Columbia sandy loam, Touchet silt loam, and unconsolidated sand [Laliberte et al, 1966], Barnes loam [Reicovsky et al, 1980], Kitasato sandy loam [Moroizumi and Horino, 2004], and Cascavel and Palotina clays [Assouline et al, 1997]. Details on the data for these soils are given by Assouline [2006aAssouline [ , 2006b.…”

Section: Experimental Data and Methodologymentioning

confidence: 99%

Air entry–based characteristic length for estimation of permeability of variably compacted earth materials

Assouline

Or²

2008

Water Resources Research

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[1] The permeability k of a porous medium is a geometrical pore space attribute required for quantifying fluid flows and transport processes for hydrological, civil, agriculture, and petroleum engineering applications. Permeability is often expressed as proportional to a characteristic length squared and inversely proportional to factors accounting for porosity, pore shape, and tortuosity effects. Compaction and diagenesis reduce porosity, mean pore size, and connectivity, resulting in decrease in k. Permeability prediction relies on suitable selection of a characteristic length that may vary from simple hydraulic radius approximation of Kozeny-Carman to more complex critical path analysis to identify flow-limiting pore size. For porous media undergoing significant changes in pore space (e.g., compaction due to anthropogenic activities), the proper choice of a robust characteristic length is particularly challenging. We propose using the air entry pressure, a natural characteristic length that gauges the largest drainable pore size. This choice of a characteristic length is compatible with the Aissen formula that provides robust estimates of k for complex pore shapes. Additionally, the model considers geometrical (tortuosity) factors and links relative changes in porosity to concurrent changes in k. The model was tested against experimental data for sands, sandstones with different cementing agents, and unconsolidated soils. For unconsolidated sands and soils the model provides reasonable predictions of permeability for the entire range of porosities determined in laboratory or field experiments. However, for sandstones, and especially those containing cementing agents such as clay, the model is valid up to a critical porosity where hydraulic connectivity is lost, resulting in drastic reduction in k. The geometrical factor for soils was influenced by silt-to-clay ratio, while for sands, it was correlated with mean grain diameter. The model offers improvement in predicting k and provides a means for incorporating critical pore size and connectivity information in addition to porosity.

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Unsaturated Water Flow Through a Simulated Wheel Track1

Cited by 58 publications

References 0 publications

Impact of mechanized harvesting on compaction of sandy and clayey forest soils: results of a meta-analysis

Impact of mechanized harvesting on compaction of sandy and clayey forest soils: results of a meta-analysis

Mechanical behaviour of silty clay loam/peat mixtures: cyclic compression-release tests and effects of initial water content

Air entry–based characteristic length for estimation of permeability of variably compacted earth materials

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