a study on the effect of compaction on transport properties of soil gas and water. ii: soil pore...

Soil & Tillage Research xxx (2014) xxx–xxx

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STILL-3255; No. of Pages 8

A 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 after

measurement of saturated hydraulic conductivity (ks). Corresponding dry bulk density (rd), total

porosity (f), and air content (e100) values were also determined. Volume of macropores (f � 30 mm) and

micropores (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 the

SD100 and Ska100, specific hydraulic conductivity (Sks) was defined as ks/e100. The results showed that

compaction significantly increased rd, which was followed by a reduction in f, and the mixed OM

resulted in a significantly lower rd and higher f than the control. The volume of macropores was reduced

by 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 acted

conversely. Discussion of the measured (Dp/D0)100, ka100, and ks is presented in the companion paper.

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1. 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: [email protected] (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 ¼Va

Vs(1)

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

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


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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 which

soil air and water may be transported.

Table 1Physical properties of the soil samples.

Organic matter content (%) 20.2

Gravimetric water content (g g�1) 0.70

Particle density (g cm�3) 2.52

Dry bulk density (g cm�3) 0.700

Texture: Sand [2–0.02 mm] (%) 72.5

Silt [0.02–0.002 mm] (%) 16.1

Clay [<0.002 mm] (%) 11.4

P.H. Kuncoro et al. / Soil & Tillage Research xxx (2014) xxx–xxx2

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directly evaluated by va. Conversely, ‘soil air content’ cannot bedirectly used because the total soil volume has changed.

The volume and arrangement (organization) of the soilmacropores are determinants of the state of soil air (e.g., Blackwellet al., 1990; Kuncoro et al., 2014; Schjønning et al., 2005) and water(e.g., Alaoui et al., 2011; Iversen et al., 2003; Kuncoro et al., 2014)being transported. We propose that the transport process may takeplace through pore arrangements ‘a’, ‘b’, and ‘c’ in Fig. 1 in whichgas diffusion is more affected by the ‘b’ arrangement, and either gasconvection or hydraulic conductivity (saturated) is more influ-enced by the ‘c’ arrangement compared with the ‘a’ arrangement.In the case of ‘d’ arrangement, it is considered inactive at high soilmatric potential (wetter conditions), but it may be open connectedat low soil matric potential (drier conditions) through which thesoil air can be transported. The transport process, however, doesnot occur for the dead-end or confined pores (‘e’ arrangement).

Soil compaction, besides obviously affecting the volume of soilpores and their size distribution, may alter the pore arrangement.The altered pore organization (pore continuity) has been shown toaffect gaseous transport (e.g., Arthur et al., 2013; Dorner et al.,2012; Schjønning and Rasmussen, 2000) and has been discussed toplay an important role in water transport (e.g. Bormann andKlaassen, 2008; Dorner et al., 2010; Osunbitan et al., 2005). Theindex of pore continuity is commonly determined from themeasured gaseous transport properties and air content (e.g.Blackwell et al., 1990; Dorner and Horn, 2006; Schjønning et al.,2005). In this study, we propose another index of pore continuitywhich is determined from the measured water transport propertyand volume of macropores. To our knowledge, there are only a fewstudies available concerned with the relationship between appliedorganic matter (OM) and pore continuity. Accordingly, this studyaimed to investigate the effects of compaction on selected porestructure indices of the OM-mixed soils, including total porosity,pore size distribution, and quantitative pore organization in termof both gaseous and water transport properties.

2. Materials and methods

2.1. Preparation of soil samples

As described in Kuncoro et al. (2014), disturbed sample of asandy loam volcanic ash soil (Table 1) taken from the ‘‘Takizawa’’experimental field of Iwate University in northern Japan waslightly sieved (4.76 mm) and set for 0.70 g g�1 in water content

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.

before it was mixed with rice husk, rice straw (cut into 2-cmlengths), wood bark compost (well decomposed), sawdust, andwood bark at 20% rate by volume. Typically, the rice husk was7 mm in length, sawdust was 0.5–2 mm granular, and wood barkwas 20–40, 3–5, and 0.5–1 mm in length, width, and thickness,respectively. Not different from the common andisols, the volcanicash soils in Japan are described having high content of OM and lowbulk density those can reach 17–27.5% and 0.51–0.60 g cm�3,respectively (e.g. Resurreccion et al., 2007; Hamamoto et al., 2009).

The mixed soil sample with OM was remolded in the followingmanner. A targeted 471 cm3 cylinder (10 cm wide and 6 cm long)was connected with two collars (each collar was 471 cm3 involume) at the both ends of this cylinder. The sample was filledthrough the upper one-third part of the lower collar, the targetedcylinder, and the lower one-third part of the upper collar. Thesample was then compressed by a prescribed static pressure fromthe upper and the lower side so that the friction between thesample and cylinder wall be minimized. The pressure was 150,225, and 300 kPa. Finally, excessive parts of the soil over the bothends of the targeted cylinder (471 cm3) were trimmed (Kuncoroet al., 2014). The static loads chosen were taken to emulate staticcompaction commonly occurring in agricultural fields by theoperation of farm machinery. Another repacked and compactedsample without any OM addition was used as a control.

2.2. Outline of measurements

The compacted soil samples were then preliminary saturatedwith water for measurement of saturated hydraulic conductivity(ks), which was conducted using the constant head method.Afterwards, consecutive measurements of relative gas diffusivity(Dp/D0)100 and air permeability (ka100) at �100 cm H2O soil matricsuction (soil pF 2.0) were conducted using a tool as described inKuncoro and Koga (2012) at a temperature of 20 8C. In thedetermination of the relative gas diffusivity, Dp was the gas diffusioncoefficient in soil and D0 was the gas diffusion coefficient in free air.

As a part of the companion study of Kuncoro et al. (2014), a setof soil pF tests were also conducted using the sand bed method forsoil pF 1.0 and 1.5, the hanging water column method for soil pF2.0, and the centrifugal method for soil pF 3.0 and 4.2. For each ofthese soil pF values, mass of the sample was measured todetermine the related water content.

Finally, the sample was oven dried at 105 8C for 24 h to deter-mine dry bulk density, from which total porosity (f) and air content(e) of each soil pF can be derived. For soil mixed with OM, the valueof f was determined in a four-phase soil system namely soilparticle, solid of OM, pore water, and air. All the measurementsabove were performed in triplicate using three soil samples foreach combination of compaction level and OM treatment.

Equivalent pore diameter of a certain volume of soil pores asrepresented by air content (e) at those soil pF was calculated usingthe theory of capillary rise after Terzaghi and Peck (1967) as in thefollowing equation:

hc ¼0:15

rcosa (2)

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


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

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where 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 Schjønning et al. (2005) as seen in the following equation:

Ska ¼ka

e(3)

in which Ska is specific air permeability (mm2), ka is air permeability(mm2), and e is air-filled porosity namely air content (cm3 cm�3).

The pore continuity index of soil may also be expressed in termsof 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;Schjønning, 1989; Schjønning et al., 2005). In this study, the indexwas termed ‘specific gas diffusivity’ as in Schjønning et al. (2005) asseen in the following equation:

SD ¼D p=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 ¼ks

e100(5)

where Sks is ‘specific hydraulic conductivity’ (cm s�1), ks issaturated hydraulic conductivity (cm s�1), and e100 is volume ofmacropores namely air content measured at �100 cm H2O soilmatric suction (cm3 cm�3).

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

ks ¼ 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 log–log graph of ks vs. fe (ks: fe characteristic), and

Table 2Arithmetic mean and standard deviation of dry bulk density (rd) and total porosity (f)

OM treatment rd (g cm�3)

150 kPa 225 kPa 300 kPa

Control 0.667 � 0.001 Ba 0.693 � 0.005 Ca 0.717 � 0.00

Rice husk 0.633 � 0.005 Bd 0.664 � 0.004 Cc 0.688 � 0.00

Rice straw 0.621 � 0.003 Bc 0.653 � 0.010 Cc 0.680 � 0.00

Compost 0.624 � 0.006 Bcd 0.654 � 0.006 Cc 0.687 � 0.01

Sawdust 0.604 � 0.007 Bb 0.632 � 0.006 Cb 0.661 � 0.00

Wood 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


therefore, expresses the sensitivity of ks with regard to fe. In a formanalogous to this concept, sensitivity of the measured Dp/D0 and ka

at �100 cm H2O soil matric suction as well as ks with regard to e100

in this study can be studied from the log–log 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 rd

or f even after the compaction took place. In accordance with thisresult, Celik et al. (2004) also reported a significant decrease in rd

and an increase in f within 0–30 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%. Schjønning et al. (2005) alsoobserved a significantly larger f (in average) of a loamy sand soilsupplied with animal manure for about a century (1.30–1.35% 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 cm�3)

150 kPa 225 kPa 300 kPa

5 Aa 0.735 � 0.000 Ab 0.725 � 0.002 Cb 0.715 � 0.002 Bb

2 Ad 0.744 � 0.002 Ac 0.732 � 0.002 Cc 0.722 � 0.001 Bab

8 Abd 0.750 � 0.001 Aa 0.737 � 0.004 Cac 0.726 � 0.003 Bac

2 Acd 0.745 � 0.002 Ac 0.732 � 0.002 Cc 0.719 � 0.005 Bbc

7 Ab 0.753 � 0.003 Aa 0.742 � 0.003 Ca 0.730 � 0.003 Ba

4 Abd 0.751 � 0.001 Aa 0.736 � 0.001 Cac 0.726 � 0.002 Bac

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



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 cm�3) [f � 30 mm] nw100 (cm3 cm�3) [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 Aa

Rice 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 Aa

Rice 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 Aa

Compost 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 Aa

Sawdust 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 Aa

Wood 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).


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volume 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 Kutıleket 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 20–50 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, silty

Table 4Effect of compaction on distribution of macro and micro-pores as indicated by air cont

respectively.

OM treatment e100 (cm3 cm�3) [f � 30 mm]

150 kPa 225 kPa 300 kPa

Control 0.186 � 0.003 Ab 0.160 � 0.013 Cbd 0.128 � 0.0

Rice husk 0.230 � 0.016 Aa 0.191 � 0.012 Bac 0.156 � 0.0

Rice straw 0.198 � 0.014 Aab 0.164 � 0.013 Cbc 0.119 � 0.0

Compost 0.183 � 0.011 Ab 0.151 � 0.011 ABb 0.106 � 0.0

Sawdust 0.227 � 0.019 Aa 0.205 � 0.010 Aa 0.160 � 0.0

Wood 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


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 1.4–1.6%).In their study, however, the volume of macropores (f > 4.5 mm)was also observed to significantly increase. Similarly, Schjønninget al. (1994) and Schjønning et al. (2005) reported a significantlylarger volume of micropores (f < 30 mm) in soil dressed withanimal manure (1.32% and 1.30–1.35% in OM content, respective-ly) than in soil dressed with inorganic fertilizers (1.19% and 1.15–1.25% 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, 300–95 mm,95–30 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 <0.2 mm and 0.2–3.0 mm, whereas a slight

ent (e100) and volumetric water content (u100) at �100 cm H2O soil matric suction,

u100 (cm3 cm�3) [f < 30 mm]

150 kPa 225 kPa 300 kPa

09 Bab 0.549 � 0.002 Bac 0.565 � 0.011 Bab 0.587 � 0.009 Aa

18 Ba 0.514 � 0.013 Bb 0.541 � 0.012 ABb 0.566 � 0.018 Aa

07 Bab 0.552 � 0.015 Bac 0.574 � 0.014 Bac 0.608 � 0.008 Aa

30 Bb 0.561 � 0.012 Aa 0.582 � 0.012 Aa 0.612 � 0.035Aa

12 Ba 0.526 � 0.016 Bbc 0.537 � 0.008 Bb 0.570 � 0.010 Aa

11 Ba 0.521 � 0.010 Bbc 0.547 � 0.005 Abc 0.567 � 0.010 Aa

r (column), are not significantly different (P < 0.05).



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 treatment

followed by same letter are not significantly different (P < 0.05).(D

p /D

0)10

0

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 soil

matric suction (Dp/D0)100 with regard to the corresponding air content (e100) (**

P < 0.01).


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change 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 bySchjønning and Rasmussen (2000) after compaction with directdrilling using a triple-disc drill on a coarse sandy soil at 4–8 and14–18 cm depth and for a loamy sand soil at 4–8 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.


This result, however, was different from Schjønning 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 (1.15–1.35% 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-mixed



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 bark

a

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 treatment

followed by same letter are not significantly different (P < 0.05).


G Model


soils 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 loam–silty 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. Schjønning 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 the


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 Schjønning et al. (2005)after their study on a loamy sand soil dressed with animal manureand mineral fertilizer for about a century (1.15–1.35% 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 (1.53–2.37% 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 Schjønning 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.



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 matric

suction (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 volume

of macropores (e100) (** P < 0.01).


G Model


3.5. 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 was

0

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0.005

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150 kPa 225 kPa 300 kPa

Control

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bb

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0.002

0.003

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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 compactions

are not significantly different (P < 0.05).


also 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 of‘‘ceramic 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 was

225 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




G Model


probably 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, 113–120.

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, 699–702.

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. 37,211–222.

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.1–15, 115-116.

Arthur, E., Schjønning, 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 236–245, 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, 483–498.

Ball, B.C., O’sullivan, M.F., Hunter, R., 1988. Gas diffusion, fluid flow and derived porecontinuity indices in relation to vehicle traffic and tillage. J. Soil. Sci. 39,327–339.

Berisso, F.E., Schjønning, 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, 42–51.

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, 215–228.


Bormann, H., Klaassen, K., 2008. Seasonal and land use dependent variability of soilhydraulic and soil hydrological properties of two German soils. Geoderma 145,295–302.

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, 128–134.

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, 59–67.

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, 52–60.

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, 189–197.

Dorner, J., Dec, D., Zuniga, F., Sandoval, P., Horn, R., 2011. Effect of land use change onAndosol’s pore functions and their functional resilience after mechanical andhydraulic stresses. Soil Till. Res. 71–79, 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. 169,213–220.

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. 87–92.

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. 68,1679–1688.

Gradwell, M.W., 1961. A laboratory study of the diffusion of oxygen through pasturetopsoils. N.Z. J. Sci. 4, 250–270.

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, 172–185.

Groenevelt, P.H., Kay, B.D., Grant, C.D., 1984. Physical assessment of a soil withrespect to rooting potential. Geoderma 34, 101–114.

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, 942–952.

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. 9–44.

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, 361–366.

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

portable air permeameter to characterize spatial variability in air and waterpermeability. Vadose Zone J. 2, 618–626.

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, 55–60.

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.

Kutılek, M., Jendele, L., Panayiotopoulos, K.P., 2006. The influence of uniaxialcompression upon pore size distribution in bi-modal soils. Soil Till. Res. 86,27–37.

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. 3–6.

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, 57–64.

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, 877–887.

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) 432–443.

Schjønning, P., 1989. Long-term reduced cultivation. II. Soil pore characteristics asshown by gas diffusivities and permeabilities and air-filled porosities. Soil Till.Res. 15, 91–103.

Schjønning, 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) 257–268.

Schjønning, 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, 265–275.

Schjønning, P., Rasmussen, K.J., 2000. Soil strength and soil pore characteristics fordirect drilled and ploughed soils. Soil Till. Res. 57, 69–82.

Terzaghi, K., Peck, R.B., 1967. Soil mechanics in engineering practice, second ed.John Wiley and Sons, New York, NY.


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