A study on the effect of compaction on transport properties of soil gas and water. II: Soil pore structure indices

Download A study on the effect of compaction on transport properties of soil gas and water. II: Soil pore structure indices

Post on 05-Jan-2017

212 views

Category:

Documents

0 download

TRANSCRIPT

  • Soil & Tillage Research xxx (2014) xxxxxx

    G Model

    STILL-3255; No. of Pages 8A study on the effect of compaction on transport properties of soil gasand water. II: Soil pore structure indices

    P.H. Kuncoro a,c,*, K. Koga b, N. Satta b, Y. Muto b

    a The United Graduate School of Agricultural Sciences, Iwate University, 3-18-8 Ueda, Morioka 020-8550, Japanb Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka 020-8550, Japanc Faculty of Agriculture, Jenderal Soedirman University, Purwokerto 53123 Central Java, Indonesia

    A R T I C L E I N F O

    Article history:

    Received 1 September 2013

    Received in revised form 2 December 2013

    Accepted 18 January 2014

    Keywords:

    Soil compaction

    Applied organic matter

    Pore size distribution

    Pore organization

    A B S T R A C T

    Experimental data on the effects of compaction and applied organic matter (OM) on macropore structure

    indices, more particularly on pore continuity, have yet rarely been documented. In this study, static

    compaction was simulated in the laboratory at 150, 225, and 300 kPa upon rice husk, rice straw,

    compost, sawdust, and wood bark-mixed soils and control. Measurements of relative gas diffusivity (Dp/

    D0)100 and air permeability (ka100) were conducted at 100 cm H2O soil matric suction aftermeasurement of saturated hydraulic conductivity (ks). Corresponding dry bulk density (rd), totalporosity (f), and air content (e100) values were also determined. Volume of macropores (f 30 mm) andmicropores (f < 30 mm) were expressed as volume of air and water at 100 cm H2O soil matric suction,respectively, relative to the volume of soil solid. Specific gas diffusivity (SD100) and specific air

    permeability (Ska100) were calculated as (Dp/D0)100/e100 and ka100/e100, respectively. Analogous to theSD100 and Ska100, specific hydraulic conductivity (Sks) was defined as ks/e100. The results showed thatcompaction significantly increased rd, which was followed by a reduction in f, and the mixed OMresulted in a significantly lower rd and higher f than the control. The volume of macropores was reducedby compaction whereas the volume of micropores remained unaffected, for which the mixed OM tended

    to result in a higher volume of macropores than the control. Compaction resulted in more tortuous

    macropores for gas diffusion (lower SD100) and less continuous macropores for gas convection (lower

    Ska100) for which a significant difference was more pronounced between the 300 and 150 kPa

    compactions. Compaction also resulted in fewer continuous macropores for water movement as

    indicated by lower Sks. The mixed OM was likely to result in a lower SD100, but except for rice straw

    tended to result in a higher Ska100 than the control. In addition, the mixed OM also seemed to result in a

    higher Sks than the control. Of the OM-mixed soils, the decrease in (Dp/D0)100 and ka100 was more

    sensitive to compaction (i.e., decrease in e100) than that of the control whereas the decrease in ks actedconversely. Discussion of the measured (Dp/D0)100, ka100, and ks is presented in the companion paper.

    2014 Elsevier B.V. All rights reserved.

    Contents lists available at ScienceDirect

    Soil & Tillage Research

    jou r nal h o mep age: w ww.els evier . co m/lo c ate /s t i l l1. Introduction

    The soil compaction process is defined as a simple operation of achange in volume for a given mass of soil due to an applied load(McKibben, 1971) for which the volume of soil solid and liquiddo not undergo an appreciable change (Harris, 1971). The volumechange takes place in the gas phase of soil and is mostlyattributable to a decrease in soil macropores (e.g., Alakukku,1996; Alaoui et al., 2011; Berisso et al., 2012).* Corresponding author at: The United Graduate School of Agricultural Sciences,

    Iwate University, Environmental Sciences for Sustainability, Ueda 3-18-8, Morioka

    0208550, Iwate Prefecture, Japan. Tel.: +81 19 621 6189/+81 90 284 28224;

    fax: +81 19 621 6107.

    E-mail address: kuncoro.hari@yahoo.com (P.H. Kuncoro).

    Please cite this article in press as: Kuncoro, P.H., et al., A study on the eII: Soil pore structure indices. Soil Tillage Res. (2014), http://dx.doi.o

    http://dx.doi.org/10.1016/j.still.2014.01.008

    0167-1987/ 2014 Elsevier B.V. All rights reserved.To evaluate this volume change, the air volume of a compactedsoil specimen may then be expressed in a form analogous to theexpression of water volume ratio (in common textbook, e.g.,Hillel, 1998) as a proportion of the relatively constant solid volumeof the soil, termed air volume ratio, as shown in the followingequation:

    va VaVs

    (1)

    where va is air volume ratio, Va is volume of air (cm3), and Vs is

    volume of soil solid (cm3). Rather than expression of soil aircontent or air-filled porosity (i.e., quotient of Va and total volumeof soil), the expression air volume ratio might be preferable todescribe the actual change in air volume by compaction, namelythe change in air volume of a given soil layer by compaction can beffect of compaction on transport properties of soil gas and water.rg/10.1016/j.still.2014.01.008

    http://dx.doi.org/10.1016/j.still.2014.01.008mailto:kuncoro.hari@yahoo.comhttp://dx.doi.org/10.1016/j.still.2014.01.008http://www.sciencedirect.com/science/journal/01671987www.elsevier.com/locate/stillhttp://dx.doi.org/10.1016/j.still.2014.01.008

  • a) continuous &non tortuous

    b) continuous &tortuous

    c) constricted orbottle necked

    d) tentatively notconnected

    e) dead ended orconfined

    Fig. 1. Simplified qualitative model of soil macropores arrangement through whichsoil air and water may be transported.

    Table 1Physical properties of the soil samples.

    Organic matter content (%) 20.2

    Gravimetric water content (g g1) 0.70

    Particle density (g cm3) 2.52

    Dry bulk density (g cm3) 0.700

    Texture: Sand [20.02 mm] (%) 72.5

    Silt [0.020.002 mm] (%) 16.1

    Clay [

  • P.H. Kuncoro et al. / Soil & Tillage Research xxx (2014) xxxxxx 3

    G Model

    STILL-3255; No. of Pages 8where hc is the capillary rise (cm), r is radius of the capillarytube (cm), and a is the contact angle (8), which is taken as zero forsoil.

    2.3. Determination of soil pore structure indices

    For quantitative evaluation of soil pore organization, Groene-velt et al. (1984) introduced quotient of air permeability and soilair content as a pore continuity index, which was further used inBall et al. (1988), Blackwell et al. (1990), and Dorner et al. (2012).The authors term the index specific air permeability in this studyafter Schjnning et al. (2005) as seen in the following equation:

    Ska kae

    (3)

    in which Ska is specific air permeability (mm2), ka is air permeability

    (mm2), and e is air-filled porosity namely air content (cm3 cm3).The pore continuity index of soil may also be expressed in terms

    of gas diffusion, which is more attributable to the pore tortuosity.This concept was first implied in the study of Gradwell (1961) andfurther used by other researchers (e.g., Ball, 1981; Ball et al., 1988;Schjnning, 1989; Schjnning et al., 2005). In this study, the indexwas termed specific gas diffusivity as in Schjnning et al. (2005) asseen in the following equation:

    SD Dp=D0

    e(4)

    in which SD is the specific gas diffusivity and Dp/D0 is the relativegas diffusivity.

    When the soil is fully saturated with water, macropores are thealmost exclusive determinant of transport process of this soilwater (Iversen et al., 2003; Kuncoro et al., 2014; Poulsen et al.,1999). Accordingly, by analogy with ka and Dp/D0, the followingindex (Eq. (5)) can be defined for quantifying the macroporecontinuity in terms of saturated hydraulic conductivity:

    Sks kse100

    (5)

    where Sks is specific hydraulic conductivity (cm s1), ks is

    saturated hydraulic conductivity (cm s1), and e100 is volume ofmacropores namely air content measured at 100 cm H2O soilmatric suction (cm3 cm3).

    Ahuja et al. (1984) have successfully used a generalizedKozenyCarman equation to characterize spatial distribution ofsaturated hydraulic conductivity (ks) from measurements ofeffective porosity (fe) (or macroporosity) as seen in the followingequation:

    ks Bfne (6)

    where B and n are empirical constants, and fe is the subtraction ofsoil water content at a pressure head of 33 kPa from totalporosity. The exponent n is the slope or tangent of the fitted linethrough the loglog graph of ks vs. fe (ks: fe characteristic), andTable 2Arithmetic mean and standard deviation of dry bulk density (rd) and total porosity (f)

    OM treatment rd (g cm3)

    150 kPa 225 kPa 300 kPa

    Control 0.667 0.001 Ba 0.693 0.005 Ca 0.717 0.00Rice husk 0.633 0.005 Bd 0.664 0.004 Cc 0.688 0.00Rice straw 0.621 0.003 Bc 0.653 0.010 Cc 0.680 0.00Compost 0.624 0.006 Bcd 0.654 0.006 Cc 0.687 0.01Sawdust 0.604 0.007 Bb 0.632 0.006 Cb 0.661 0.00Wood bark 0.617 0.002 Bc 0.655 0.003 Cc 0.679 0.00

    Either values of rd or f followed by same capital letter (row), and lowercase letter (col

    Please cite this article in press as: Kuncoro, P.H., et al., A study on the eII: Soil pore structure indices. Soil Tillage Res. (2014), http://dx.doi.otherefore, expresses the sensitivity of kswith regard to fe. In a formanalogous to this concept, sensitivity of the measured Dp/D0 and kaat 100 cm H2O soil matric suction as well as kswith regard to e100in this study can be studied from the loglog graph of (Dp/D0)100 vs.e100, ka100 vs. e100, and ks vs. e100, respectively.

    2.4. Statistical analysis

    Statistical significance of compaction levels and OM treatmentswere analyzed using KaleidaGraph 4.1 software (Synergy Software2012, USA) for the analysis of variance (ANOVA) test. Post-hocanalysis was performed using the Tukey HSD test (P < 0.05).

    3. Results and discussion

    3.1. Dry bulk density (rd) and total porosity (f)

    Soil dry bulk density (rd) significantly increased with increasedlevels of compaction and consequently was followed by areduction in total porosity (f) as shown in Table 2. This resultwas in good agreement with Botta et al. (2009) who found that asignificant increase in rd and reduction in f was observed,particularly at the topsoil layer, after several passages with 5.8and 4.8 Mg in total weight of tractors on fine clayey soil. Hassanet al. (2007) also reported a significant increase in rd and decreasein f of alluvial silt loam soil after compaction using a 7.0-Mg self-propelled steel roller for 2, 4, and 6 passes. In Abu-Hamdeh and Al-Jalil (1999), rd and f of a clay loam soil were found to significantlyincrease and decrease, respectively, even down to a depth of 50 cmafter three passes of a tractor with a 1.5-Mg planter mounted.

    Almost all data in Table 2 showed that the addition of OM tosoils resulted in significantly lower rd and higher f than the control,and only for rice husk and compost-mixed soils at 300 kPa were thedifferences in f not statistically significant. Among the OMadditions, sawdust and rice husk addition led to the lowest andhighest rd values, respectively, and consequently had a converseeffect upon f (Table 2). Compost-mixed soil, in particular, led to asimilarly low f as rice husk-mixed soil, despite the lower rd incompost-mixed soil compared with that of rice husk-mixed soil.This result suggested a positive effect of the mixed OM on either rdor f even after the compaction took place. In accordance with thisresult, Celik et al. (2004) also reported a significant decrease in rdand an increase in f within 030 cm soil depth after 5-yearapplication of compost and farm manure on a clay-loam soil withOM content ranged from 1.4% to 1.6%. Schjnning et al. (2005) alsoobserved a significantly larger f (in average) of a loamy sand soilsupplied with animal manure for about a century (1.301.35% inOM content) compared with soil with no addition (1.07% in OMcontent).

    3.2. Pore size distribution

    In order to examine the effect of compaction, the volume ofmacropores (f 30 mm) is expressed in a measure relative to the of the compacted soil at 150, 225, and 300 kPa compaction levels.

    f (cm3 cm3)

    150 kPa 225 kPa 300 kPa

    5 Aa 0.735 0.000 Ab 0.725 0.002 Cb 0.715 0.002 Bb2 Ad 0.744 0.002 Ac 0.732 0.002 Cc 0.722 0.001 Bab8 Abd 0.750 0.001 Aa 0.737 0.004 Cac 0.726 0.003 Bac2 Acd 0.745 0.002 Ac 0.732 0.002 Cc 0.719 0.005 Bbc7 Ab 0.753 0.003 Aa 0.742 0.003 Ca 0.730 0.003 Ba4 Abd 0.751 0.001 Aa 0.736 0.001 Cac 0.726 0.002 Bac

    umn), are not significantly different (P < 0.05).

    ffect of compaction on transport properties of soil gas and water.rg/10.1016/j.still.2014.01.008

    http://dx.doi.org/10.1016/j.still.2014.01.008

  • Table 3Effect of compaction on distribution of macro and micro-pores as indicated by air volume ratio (va100) and water volume ratio (vw100) at 100 cm H2O soil matric suction,respectively.

    OM treatment na100 (cm3 cm3) [f 30 mm] nw100 (cm3 cm3) [f < 30 mm]

    150 kPa 225 kPa 300 kPa 150 kPa 225 kPa 300 kPa

    Control 0.70 0.01 Ab 0.58 0.05 Cb 0.45 0.04 Bab 2.08 0.01 Abc 2.05 0.03 Abc 2.06 0.04 AaRice husk 0.90 0.07 Aa 0.71 0.05 Cac 0.56 0.06 Bac 2.01 0.04 Ab 2.02 0.04 Ab 2.04 0.07 AaRice straw 0.79 0.06 Aab 0.62 0.04 Cbc 0.43 0.03 Bbc 2.21 0.06 Aa 2.18 0.08 Aa 2.22 0.04 AaCompost 0.72 0.04 Ab 0.56 0.04 Ab 0.38 0.10 Bb 2.20 0.06 Aac 2.17 0.06 Aac 2.18 0.16 AaSawdust 0.92 0.09 Aa 0.80 0.05 Aa 0.59 0.05 Ba 2.13 0.04 Aab 2.08 0.01 Aab 2.11 0.04 AaWood bark 0.93 0.04 Aa 0.71 0.01 Cac 0.58 0.04 Bac 2.09 0.04 Aab 2.07 0.03 Aab 2.07 0.04 Aa

    Either values of va100 or vw100 followed by same capital letter (row), and lowercase letter (column), are not significantly different (P < 0.05).

    P.H. Kuncoro et al. / Soil & Tillage Research xxx (2014) xxxxxx4

    G Model

    STILL-3255; No. of Pages 8volume of soil solid using va100 (Table 3). It was found that thevolume of macropores decreased with increased levels ofcompaction, and a significant difference was more pronouncedbetween the 300 and 150 kPa compactions. The volume ofmicropores (f < 30 mm), however, did not undergo an appreciablechange (vw100). If the volume of macropores is expressed in ameasure relative to the total volume of soil using e100 (Table 4), itdecreased with the increased level of compaction, and likewise, thedifference was found to be particularly significant between the 300and 150 kPa compactions. This decrease in macropores wasfollowed by an increase in volume of micropores (f < 30 mm)as indicated by the increased u100 in Table 4. These resultssuggested that compaction decreased the volume of macroporeseither as a proportion to the solid volume of soil (va100) or as aproportion to the total volume of soil (e100), whereas the volume ofmicropores seemed to be subject to the volume indices being used,namely vw100 or u100. To appreciate the volume change thatactually occurred when a soil specimen was compacted, it might bepreferable to summarize here that the volume of macroporesdecreased with the level of compaction (va100), while the volume ofmicropores did not undergo an appreciable change (vw100) in thisstudy. This summation was consistent with the result of Kutleket al. (2006) that the change of pore size distribution is mainly inthe macropores system (structural domain), while it is negligible inthe micropores system (matrix domain), after their study on asandy loam Alfisol soil subjected to 0 and 300 kPa compression.

    The results shown in Table 4 were in accordance with the studyfrom Alakukku (1996) who found that wheeling with 19 Mg of atractor-trailer combination was found to reduce macroporosity(f > 30 mm) of a clay soil. Furthermore, an organic soil was foundto have a reduced macroporosity and an increased microporosity(f < 30 mm) over 2050 cm soil depth after wheeling with a 16-Mg tractor-trailer combination. Berisso et al. (2012) also observeda reduction in volume of macropores (f > 30 mm) of a sandy clayloam soil after repeated wheelings with an 10 Mg sugar beetharvester. Matthews et al. (2010) found that a 522 kPa compactioncaused a greater loss of larger pores (f > 30 mm) in clay loam, siltyTable 4Effect of compaction on distribution of macro and micro-pores as indicated by air cont

    respectively.

    OM treatment e100 (cm3 cm3) [f 30 mm]

    150 kPa 225 kPa 300 kPa

    Control 0.186 0.003 Ab 0.160 0.013 Cbd 0.128 0.0Rice husk 0.230 0.016 Aa 0.191 0.012 Bac 0.156 0.0Rice straw 0.198 0.014 Aab 0.164 0.013 Cbc 0.119 0.0Compost 0.183 0.011 Ab 0.151 0.011 ABb 0.106 0.0Sawdust 0.227 0.019 Aa 0.205 0.010 Aa 0.160 0.0Wood bark 0.230 0.010 Aa 0.189 0.004 Cacd 0.159 0.0

    Either values of e100 or u100 followed by same capital letter (row), and lowercase lette

    Please cite this article in press as: Kuncoro, P.H., et al., A study on the eII: Soil pore structure indices. Soil Tillage Res. (2014), http://dx.doi.clay loam, and clay loam soil than a 174-kPa compaction, whereasthe smaller pores remained unaffected.

    With the purpose of discussing the effect of OM, Table 4 wasexamined. It was observed that the compost-mixed soil had thelowest volume of macropores (even lower than the control),whereas the other OM treatments tended to result in a highervolume of macropores than the control even though the differencewas not consistent. This result implied that the OM treatments(other than compost) have a positive effect on the volume ofmacropores in terms of resistance to compaction. This positiveeffect could be related to the capability of OM in increasing aloading or mechanical stress resistance as described in the study ofEllies (1988), Gregory et al. (2009), and Dorner et al. (2011) aftertheir study on volcanic ash and grassland soils.

    The compost-mixed soil, conversely, had the highest volume ofmicropores, and together with rice straw-mixed soil, had a highervolume of micropores than the control (Table 4). Celik et al. (2004)also reported a higher volume of micropores due to the applicationof compost for 5 years on a clay-loam soil (OM content 1.41.6%).In their study, however, the volume of macropores (f > 4.5 mm)was also observed to significantly increase. Similarly, Schjnninget al. (1994) and Schjnning et al. (2005) reported a significantlylarger volume of micropores (f < 30 mm) in soil dressed withanimal manure (1.32% and 1.301.35% in OM content, respective-ly) than in soil dressed with inorganic fertilizers (1.19% and 1.151.25% in OM content, respectively), but the volume of macropores(f > 30 mm) remained unaffected.

    In order to examine the pore size distribution of eithermacropores or micropores for more specific diameter ranges, aset of pF tests was conducted in this study. The results revealedthat the decrease in volume of macropores occurred for allmacropore diameter ranges measured (>300 mm, 30095 mm,9530 mm) after compaction, but there was no pattern ofsignificance observed among either the compaction levels or thetype of OM applied (data and statistical analysis not shown). In thecase of the micropores, a relatively constant volume was observedfor the size ranges

  • 0

    0.05

    0.1

    0.15

    0.2

    0.25

    150 kPa 225 kPa 300 kPa

    Controla

    ab

    b

    0

    0.05

    0.1

    0.15

    0.2

    0.25

    150 kPa 225 kPa 300 kPa

    Rice hus k

    a

    ab

    b

    0

    0.05

    0.1

    0.15

    0.2

    0.25

    150 kPa 225 kPa 300 kPa

    Rice stra w

    aab

    b

    S D10

    0

    0

    0.05

    0.1

    0.15

    0.2

    0.25

    150 kPa 225 kPa 300 kPa

    Compo st

    a

    ab

    b

    0

    0.05

    0.1

    0.15

    0.2

    0.25

    150 kPa 225 kPa 300 kPa

    Sawdust

    aab

    b

    0

    0.05

    0.1

    0.15

    0.2

    0.25

    150 kPa 225 kPa 300 kPa

    Wood bark

    a

    ab

    b

    S D10

    0

    Fig. 2. Specific gas diffusivity (SD100) at 100 cm H2O soil matric suction as a function of compaction levels. Means for the compaction levels of a certain OM treatmentfollowed by same letter are not significantly different (P < 0.05).

    (Dp

    /D0)

    100

    control

    soil+OM

    |r|=0.8 98* *

    100 (cm3 cm-3)

    (Dp /D0)100=1.95 ( 100) 2.31

    (Dp /D0)100=9.46 ( 100)3.50

    |r|=0.90 8**

    10-110-4

    10-3

    10-2

    10-1

    Fig. 3. Sensitivity of the measured relative gas diffusivity at 100 cm H2O soilmatric suction (Dp/D0)100 with regard to the corresponding air content (e100) (**

    P < 0.01).

    P.H. Kuncoro et al. / Soil & Tillage Research xxx (2014) xxxxxx 5

    G Model

    STILL-3255; No. of Pages 8change in volume was observed for the pores ranging from 3.0 to30 mm.

    3.3. Specific gas diffusivity (SD100)

    As the level of compaction increased, specific gas diffusivity(SD100) measured at 100 cm H2O soil matric suction decreasedand a significant difference was found between 300 and 150 kPa(Fig. 2). This result implied that compaction led to a more tortuouspore network for gas diffusion, which may have resulted in lowerrelative gas diffusivity (Dp/D0). To some extent, the more tortuouspores (lower SD100) were likely to have contributed to the lower(Dp/D0)100 in Kuncoro et al. (2014) after the compaction took place.A reduction in SD due to compaction was also reported bySchjnning and Rasmussen (2000) after compaction with directdrilling using a triple-disc drill on a coarse sandy soil at 48 and1418 cm depth and for a loamy sand soil at 48 cm depth. Ballet al. (1988) also reported a lower SD of either chisel ploughed ordirect drilled clay loam soil after traffic treatment using an unladentractor.

    The addition of OM tended to result in more tortuous pores forgas diffusion than the control, as indicated by lower values of SD100(Fig. 2), even though the difference was generally not significant(data and statistical analysis not shown). The most tortuous poreswere observed in the rice straw-mixed soil (significantly differentfrom the control at 150 and 225 kPa compaction). This may explainthe low value of (Dp/D0)100 of this soil despite its high air content(Kuncoro et al., 2014). Conversely, despite their slightly lowervalues of SD100, sawdust and wood bark-mixed soils resulted inhigher (Dp/D0)100 (e.g., 0.0480 and 0.0477 at 150 kPa, respectively)than the control (e.g., 0.0425 at 150 kPa) in Kuncoro et al. (2014).This result might imply that their higher (Dp/D0)100 were morelikely ascribed to the higher air content (Kuncoro et al., 2014), andthus, the pore tortuosity may not necessarily be providing asignificant contribution.Please cite this article in press as: Kuncoro, P.H., et al., A study on the eII: Soil pore structure indices. Soil Tillage Res. (2014), http://dx.doi.oThis result, however, was different from Schjnning et al.(2005) who found that there was a tendency for a reducedtortuosity (higher SD) of the loamy sand soil with a long-term(about a century) application of animal manure and mineralfertilizer (1.151.35% in OM content) than the unfertilized soil(1.07% in OM content). This difference was attributable to thedifference in the type of OM applied and the type of soil observedbesides observation in the present study was limited to the veryearly period of OM application so that a prolonged observationis expected to give a different result after the applied OMdecomposes.

    It can be seen from Fig. 3 that the OM-mixed soils tended toresult in lower (Dp/D0)100 than the control for a given e100, whichmight suggest an existence of blockage effects from the presenceof OM on gas diffusion namely the mixed OM itself and theincreased capillary water in the bottle-neck may give a hindranceto the gas diffusion process (Kuncoro et al., 2014). The OM-mixedffect of compaction on transport properties of soil gas and water.rg/10.1016/j.still.2014.01.008

    http://dx.doi.org/10.1016/j.still.2014.01.008

  • 0

    10

    20

    30

    40

    50

    150 kPa 225 kPa 300 kPa

    Control

    a

    ab

    b

    0

    10

    20

    30

    40

    50

    150 kPa 225 kPa 300 kPa

    Rice hus k

    a

    ab

    b

    0

    10

    20

    30

    40

    50

    150 kPa 225 kPa 300 kPa

    Rice stra w

    a

    c

    b

    S ka1

    00(

    m2 )

    0

    10

    20

    30

    40

    50

    150 kPa 225 kPa 300 kPa

    Compo st

    a

    ab

    b

    0

    10

    20

    30

    40

    50

    150 kPa 225 kPa 300 kPa

    Sawdust

    a

    ab

    b

    0

    10

    20

    30

    40

    50

    150 kPa 225 kPa 300 kPa

    Wood barka

    b

    b

    S ka1

    00(

    m2 )

    Fig. 4. Specific air permeability (Ska100) at 100 cm H2O soil matric suction as a function of compaction levels. Means for the compaction levels of a certain OM treatmentfollowed by same letter are not significantly different (P < 0.05).

    P.H. Kuncoro et al. / Soil & Tillage Research xxx (2014) xxxxxx6

    G Model

    STILL-3255; No. of Pages 8soils also had a higher value of n (3.50) than that of the control (2.31).This higher value of n implied a steeper decrease in (Dp/D0)100 withthe level of compaction (i.e., decrease in e100). Thus, (Dp/D0)100 of theOM-mixed soils were more sensitive to the change in e100 comparedwith that of the control, and this was probably related to theexistence of the aforementioned blockage effect.

    3.4. Specific air permeability (Ska100)

    Specific air permeability (Ska100) measured at 100 cm H2O soilmatric suction decreased with compaction level, and a significantdifference was more pronounced between 300 and 150 kPa (Fig. 4).This result confirmed that compaction had a negative effect on soilpore continuity (Ska) by which gas convection might be constrainedso that the measured air permeability (ka) would be reduced. Thus,the reduced ka100 in Kuncoro et al. (2014) was also thought to bereasonable to attribute to the reduced pore continuity (lowerSka100).

    A reduction in pore continuity caused by compaction has alsobeen reported by other researchers. Dorner et al. (2012)demonstrated that compaction with a 1.5-Mg roller caused adecrease in continuity of macropores (Ska) of silty loamsilty clayloam volcanic ash soil. Ball et al. (1988) also revealed a reduction inSka of a direct drilled clay loam soil after traffic treatment using anunladen tractor. Arthur et al. (2013) reported a negativerelationship between soil bulk density and pore organization(Ska) at 100 hPa (field capacity) of silt loam soil with long-termapplication of animal manure and mineral fertilizer. Furthermore,they observed that it was the soil bulk density, rather than theorganic content, that seemed to differentiate the pore connectivityand arrangement. Schjnning and Rasmussen (2000) reported areduced Ska of coarse sandy soil and loamy sand soil aftercompaction by direct drilling using a triple-disc drill.

    Although it was not statistically significant, there was atendency toward higher pore continuity (higher Ska100) of thePlease cite this article in press as: Kuncoro, P.H., et al., A study on the eII: Soil pore structure indices. Soil Tillage Res. (2014), http://dx.doi.OM-mixed soils than the control except for rice straw-mixed soil(data and statistical analysis not shown). This result might imply apositive effect of the mixed OM on the pore continuity, moreparticularly that of sawdust and wood bark, so that higher airpermeability (ka100) might be the result. This higher porecontinuity of sawdust and wood bark-mixed soils was inaccordance with the remarkably high ka100 in Kuncoro et al.(2014). A similar positive effect of the applied OM on porecontinuity (Ska) has also been reported by Schjnning et al. (2005)after their study on a loamy sand soil dressed with animal manureand mineral fertilizer for about a century (1.151.35% in OMcontent). Similarly, Arthur et al. (2013) also reported an increase inpore connectivity (Ska) of silt loam soil after a 105-year animalmanure and mineral fertilizer application (1.532.37% in OMcontent).

    The rice straw-mixed soil, conversely, gave the lowest Ska100(least continuous pores) which was also in accordance with thelowest ka100 in Kuncoro et al. (2014). This result, however, wasdifferent from the result described by Schjnning et al. (2005)that incorporation of rice straw for years led to a tendencytoward higher air permeability (ka) and pore continuity (Ska).Likewise, this difference was probably due to the difference intype of soil observed and period length of the rice strawapplication.

    For a given e100, the ka100 value of the control tended to behigher than that of the OM-mixed soils (Fig. 5). This result mightimply the existence of a blockage effect from the presence of OMon gas convection (ka) as in the case of gas diffusion (Dp/D0)(Kuncoro et al., 2014). The OM-mixed soils had a slightly highervalue of n (4.16) than that of the control (3.76), which to someextent implied a steeper decrease in ka100 with the level ofcompaction (i.e., decrease in e100). In other words, ka100 values ofthe OM-mixed soils were more sensitive to changes in e100 thanthat of the control, which can probably be ascribed to the existingblockage effect from the presence of OM.ffect of compaction on transport properties of soil gas and water.org/10.1016/j.still.2014.01.008

    http://dx.doi.org/10.1016/j.still.2014.01.008

  • k a10

    0 (m

    2 )

    control

    soil+OM

    |r|=0.9 50* *

    100 (cm3 cm-3)

    ka10 0=5081 ( 100) 4.16

    ka10 0=3741 ( 100) 3.76

    |r|=0.92 1**

    10-1

    10-1

    100

    101

    Fig. 5. Sensitivity of the measured air permeability at 100 cm H2O soil matricsuction (Sa100) with regard to the corresponding air content (e100) (** P < 0.01).

    k s(c

    m s

    -1)

    control

    soil+O M

    |r|=0.82 9**

    100 (cm3 cm-3)

    ks=0.06 ( 100) 2.70

    ks=0.12 ( 100)3.17

    |r|=0.865 **

    10-110-4

    10-3

    10-2

    Fig. 7. Sensitivity of saturated hydraulic conductivity (ks) with regard to the volumeof macropores (e100) (** P < 0.01).

    P.H. Kuncoro et al. / Soil & Tillage Research xxx (2014) xxxxxx 7

    G Model

    STILL-3255; No. of Pages 83.5. Specific hydraulic conductivity (Sks)

    The value of specific hydraulic conductivity (Sks) decreased withthe level of compaction (Fig. 6), which suggested a reduction inmacropore continuity. This result was in accordance with thereduced ks in Kuncoro et al. (2014). Therefore, it became evidentthat the decrease in ks could not merely be ascribed to the lowervolume of macropores (Kuncoro et al., 2014), but also related to thereduced macropore continuity after the compaction took place asdiscussed in Dorner et al. (2010), Fuentes et al. (2004), andOsunbitan et al. (2005) amongst others. As shown in Fig. 6, thedifferences were significant between 300 and 150 kPa compac-tions except for rice straw and sawdust-mixed soils, which gave nosignificant differences among the three compaction levels.Compared with the control, the OM-mixed soils resulted in higherSks, except for rice straw-mixed soil, even though the differencewas not significant (data and statistical analysis not shown). Thisresult implied that the applied OM tended to enable maintenanceof macropore continuity of the compacted soil sample for thehigher ks. In the case of the rice straw-mixed soil, the lower Sks was0

    0.001

    0.002

    0.003

    0.004

    0.005

    0.006

    0.007

    0.008

    150 kPa 225 kPa 300 kPa

    Control

    a

    bb

    0

    0.001

    0.002

    0.003

    0.004

    0.005

    0.006

    0.007

    0.008

    150 kPa

    R

    a

    S ks(c

    m s-

    1 )

    0

    0.001

    0.002

    0.003

    0.004

    0.005

    0.006

    0.007

    0.008

    150 kPa 225 kPa 300 kPa

    Compo st

    a

    b b

    0

    0.001

    0.002

    0.003

    0.004

    0.005

    0.006

    0.007

    0.008

    150 kPa

    S

    a

    S ks(c

    m s-

    1 )

    Fig. 6. Comparison of specific hydraulic conductivity (Sks) at different level of compactionsare not significantly different (P < 0.05).

    Please cite this article in press as: Kuncoro, P.H., et al., A study on the eII: Soil pore structure indices. Soil Tillage Res. (2014), http://dx.doi.oalso coincident with lower ks than the control in Kuncoro et al.(2014). This revealed that the addition of rice straw failed toimprove the status of macropores in terms of continuity for betterks in this study.

    A slightly higher value of n was observed for the control (3.17)than the OM-mixed soils (2.70) as shown in Fig. 7. This resultindicated a steeper decrease in ks with the decrease in e100 (i.e.,decrease in volume of macropores) of the control compared withthe OM-mixed soils. Thus, ks of the control was more sensitive tothe level of compaction (i.e., decrease in volume of macropores)than that of the OM-mixed soils. This result suggested a positiveeffect from the applied OM on the measured ks of the compactedsoil sample, which could be explained through the existence ofceramic filter effect (Kuncoro et al., 2014) for which the soilpores-blocking OM yet allowed water to be permeated undersaturated condition even though they hindered the air transport(blockage effect). The values of n measured in this study (3.17and 2.70), however, were lower than that in Ahuja et al. (1984)where they measured 3.98 and 3.81 for Renfrow silt loam andHawaii oxic soils, respectively. This difference in the value of n was225 kPa 300 kPa

    ice hus k

    b

    b

    0

    0.001

    0.002

    0.003

    0.004

    0.005

    0.006

    0.007

    0.008

    150 kPa 225 kPa 300 kPa

    Rice stra w

    a

    a a

    225 kPa 300 kPa

    awdust

    a

    a

    0

    0.001

    0.002

    0.003

    0.004

    0.005

    0.006

    0.007

    0.008

    150 kPa 225 kPa 300 kPa

    Wood bark

    a

    ab

    b

    . Means for the compaction levels of a certain OM treatment followed by same letter

    ffect of compaction on transport properties of soil gas and water.rg/10.1016/j.still.2014.01.008

    http://dx.doi.org/10.1016/j.still.2014.01.008

  • P.H. Kuncoro et al. / Soil & Tillage Research xxx (2014) xxxxxx8

    G Model

    STILL-3255; No. of Pages 8probably ascribed to the difference in the size range of macroporesbeing considered where we used f 30 mm in this study (e100)and Ahuja et al. (1984) used f > 9.1 mm (i.e., air content measuredat 330 cm H2O soil matric suction e330).

    4. Conclusions

    Compaction significantly increased dry bulk density (rd), whichwas followed by a reduction in total porosity (f), and the addition ofOM resulted in significantly lower rd and higher f than the control.The volume of macropores (f 30 mm) was reduced by thecompaction whereas the volume of micropores (f < 30 mm)remained unaffected. The addition of OM tended to result in ahigher volume of macropores than the control.

    The compaction resulted in more tortuous macropores for gasdiffusion (lower specific gas diffusivity SD100) and less continuousmacropores for gas convection (lower specific air permeabilitySka100) for which a significant difference was more pronouncedbetween the 300 and 150 kPa compactions. The compaction alsocaused less continuous macropores for water movement asindicated by lower specific hydraulic conductivity Sks. The additionof OM was likely to result in lower SD100, but except for rice strawtended to result in higher Ska100 than the control. The addition ofOM also seemed to result in a higher Sks than the control.

    The decrease in relative gas diffusivity (Dp/D0)100 and airpermeability ka100 was more sensitive to compaction (i.e., decreasein e100) in OM-mixed soils than in the control whereas the decreasein saturated hydraulic conductivity ks showed the opposite result.

    Acknowledgments

    This study was funded by The Laboratory of Soil Engineering,Faculty of Agriculture, Iwate University, Japan and The UnitedGraduate School of Agricultural Sciences, Iwate University, Japan.The authors are also grateful to The Ministry of Education, Culture,Sports, Science and Technology of Japan for the scholarship grantedfor the Ph.D. study of the first author. Prof. Takeyuki Annaka isacknowledged for providing meaningful discussions and Dr. KojiHarashina is acknowledged for providing excellent advice onstatistical analyses.

    References

    Abu-Hamdeh, N.H., Al-Jalil, H.F., 1999. Hydraulically powered soil core sampler andits application to soil density and porosity estimation. Soil Till. Res. 52, 113120.

    Ahuja, L.R., Naney, J.W., Green, R.E., Nielsen, D.R., 1984. Macroporosity to charac-terize spatial variability of hydraulic conductivity and effects of land manage-ment. Soil Sci. Soc. Am. J. 48, 699702.

    Alakukku, L., 1996. Persistence of soil compaction due to high axle load traffic. I.Short-term effects on the properties of clay and organic soils. Soil Till. Res. 37,211222.

    Alaoui, A., Lipiec, J., Gerke, H.H., 2011. A review of the changes in the soil poresystem due to soil deformation: a hydrodynamic perspective. Soil Till. Res.115, 115-116.

    Arthur, E., Schjnning, P., Moldrup, P., Tuller, M., de Jonge, L.W., 2013. Density andpermeability of a loess soil: long-term organic matter effect and the response tocompressive stress. Geoderma 236245, 193-194.

    Ball, B.C., 1981. Pore characteristics of soils from two cultivation experiments asshown by gas diffusivities and permeabilities and air-filled porosities. J. Soil Sci.32, 483498.

    Ball, B.C., Osullivan, M.F., Hunter, R., 1988. Gas diffusion, fluid flow and derived porecontinuity indices in relation to vehicle traffic and tillage. J. Soil. Sci. 39,327339.

    Berisso, F.E., Schjnning, P., Keller, T., Lamande, M., Etana, A., de Jonge, L.W., Iversen,B.V., Arvidsson, J., Forkman, J., 2012. Persistent effects of subsoil compaction onpore size distribution and gas transport in loamy soil. Soil Till. Res. 122, 4251.

    Blackwell, P.S., Ringrose-Voase, A.F., Jayawardane, N.S., Olsson, K.A., McKenzie, D.C.,Mason, W.K., 1990. The use of air-filled porosity and intrinsic permeability tocharacterize macropore structure and saturated hydraulic conductivity of claysoils. J. Soil Sci. 41, 215228.Please cite this article in press as: Kuncoro, P.H., et al., A study on the eII: Soil pore structure indices. Soil Tillage Res. (2014), http://dx.doi.Bormann, H., Klaassen, K., 2008. Seasonal and land use dependent variability of soilhydraulic and soil hydrological properties of two German soils. Geoderma 145,295302.

    Botta, G.F., Tolon Becerra, A., Bellora Melcon, F., 2009. Seedbed compactionproduced by traffic on four tillage regimes in the rolling Pampas of Argentina.Soil Till. Res. 105, 128134.

    Celik, I., Ortas, I., Kilic, S., 2004. Effects of compost, mycorrhiza, manure and fertilizeron some physical properties of a Chromoxerert soil. Soil Till. Res. 78, 5967.

    Dorner, J., Dec, D., Feest, E., Vasquez, N., Diaz, M., 2012. Dynamics of soil structureand pore functions of a volcanic ash soil under tillage. Soil Till. Res. 125, 5260.

    Dorner, J., Dec, D., Peng, X., Horn, R., 2010. Effect of land use change on the dynamicbehaviour of structural properties of an Andisol in southern Chile undersaturated and unsaturated hydraulic conditions. Geoderma 159, 189197.

    Dorner, J., Dec, D., Zuniga, F., Sandoval, P., Horn, R., 2011. Effect of land use change onAndosols pore functions and their functional resilience after mechanical andhydraulic stresses. Soil Till. Res. 7179, 115-116:.

    Dorner, J., Horn, R., 2006. Anisotropy of pore functions in structured stagnic Luvisolsin the Weichselian moraine region in N Germany. J. Plant Nutr. Soil Sci. 169,213220.

    Ellies, A., 1988. Mechanical consolidation in volcanic ash soils. In: Drescher, J., Horn,R., De Boodt, M. (Eds.), Impact of water and external forces on soil structure.Catena Verlag, Cremlingen-Destedt, W. Germany, ISSN 0722-0723 ISBN3-923381-11-5, pp. 8792.

    Fuentes, J.P., Flury, M., Bezdicek, D.F., 2004. Hydraulic properties in a silt loamsoil under natural prairie, conventional till and no till. Soil Sci. Soc. Am. J. 68,16791688.

    Gradwell, M.W., 1961. A laboratory study of the diffusion of oxygen through pasturetopsoils. N.Z. J. Sci. 4, 250270.

    Gregory, A., Watts Ch Griffiths, B., Hallett, P., Kuan, H., Whitmore, A., 2009. The effectof long-term soil management on the physical and biological resilience of arange of arable and grassland soils in England. Geoderma 153, 172185.

    Groenevelt, P.H., Kay, B.D., Grant, C.D., 1984. Physical assessment of a soil withrespect to rooting potential. Geoderma 34, 101114.

    Hamamoto, S., Perera, M.S.A., Resurreccion, A., Kawamoto, K., Hasegawa, S.,Komatsu, T., Moldrup, P., 2009. The solute diffusion coefficient in variablycompacted, unsaturated volcanic ash soils. Vadose Zone J. 8, 942952.

    Harris, W.L., 1971. The soil compaction process. In: Barnes, K.K., et al. (Eds.),Compaction of Agricultural Soils. American Society of Agricultural Engineers,Michigan, USA, pp. 944.

    Hassan, F.U., Ahmad, M., Ahmad, N., Kaleem Abbasi, M., 2007. Effects of subsoilcompaction on yield and yield attributes of wheat in the sub-humid region ofPakistan. Soil Till. Res. 96, 361366.

    Hillel, D., 1998. Environmental Soil Physics. Academic Press, CA.Iversen, B.V., Moldrup, P., Schjnning, P., Jacobsen, O.H., 2003. Field application of a

    portable air permeameter to characterize spatial variability in air and waterpermeability. Vadose Zone J. 2, 618626.

    Kuncoro, P.H., Koga, K., 2012. A simple and low cost method for measuring gasdiffusivity and air permeability over a single soil cylinder. J. Jpn. Soc. Soil Phys.120, 5560.

    Kuncoro, P.H., Koga, K., Satta, N., Muto, Y., 2014. A study on the effect of compactionon transport properties of soil gas and water. I: Gas diffusivity, air permeability,and saturated hydraulic conductivity. Soil Till. Res., submitted as accompanyingpaper.

    Kutlek, M., Jendele, L., Panayiotopoulos, K.P., 2006. The influence of uniaxialcompression upon pore size distribution in bi-modal soils. Soil Till. Res. 86,2737.

    Matthews, G.P., Laudone, G.M., Gregory, A.S., Bird, N.R.A., Matthews, A.G., de, G.,Whalley, W.R., 2010. Measurement and simulation of the effect of compaction onthe pore structure and saturated hydraulic conductivity of grassland and arablesoil. Water Resour. Res. 46 (5) , http://dx.doi.org/10.1029/2009WR007720.

    Mckibben, E.G., 1971. Introduction. In: Barnes, K.K. (Ed.), Compaction of AgriculturalSoils. American Society of Agricultural Engineers, Michigan, USA, pp. 36.

    Osunbitan, J.A., Oyedele, D.J., Adekalu, K.O., 2005. Tillage effects on bulk density,hydraulic conductivity and strength of a loamy sands oil in SouthwesternNigeria. Soil Till. Res. 82, 5764.

    Poulsen, T.G., Moldrup, P., Yamaguchi, T., Jacobsen, O.H., 1999. Predicting saturatedand unsaturated hydraulic conductivity in undisturbed soils from soil watercharacteristics. J. Soil Sci. 164, 877887.

    Resurreccion, A.C., Kawamoto, K., Komatsu, T., Moldrup, P., Sato, K., Rolston, D.E.,2007. Gas diffusivity and air permeability in a volcanic ash soil profile: effect oforganic matter and water retention. J. Soil Sci. 172 (6) 432443.

    Schjnning, P., 1989. Long-term reduced cultivation. II. Soil pore characteristics asshown by gas diffusivities and permeabilities and air-filled porosities. Soil Till.Res. 15, 91103.

    Schjnning, P., Christensen, B.T., Carstensen, B., 1994. Physical and chemical prop-erties of a sandy loam receiving animal manure, mineral fertilizer or nofertilizer for 90 years. Eur. J. Soil Sci. 45 (3) 257268.

    Schjnning, P., Iversen, B.V., Munkholm, L.J., Labouriau, R., Jacobsen, O.H., 2005. Porecharacteristics and hydraulic properties of a sandy loam supplied for a centurywith either animal manure or mineral fertilizers. Soil Use Manage. 21, 265275.

    Schjnning, P., Rasmussen, K.J., 2000. Soil strength and soil pore characteristics fordirect drilled and ploughed soils. Soil Till. Res. 57, 6982.

    Terzaghi, K., Peck, R.B., 1967. Soil mechanics in engineering practice, second ed.John Wiley and Sons, New York, NY.ffect of compaction on transport properties of soil gas and water.org/10.1016/j.still.2014.01.008

    http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0005http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0005http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0010http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0010http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0010http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0015http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0015http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0015http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0020http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0020http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0020http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0025http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0025http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0025http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0030http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0030http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0030http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0035http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0035http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0035http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0040http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0040http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0045http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0045http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0045http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0050http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0050http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0050http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0055http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0055http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0055http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0060http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0060http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0065http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0065http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0070http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0070http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0070http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0075http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0075http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0075http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0080http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0080http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0080http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0085http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0085http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0085http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0085http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0090http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0090http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0090http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0095http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0095http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0100http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0100http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0100http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0105http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0105http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0110http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0110http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0115http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0115http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0115http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0120http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0120http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0120http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0125http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0130http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0130http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0130http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0135http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0135http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0135http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0140http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0140http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0140http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0140http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0145http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0145http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0145http://dx.doi.org/10.1029/2009WR007720http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0155http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0155http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0160http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0160http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0160http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0165http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0165http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0165http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0170http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0170http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0175http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0175http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0175http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0180http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0180http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0180http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0185http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0185http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0185http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0190http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0190http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0195http://refhub.elsevier.com/S0167-1987(14)00015-4/sbref0195http://dx.doi.org/10.1016/j.still.2014.01.008

    A study on the effect of compaction on transport properties of soil gas and water. II: Soil pore structure indicesIntroductionMaterials and methodsPreparation of soil samplesOutline of measurementsDetermination of soil pore structure indicesStatistical analysis

    Results and discussionDry bulk density (d) and total porosity (f)Pore size distributionSpecific gas diffusivity (SD100)Specific air permeability (Ska100)Specific hydraulic conductivity (Sks)

    ConclusionsAcknowledgmentsReferences

Recommended

View more >