
J. Jpn. Soc. Soil Phys.
¨©oNo. +*., p. /+ 0* ,**0Profile Probe 



  *ῌ**ῌ

**, ***ῌ*, ****ῌ *

Monitoring Soil Water Content for Kuroboku and Tachikawa-Loam Soils with
Proﬁle Probe type PR+ : Laboratory Calibration and Field Tests
Hiromi IMOTO*, Akihiko KAMOSHITA**, Yoichiro KATO**, ***,
Takeshi TOKIDA**, **** and Tsuyoshi MIYAZAKI** Department of Biological and Environmental Engineering, Graduate School of
Agricultural and Life Sciences, The University of Tokyo** Field Production Science Center, Graduate School of Agricultural andLife Sciences, The University of Tokyo***, **** JSPS Research Fellow
Abstract
In order to understand the soil moisture conditions in ﬁelds, many soil moisture sensors havebeen developed in recent years.

In this study, the range of inﬂuence of Proﬁle Probe type PR+ soil

moisture sensor (hereafter referred to as “PR+”, Delta-T Devices, Ltd) was measured and speciﬁccalibration equations were established for Kuroboku and Tachikawa Loam soils. The range ofinﬂuence of PR+ was estimated to be +* cm in both horizontal and vertical directions. Standard
calibration equations (“Mineral equation”, proposed for mineral soil and the “Organic equation”,
proposed for organic-matter rich soil) provided by the manufacturer were found to be invalid for
Kuroboku soil. For Tachikawa Loam soil, the Mineral equation was found to be applicable. For
precise water content determinations, however, we found that speciﬁc calibrations for each of thePR+ sensor may be required.

A long-term ﬁeld measurement indicates that PR+ may be a usefuldevice for proﬁling soil water content and measuring changes in water content after rainfall
events.
Key words : Proﬁle Probe, soil moisture sensor, calibration, Kuroboku soil, Tachikawa Loam+      !"#$%&'() *+Delta-T Devices TUVW[)*\[;AG0;]& Profile Probe 04^5678&9 _V `,**,a W
Bb/cKdAef gZXY TDR ,-./ CS0+/,-./012)345678&9 :) `Campbell Ta ECH,O, h/cijkl/H mn&,

;<=>?@A .-BC-DEFEA-./:op8"qrL'9 s `,**-a WtZGH"IJKL',-./0MN5678&9 'KO

d BbuvwidH 1 xy,-./"z8

P Q R S - T U V W X Y Z  ECH,O Probe 0{6V,-./"z8&K])W|)}&~0*   ++-ῌ20/1  +ῌ+ῌ+**   +22ῌ***, M +ῌ+ῌ+*** : DC ` a**** : DC ` a : BbuvwiBb/c ,-./ Cc/ ¡- ¢£¤ ¥¦b/§; ¼ +*. ^ ,**052 

)*g*H , ~6&*|'g TDR(  P8 IJ W !"# $(g:;<*V {L ,**-


TDR %& ,***a'()* TDRK; 7'

)+,-./ -0120.3 +/*,B  4

*g{5067'8 ¥w,(¦*-  {@* + ¡* ¢£,¤Delta-T 39 Proﬁle Probe PR+ :;<m!"{ 76 :;<LK

=> PR+ ?@;§.*8C ,/ mm

 Fig. + a A@B

D /W LK

; 7'K¨,*8

D +** cm =EFG**H{I

IJ .-;K.9:;<L;M + NOP

PR+   . &©

.W  0 &© 0

QRRSHT U V W W gVg +)*0W © |D +* ,** -* .* 0* +** cm 

Fig. +aX I Y0:.

Z[\ +** MHz ]^_ `_DW
ab@ Gaskin and Miller +330,ῌ ῑ῔῍῏῎ῑῐΐH Y0:.Z[cdef

0ª«¬1¬­2®¬ ¡®3¯41'.6abg_DW* Wdhi<;L;M LK;°± jklm n:;<L;Mf '*768

LK;opq _brsJt HH, uv

5 450  IB²³ 6&´

w/rsBxyDW  WB8  8z{|D} dhi  3 · / 8$*g*H: 8~ TDR  ECH,O Probe   PR+ _@!"g{Q + 8 + ¸ ¹9+

PR+ :;<¢£,¤º

WµW,**, 7 2 · ++ 8

 m#$%ῒῌ+Fig. +

7'*¶Q»

Schematic diagram showing how to determine the range of inﬂuence of PR+ sensor.

µ¶·¸ : Profile Probe--+ 

A¹ºJ;0»R¼9"; *  !" H

PR+ 
  

f9;+.' _ O8[  9P s 9

y'



    !"#$ % & '() *+,

- -* cm, .' +,* cm, / + cm 012345
8 9:;<=:#$ %>? @  ABCD@ 5 99 E FG9;

H IJKLM <= ?N O8*P

PR+ QRS?'( IJKLM

5TUPVW:TXY[ TU\ 61]3 7
 `+;Z'(

^8_abcdB ^+  +A5#$

e fA ghT CD

AB 9:#$

%

i



y',_ cd 9-y' +* cm ; ,KQHf9;+.';4,) ++, 0 )H ,*cm 

8CD @  -, 



Fig. , 6a7

PR+_e9 Z'( D@¡35; PR+\,) PR+ TUh8p ¢8 _[ £¤ ' / cm h;FG¥  '+* cm h;+N,F;¦f$r

p  6Fig.

, 6a77  9P,)h§ TU +* cm >hh§#$ .¨,©+;ªT
Fig. , 6b7@ <=: ^~#$ %

¡9-y',)

^« 9?

) -* cm _q¬s@

6b7 <=:#$ %j- / 1 +* +- +/ cm ; *hh9-

q+; 

6a7 9:#$ %Fig. + 6a7

 +4,KK, 9AB )

PR+ 

6Fig. + 6a7753

 klmn ! +;op !

9""#q<=:$r

 *s PR+ 

,tuv9wxq y':%z$) 9-y * cm ,);© _e .*.* mV ,) ­®P,/Uh_e-..1]-2.* mV ;FG+e,) 6Fig. , 6b77 *

r 6klmn{9"$r7 #$ |p}~&

 PR+.8 9:~, p <=:#$°; _e .2.].3* mV ; B $r±U% CD+;q ,)<=:#$

%

h

9

j

 PR+p

[ ?S'( 9-y +* cm¯ +;© sTU9-8 -*cm @_e;qj² >

[ 9P s+; ACD PR+  +TU <=:#$ %KQ³´;+ +* cm ,)+;ªT' +* cm (,',?

KQ)s!h8 6Fig. + 6b77 ++,?KQ

*



)

ῌ,
Fig. ,

PR+ #$%Range of inﬂuence of PR+ sensor.

!  +*.  ,**0

54.  PR+  .+ 

 Fig.

-   *.* cm    .*+** cm!"#$%&Q , !

RS1TU@?VC?W2 , mm X1Y

Z2MRS1ABCDE%FG?[

2\2M

>?@%]^_`!abcde) fghi'jk


ABCDE%FG?1HIJK8( L!MN OP'() +** cm *+,'-.

/ , !01/2
92:;/!' <34536/78
=2 PR+ >?@%!

ῌFig. -+* cm lm nohi'p+ +* cm lm!

RS8

JK'(O 8qrsM!' Fig. . !eI/ tk-* cm, *+ -* cm, up + cm !vwx!3yz{|}&1[ABCDE%FG?1HsM z{|}&!
~k ,.2 cm !>

ABCDE%FG?[RS!

Proﬁle of physical properties of soil used for calibration.

ῌ.

PR+ ABCDE%FG?[|}&

Fig. .

Schematic of calibration box.

%D1b2Mº»¼/¤ : Profile Probe JH()*  -./ PR+ 







   / mm : 

55

F ' +  +  9/ 0 ZH +' 9/\   !" #$%&' ()* +`=kGHJ[' PR+*.0* g cm,-'

/ LM > ' +,*-./+ *./ g cm,- +01

23456/789' %' > ?@A =%&>E' 

 PR+

F

:

;<

=

BC  D
GHIJKLM

 NOPQRST UG
ῌ ()*  -./῏:%\e'  i'' >VWV 

#$%HI+' ., 

: _ `\ / cm RHJ[

Rab cdR\efeg  OJi + jk D,.

j

¡¢

-./

]H(|)\CR]¬rfe 

H Organic ­ D

=%& :  BC=%R\eyvzGH' r{|+ }M῎JH :  BC' ~ +HIJM& w PR+F  ! +: !"abj &'
=% uJ PR+

ῌ/Fig. /()*']23456/789-./ §¨+H Delta-T ©feª«=V&
Mineral ­ DF s tM Ru' +vHw x

 & 

Fig. /' 0 UG .£¤ ¥()* ' ¦  lRGE I ab mnop&' Nq
PR+ LM  &feBC

()* 'K \heg

./5JK : Kw'  &' !"

 \VR]J[^ ]
01?'

: 

O"=%' 9#=%& - F $lMX= ,/ cm Y+Z  RHJ[01 
῍

PR+

T©

:*z#[]$VH

E' (|)\] :*z#[]$VE ®¯U ()* + Delta-

Mineral ­' Organic ­ °±e®§¨²

RfM\'-./ + Mineral ­\§¨

fRK³fM]V®

&\X]´°Fµ¨\XfM

 f' ()* + & /*ῌ N'+ 1*ῌ NRHuH PR+ 9/-./

&XzRH¶·¸¹

Calibration curve for PR+ output (mV) vs. volumetric water content (ῌ) for Kuroboku soil.

F:'G¶ » +*. ¼ A,**0B

56  / 

  
  ! " # $%&'/+ ( )*+,-'./0()123" 4  5( ).* +,)_-./_6 '8)9*ῌ )"7'./" :;<56=>+( Fig. 1 7T=j7 .- m S +, 7
0'1*(" 8 .2$

 '?@39" A ,**/B 83'1

3[ 1453

*CDED$%&7F *GH'IJKLMNB ) B A6!B ' 7 87$%&)z(* PR+ nRDe'9

O

7PQRMSD$%&'T

 $%&PRMSD7U "VW)

2

 + 6 + y7z8 (X .** mV Y +* cm RMSD)

 0*ῌ )Z[" ,* cm RMSD'z8/*ῌ )Z[AFig. 0B   * '\] A A#

+

PR+ H:¡!$7;,**, < 2 ¢ ++ 6 £3 ¢ / 6 + ¤¢¥H 0¦>§>¨¥'z( , ¤¢ ++ ¢ 1 67 ©=nRDe7 PR+

%^7H"9"_`7 0 ]RM'-ª«:'H

SDa7]*bcdefDghM'ij(*nRDe7>¬9"8)

AbBB ¯[@°7 +** cm 4 +** cc ±SMr²D

k lmn TDR op& AqKr&B )s ()t*!

Au3 A+332B  v A,***bB w! A,**.BB xy PR+ 7z(*+ Organic &G

H=> '{ "|*(AFig. /B #v}D~ Mineral &$% s  &'&$ #)123"ῌ0Fig. 08)! 77z­®'?> AFig. 1

A³B:SMrdMN'i( C´D 'µ# ) PR+ H)'i7

7z":EF)'G¶' Fig. 1 AaB 7T
/,

Fig. 2 7 A, B  PR+ H«§>)·¸'T H¨¥ + ¤¢)I¨¥9 ·¸7=#v}D~7z"P PR+ RMSD$%¹ºCalibration curve for PR+ output (mV) vs. volumetric water content (ῌ) for Tachikawa Loam.

¡¢£  : Profile Probe +* ,* -* cm N%`abc"def gcUl¤ 

57

 m$= /no & !<0 def gp   !" #$%&

q Y`abcr4Z'()*+,-./012  34 & 

67@ABxyq"z{<*% j"|};0* cm5+** cm /0'(67089:;<)$=
  .* cm 0 +* cm5-* cm >?/0)* '(67@AB CD &`abcU stuvw<%& ?~; *5.* cm /,*5.*ῌ "3  .* cm /0 0*52*ῌ "w )=* & .* cm /qp"4qpUS

EFGHI JKLM N=O;< PQR/S

 & !<0q`abc"4qdef gUT UV@ WX A YFig. 3 YaZZ WX B-.*@N*%& 9  qp Y *5[*\<]<^_& `abc de.* cmZ /) :;<%  '("YFig. 3 YbZZ

fgchi .* cm

Mineral R@80j:[*0 Organic R

+, N%67/S 

Organic Rk%& !N)S .* cm 9//8 .* cm 

ῌῌ1Fig. 1

Go"c

Location of sampling pits and soil physical properties.

ῌῌ2
Fig. 2Ll

PR+ S Y,**,  2  ++53  /Z

Changes in PR+ output at various depths (++ August to / September, ,**,).

j"|};<

:; ¹ºi » +*. ¼ O,**0P

58



z" n'*JKL',

PR+  ῍ !" #$%&

ῌ{|`}`Lr , ~Ag &'()*+', -'./012345 6

lm A B h PR+ *.V"_,:;

78"%9:;*<=>? @A%BC
DE%FGH",I*JKL', MN O,**.P
QRS O,***bP ?'T TDR  "UVW45
XY8 ZL[\ :; ]^"_`- _a@A

O῏ P



  OFig. +*P .V

p q   ῍    PR +G

OMineral U_ Organic P "_,pq῍ O*o.* cm  Organic 

0* cm  Mineral P%BC b'%#$cd*,-*efg, N

04*"& :;IG OFig.

 hT./012345*:;* <=i"9jk/g% lm A

0P " ¡¢gpq῍h£, ¤¥¦§

n -*o.* cm "U pq῍gG"_,¨¢pq῍%©!*ª«¬g

OqP %r +2ῌ Lr .*ῌ *s\tuvg OFig. 3

 ­®U_ 2* cm h¯° ?'%±

OaPP .* cm n"U./012345*:;*L'% -'­®h./012345*:;<=i%9ht w῎DE)+xpq῍%y²³%F9´µ¶i%  2* cm h

ῌῌ3Fig. 3

PR+ 04LIpq῍· O,**,. 2o,**,. 3P

Vertical distribution of soil water content determined by PR+ (++ August to / September, ,**,).

ῌῌ+*
Fig. +*

PR+ U_῏

"_,¸:;pq῍©! O,**,. ++. 1P

Depth proﬁle of soil water content as determined by PR+ and the gravimetric method atupland ﬁeld (1 November ,**,).

vw¼f : Profile Probe g$ab 

ῌ+ #$%&'(Table +

PR+  01

E#ect of void space around the access tube on PR+ outputs
Output (mV)
-31
-33
-31
»

,* cm ¹º89[;
HBC J

-0*
-1+
-03
-0/

@

-32

@

-00

 Fig. / 0 

 +* cm z& }WUa6M +* cm z&X~"K+Y)-  


Output (mV),* cm ¹º89[;
HBCEJ


59

!

EF>

)*! c|[ %UqL
CZ[;\EF-]" >

/- 
PR+   "#$%&'(

,J

+* cm

F %Uq-

PR+ ]M)*!

* 0 L+L* )* + ,-M  ^+-:_`;" 0 L/

. /01-2*!   #$%&'(3 _`-<=F+,"> 6

-456-7)*89:; /97 !

 -<=*>? @ -32 mV  )*!

#$%&'(A!"BC 9*#D$EF #$%&'(C%G&'(-Jg$ abL" PR+ _c- |<=*!
.J

Z#R>

xy jkd

H&I +.. mm, AI ,.2 mmJ K'-LMN -e fgh i- =*>? @L -00 mV )* HTable +J! B

9*!

C (O*9 )P *MQ)*>  #$%&'(C

RSTU (O*5;  )P *MQ+, V*WM

>

.M

*! >>

/J

Z# PR+ -J" #$%&'(j

 #$%

&'(/L0123X-Y; #$%&'( 4"5 ;67
>)*! 8 Z#L [9\X-]

n<<o(pvwqrsto#uUqa *= 4=b-7"!

6Q~b-;"!

c >;?\F#$%&'(@L

E<ic|})*! >>   dSTU-"  M eTfgfhABCi

0

v wxyz¡ ¢b wz¡ £¤{ wz¡L

[^FQ:;9LX_I <9Q`jk DE-l Fm> GE!

 $hkbl-mE*!

Gaskin, G. J. and Miller, J.D. (+330) : Measurement ofsoil water content using a simpliﬁed impedance 

measuring technique. Journal of Agricultural

Delta-T HI Proﬁle Probe PR+ Engineering Research, 0- : +/-ῌ+0*.

-J -K+EF LMGC"no-¥¦§ H,**-J : Y)¨p= -K+E*dSq(rst-.)
*! >
ST-

NOuP-QFZ# HR>J E*! 'vwxy z[N{



)*!
+J

PR+ L |cF UaVI©ª"«01 ¬ ./ ­s®¯°7± .*ῌ.+.
'²³ῌ


´ῌZῌ¥¦§ H,**,J : c;| TDR Cµ o¶{¬ +. <¬·¸7± ,1.ῌ » +*. ¼ ,**0

60

,1/.

+/.

 ,**- :  TDR

ῌ

 3- : /1ῌ0/.

 ,**/ : ,* GHz-TDR >?@AῌBCDEFῌGHIJῌHKLM +332 :NOPQRST UVWX TDR!"#$%&'

() *+,- .. : 31ῌ+*,.

!"#Y8

Z[\ῌ]^_ `a bc-de
03 : 0--ῌ0-/.

./012 ,***a : 345 6789:;

fagh ,**. : TDR

UiX < jk

lm .2 : +1ῌ,,.

 2- : .+ῌ.0.
./012 ,***b : TDR < 78=  -, : +*ῌ῍ῌ

no 78p q; rstX#uU Cv wxyz{|}~X
aZ  Profile Probe
345 =0z

wxyz PR+ U wxyz  PR+ zx "# 78UV PR+. "# wxyz Z +* cm, Z +* cm = "# 345 Z
Delta-T ¡¢£X Mineral ¤ ¥¦§ ¨© Uª  Organic ¤ ¥¦©{C

Uª  =«U2¬ ­"# 0z Z

Mineral ¤{®=n­"# PR+ 

wxyz¯°±¤²³ ´µ­U# 78UV« ¶·UiX=¸{
~#
¹ºok` : ,**0 o 1 k ,. `¹ok` : ,**0 o 3 k +3 `