"#$%&'()*+,-./0, "1
Soil colloids
1*/. 2*..*/34 ,+5 675 8*46 2758/2,..9 ,2:;5 <+,2:*0 *< 4*/.4 =/67 ;5+9 48,.. 4/-5> .544 67,0 & ?8 /0 3/,8565+@ • A52,B45 *< 675/+ 48,.. 4/-5> ,.. 4*/. 2*..*/34 5CD*45 , .,+E5 5C65+0,. 4B+<,25 ,+5, D5+ B0/6 8,44@ • 1*/. 2*..*/34 2,0 ,F+,26 ,03 7*.3 D*4/:;5.9 27,+E53 /*04 3B5 6* 675/+ .,+E5 4B+<,25 ,+5, ,03 05E,:;5 27,+E54@ • G7/4 27,+,265+/4:2 /4 /8D*+6,06 H52,B45 8,09 D*4/:;5.9 27,+E53 /*04 ,+5 D.,06 0B6+/5064@ •
Soil colloids
1*/. 2*..*/34 ,+5 675 8*46 2758/2,..9 ,2:;5 <+,2:*0 *< 4*/.4 =/67 ;5+9 48,.. 4/-5> .544 67,0 & ?8 /0 3/,8565+@ • A52,B45 *< 675/+ 48,.. 4/-5> ,.. 4*/. 2*..*/34 5CD*45 , .,+E5 5C65+0,. 4B+<,25 ,+5, D5+ B0/6 8,44@ • 1*/. 2*..*/34 2,0 ,F+,26 ,03 7*.3 D*4/:;5.9 27,+E53 /*04 3B5 6* 675/+ .,+E5 4B+<,25 ,+5, ,03 05E,:;5 27,+E54@ • G7/4 27,+,265+/4:2 /4 /8D*+6,06 H52,B45 8,09 D*4/:;5.9 27,+E53 /*04 ,+5 D.,06 0B6+/5064@ •
Soil colloids
Crystalline silicate clay
Iron and aluminum oxide
!"#$% '( %')* +'**'),%
Non-crystalline silicate clay
Organic (Humus)
Silicate clay (crystalline and non-crystalline)
1/./2,65 2.,9 2*04/464 8,/0.9 *< :E76.9 H*0353> 4/./2*0 ,03 *C9E50 ,6*84@ • G75 3/I5+50254 H56=550 2+946,../05 ,03 0*0J2+946,../05 4/./2,65 2.,9 /4 675 ,++,0E58506 *< 47556K • L+946,../05 4/./2,65 2.,9M 675/+ 2+946,../05 46+B26B+5 /4 .,95+53 ./N5 D,E54 /0 H**N OP/EB+5 ,Q@ • )*0J2+946,../05 4/./2,65 2.,9M 3* 0*6 5C7/H/6 *+35+53> 2+946,../05 47556 OP/EB+5 HQ@ •
a
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b
Basic units of silicate clay •
1/./2,65 2.,9 8/05+,. 2*8D*453 *< 6=* N/034 *
b
-)*)+'. !$/012$,01* 34 -)5 6 78
9*:;).):;<;1=.$%):; 7+/12$,01*34 9*>?=5 @ 7>7A8
Basic units of silicate clay: Sheets
G75 H,4/2 8*.52B.,+ ,03 46+B26B+,. 2*8D*0506 *< 4/./2,65 2.,9@ O,Q " 4/0E.5 656+,753+*0> 2*8D*453 *< , 1/ /*0 4B++*B0353 H9 <*B+ T& ,6*8M ,03 , 4/0E.5 *26,753+*0> /0 =7/27 ,0 ". O*+ UEQ /*0 /4 4B++*B0353 H9 4/C 793+*C9 E+*BD4 *+ T& ,6*84@ OHQ S0 2.,9 2+946,.4 67*B4,034 *< 67545
Basic units of silicate clay: Combined sheets
4B4
C'.< $D#1.,).=
E1'*).)/$5 !"##$%&'() -;$+H/$ 3?'.;'0)**'.)/$8
!"#$ '( %)*)+1/$ +*1"
GD#1.,).= I$0;)+:*)/$ FB4 C'.< $D#1.,).=
J).$<=01).$, ;)+1> K**)/$ L2*'0)/$
Basic units of silicate clay: Combined sheets
12758,:2 3+,=/0E /..B46+,:0E 675 *+E,0/-,:*0 *< 656+,753+,. ,03 *26,753+,. 475564 /0 *05 'K'J69D5 8/05+,. ON,*./0/65Q ,03 <*B+ &K'J69D5 8/05+,.4@
Charges of colloids
V W5+8,0506 27,+E54 • G7+*BE7 /4*8*+D7*B4 4BH4:6B:*0 • U*46.9 /0 &K' 4/./2,65 2.,94 X G58D*+,+9 27,+E54 • G7+*BE7 DY 35D503506 • Z5D503 *0 4*/. DY • S0 'K' 2.,94 ON,*./0/65Q> 7B8B4> ,..*D7,05 ,03 P5[". *C/354 • L7,+E5 +5.,653 6* TYJ E+*BD@
Isomorphous substitution • K%';'0#2':% %:M%H/:H'.K 675 +5D.,258506 *< *05 ,6*8 H9 ,0*675+
=/67*B6 *< 4/8/.,+ 4/-5 /0 , 2+946,. .,\25 =/67*B6 3/4+BD:0E *+ 27,0E/0E 675 2+946,. 46+B26B+5 *< 675 8/05+,. O2,:*0 +5D.,258506 /0 8/05+,.4Q@ • R0*=0 ,4 D5+8,0506 27,+E5 ,03 B0,I52653 H9 4*.B:*0 DY@ • U,]*+ 4*B+25 *< ^;5 27,+E5K +5D.,258506 *< 656+,753+,. 1/ _` ,03 *26,753+,. "._a 2,:*04 =/67 2,:*04 *< .*=5+ 27,+E5@ Substitution of Al3+ with Mg2+ formed one net –ve charge at exchange sites.
• •
W+53*8/0,65.9 /0 675 &K' 8/05+,.4@ T22B+ 3B+/0E 675 <*+8,:*0 *< 67545 8/05+,.4 ,03 B0,I52653 H9 D+54506 50;/+*08506,. 2*03/:*04@
pH dependent • • • • • • •
152*03 4*B+25 *< 27,+E54 /4 ,44*2/,653 =/67 53E5 27,+E5 *< 675 2.,9 8/05+,.4@ G75 bB,0:69 *< ^;5 ,03 _;5 27,+E5 *0 675 53E54 35D5034 *0 4*/. 4*.B:*0 DY@ G5+853 ,4 ;,+/,H.5 *+ DYJ35D503506@ c035+ .*= DY> 675 53E5 /4 _;5 H52,B45 *< 675 5C2544 Y _ /*04 ,44*2/,653 =/67 675 5CD*453 1/JTY ,03 ".JTY E+*BD4@ "4 4*/. 4*.B:*0 DY /02+5,454> 4*85 *< 675 Y_ /4 05B6+,./-53 ,03 675 OJ;5Q 53E5 27,+E5 /02+5,454@ S02+5,4/0E 675 DY ,H*;5 d@e> 2*8D.565 +58*;,. *< Y_ /*04 *0 675 1/JTY ,03 ".JTY E+*BD4> =7/27 /4 8,C/8/-54 675 OJ;5Q 53E5 27,+E5@ 1*/. TU /4 4*B+25 *< DY 35D503506 27,+E5 =/67 675 3/44*2/,:*0 *< Y _ <+*8 2,+H*C9./2 ,2/34 ,03 D750*./2 ,2/34 E+*BD4@ "4 DY /02+5,454> 4*85 *< 67545 /*0 Y_ 05B6+,./-5 ,03 /02+5,4/0E 675 OJ;5Q 4B+<,25 27,+E5@
1:1-type silicate clay
Adjoining sheet
'K'> /03/2,65M ' 1/./2*0 656+,753+,. ,03 ' ,.B8/0/B8 *26,753+,. 47556 O<*+ 5,27 .,95+Q@ • fC,8D.5K R,*./0/65> !"##$%&'()* ,"-.'() ,03 /'-0'()1 • G75 6=* 69D54 *< 47556 ,+5 :E76.9 75.3 6*E5675+ H52,B45 675 ,D/2,. T ,6*8 /0 5,27 656+,753+*0 ,.4* <*+84 675 H*F*8 2*+05+ *< *05 *+ 8*+5 *26,753+*04 /0 675 ,3]*/0/0E 47556@ •
1:1-type silicate clay Layer 1
Y93+*C9. D.,05 /4 5CD*453K ! +58*;,.[,33/:*0,. *< Y_ 2,0 D+*3B25 _ *+ ^ 27,+E54 35D503/0E *0 675 4*/. DY@ ! ".4* H/034 =/67 ,0/*04@ •
g750 675 475564 ,+5 46,2N53 *0 6*D *< *05 ,0*675+> 675 ,3],2506 .,95+4 ,+5 H*B03 6*E5675+ H9 793+*E50 H*03/0E@ • 16+*0E 793+*E50 H*03/0E +54B.64 0* 4=5../0E /0 N,*./0/654 O0*0J5CD,03/0E Layer 2 Hydrogen bonding ,3],2506 .,95+Q@ • R,*./0/65 5C7/H/6 .544 D.,4:2/69> 4:2N/0544> 2*754/*0> 47+/0N,E5> 4=5../0E ,03 7*.3 G75 TYJ *< 675 *26,753+,. 475564 /0 .544 =,65+ 67,0 *675+ 2.,94@ .,95+ & ,+5 ,3],2506 6* 675 H,4,. T J *< 675 656+,753+,. 47556 *< .,95+ '> =7/27 • 'K' 2.,94 ,+5 5,49 6* 2B.:;,65 <*+ <*+8 793+*E50 H*03/0E H56=550 67545 ,E+/2B.6B+5 ,03 4B/6,H.5 <*+ +*,3H53 ,03 6=* .,95+4 O,6 /065+.,95+Q@ HB/.3/0E <*B03,:*04@ •
2:1-type silicate clay (expanding) f,27 .,95+ 2*06,/04 ' *26,753+,. 47556 4,03=/2753 H56=550 & 656+,753+,. 475564
+ 5 9 , . + 5 6 0 S
2:1-type silicate clay (expanding: Smectite group ) 1852:654 7;5 , &K' 46+B26B+5 67,6 5CD*454 , .,95+ *< T ,6*84 ,6 H*67 675 6*D ,03 H*F*8 D.,05 67,6 2*06+/HB654 6* 675 .**45.9 H*B03 ,6 /065+.,95+ O;5+9 =5,N TKT ,03 TK2,:*0 ./0N,E5 H56=550 & .,95+4Q@ • L*88*0 4852:65K U*068*+/..*0/65@ • S065+.,95+ 5CD,04/*0 *22B+4 ,4 Y&T h..4 4D,254 H56=550 .,95+ /0 3+9 2.,9@ • Y,;5 , 7/E7 ,8*B06 *< 05E,:;5 27,+E5 3B5 6* )%';'0#2':% %:M%H/:H'.K – UE&_ *i50 +5D.,254 ".a_ /0 675 *26,753+,. 47556 O+5<5+ 6* 675 05C6 hEB+5Q – ".a_ 4*85:854 +5D.,254 1/`_ /0 675 656+,753+,. 47556 •
?=FN 9*ON
".a_ /0 675 *26,753+,. 47556
-
?=FN 9*ON
".a_ 2*85 *B6 <+*8 2*..*/3> a ^;5 27,+E5 ,6 5C27,0E5 4/65
?=FN
-
9*ON
2:1-type silicate clay (expanding: Vermiculite group )
j5+9 7/E7 05E,:;5 27,+E5> 3B5 6* <+5bB506 4BH4:6B:*0 *< 1/`_ /*04 =/67 ".a_ /0 675 656+,753+,. 475564 O)%';'0#2':% %:M%H/:H'.Q@ • LfL /4 7/E75+ /0 ;5+8/2B../654 67,0 /0 ,09 *675+ 2.,9@ • 1=5../0E *22B+4> HB6 .544 67,0 /0 4852:654 3B5 6* 46+*0E.9 ,34*+H53 Y&T 8*.52B.54> ".J793+*C9. /*04 ,03 2,:*04> =7/27 ,26 8*+5 ,4 H+/3E54 67,0 =53E54@ •
9*ON -)6N
1/`_ /0 675 656+,753+,. 47556
--
9*ON -)6N
1/`_ 2*85 *B6 <+*8 2*..*/3> ` ^;5 27,+E5 ,6 5C27,0E5 4/65
9*ON
-
-)6N
2:1-type silicate clay (non-expanding) FB4
-/0:+/:0$
?)+1 > K**)/$
L2*'0)/
%$G56+,753+,. T26,753+,. G56+,753+,.
G56+,753+,. T26,753+,. G56+,753+,.
G56+,753+,. T26,753+,. G56+,753+,.
K+
Y93+*C/35 G56+,753+,. T26,753+,. G56+,753+,.
-':0+$ '( +210=$
1BH4:6B:*0 *< 1/`_ =/67 ".a_ /0 656+,753+,. 475564
1BH4:6B:*0 *< 1/`_ =/67 ".a_ /0 656+,753+,. 475564
L1H'. ). '+/12$,01* %2$$/%
".
P5 ,03 UE
K./$0*1"$0 %2$$/
G75 4/-5 *< R_ 2,0 h6 /0 H56=550 .,95+4
UEJ*26,753+,. 793+*C/35 475564 /4 4,03=/2753 /0 H56=550 ,3],2506 &K' .,95+4@
16+*0E
16+*0E =/67 YKT H/03/0E
!2$ 1,P1+$./ %2$$/ M).,).=
2:1-type silicate clay (non-expanding: Mica group) f,27 .,95+ 2*06,/04 ' *26,753+,. 47556 4,03=/2753 H56=550 & 656+,753+,. 475564
+ 5 9 , . + 5 6 0 S
R_ /*04 ,+5 :E76.9 75.3 H56=550 .,95+4> 67,6 D+5;506 675 8*;58506 *< =,65+ ,03 2,:*04 /06* 675 4D,25 H56=550 .,95+4@
Nonsilicate colloids (Iron and Aluminium Oxides) • Octahedral sheets: Fe 2+ or Al3+ in the cation positions. • No tetrahedral sheets and no Si. • Lack of isomorphous substitution (little –ve charge) • Small charge (+ or -) due to removal or addition of H + from surface hydroxyl groups. • Non-expansive and relatively little stickness, plasticity and cation absorption. • E.g: gibbsite, goethite, ferrihydrite and hematite.
Structure of gibbsite, an aluminum oxide. Consists of dioctahedral sheets (two octahedral) that are H-H bonded.
Humus (organic matter) • •
• •
•
)*0J2+96,../05 *+E,0/2 4BH46,025@ L*04/464 *< ;5+9 .,+E5 *+E,0/2 8*.52B.54 =/67 E505+,. 2758/2,. 2*8D*4/:*0K `eJkel L> aeJ%el T> aJdl Y ,03 'J%l )@ "26B,. 46+B26B+5 *< 7B8B4 2*..*/34 /4 ;5+9 3/m2B.6@ J;5 *+ _;5 27,+E54 O.,+E5 ^;5 4/654Q /4 35;5.*D ,4 Y_ /*0 ,+5 5/675+ .*46 *+ E,/053 <+*8K – L,+H*C9. E+*BD LTTY – W750*./2 793+*C9. E+*BD – ".2*7*./2 793+*C9. E+*BD YB8B4 2,0 ,34*+H .,+E5 ,8*B064 *< =,65+ 3B5 6* /64 E+5,6 4B+<,25 ,+5, ,03 " D*44/H.5 46+B26B+5 *< 7B8/2 ,2/3> D+/8,+9
Cation exchange capacity (CEC) •
• • •
•
LfL /4 675 /065+27,0E5 H56=550 , 2,:*0 /0 4*.B:*0 ,03 ,0*675+ 2,:*0 *0 675 4B+<,25 *< ,09 05E,:;5.9 27,+E53 8,65+/,. 4B27 ,4 2.,9 *+ *+E,0/2 8,F5+@ S6 85,4B+5 675 ,H/./69 *< 675 4*/. 6* 7*.3 *06* 0B6+/5064 ,03 D+5;506 6758 <+*8 .5,27/0E H59*03 675 +**64@ G75 8*+5 2,:*0 5C27,0E5 2,D,2/69 , 4*/. 7,4> 675 8*+5 ./N5.9 675 4*/. =/.. 7,;5 , 7/E75+ <5+:./69 .5;5.@ G75 2,:*0 5C27,0E5 2,D,2/69 *< , 4*/. /4 4/8D.9 , 85,4B+5 *< 675 bB,0:69 *< 4/654 *0 4*/. 4B+<,254 67,6 2,0 +56,/0 D*4/:;5.9 27,+E53 /*04 H9 5.526+*46,:2 <*+254@ L,:*04 +56,/053 5.526+*46,:2,..9 ,+5 5,4/.9 5C27,0E5,H.5 =/67 *675+ 2,:*04 /0 675 4*/. 4*.B:*0 ,03 ,+5 67B4 +5,3/.9 ,;,/.,H.5 <*+ D.,06 BD6,N5@
Quantifying CEC and AEC 1*/. LfL +5D+545064 675 6*6,. bB,0:69 *< OJQ 4B+<,25 27,+E5 *0 675 8/05+,.4 ,03 TU ,;,/.,H.5 6* ,F+,26 2,:*04 /0 4*.B:*0@ • LfL /4 5CD+54453 ,4 8/./5bB/;,.5064 *< OJQ 27,+E5 D5+ 'ee E *< *;50 3+/53 4*/. O85b['ee EQ *+ 28*. 2[NE@ • ' 8*.5 n k C 'e &a ,6*84> 8*.52B.54> /*04 *+ 2*8D*B034 • fbB/;,.506 =5/E76 [O5b@Q =6 K 8,44 OE+,84Q *< , 4BH46,025 O2,:*0> ,0/*0 *+ 2*8D*B03Q 67,6 =/.. +5,26 =/67 ' E *< Y_ *+ ' 8*.5 Ok C 'e &aQ *< 27,+E54 OE[5bQ@ •
"6*8/2 =5/E76 n E[ k C 'e &a /*04 *+ 8*.52B.54 fbB/;,.506 =5/E76 n E[ k C 'e&a OJQ *+ O_Q 27,+E54 n E[8*.5 27,+E5 n E[5b
' 8*.5 R_ /*04
n k C 'e&a R_ /*04 n k C 'e&a *+ ' 8*.5 O_Q 27,+E54 ,6*8/2 =5/E76 *< R_ n ao E[8*.5 R _ /*04 5bB/;,.506O5bQ =5/E76 *< R_ n ao E[8*.5 O_Q 27,+E54 *+ ao E[5b ' 8*.5 L,&_ /*04
,6*8/2 =5/E76 *< L,&_ 5b@ =5/E76 *< L,&_
n k C 'e&a L,&_ /*04 n& C Ok C 'e &aQ O_Q 27,+E54 n & 8*.5 O_Q 27,+E54 n `e E[8*.5 L, &_/*04 n `e E[& 8*.5 O_Q 27,+E54 n &e E[' 8*.5 O_Q 27,+E5 n &e E[5b g7,6 /4 5b@ =6 *< ".a_ O&d E[8*.5Qp
G75 4*/. LfL /4 46+*0E.9 ,I52653 H9 675 0,6B+5 ,03 ,8*B06 *< 2.,9 8/05+,.4 ,03 TU D+54506 /0 4*/.K • &K' 8/05+,.4 q'K' 8/05+,.4 • Y/E7 4,03 ,03 TU 4*/.4 q 4,039 ,03 .*= TU 4*/.4 • r q /03/2,65 2*06506 8*+5 LfL
•
•
G9D/2,. LfL ;,.B54 <*+ 3/I5+506 4*/. 65C6B+54K -')* /$D/:0$
?$R>4SS =
1,034 O./E76 2*.*+53Q 1,034 O3,+N 2*.*+53Q s*,84 1/.6 .*,84 L.,9 ,03 2.,9 .*,84 T+E,0/2 4*/.4
aJ% 'eJ&e 'eJ'% '%J&% &eJ%e %eJ'ee
•
W+/02/D,.[D+53*8/0,06 2,:*04 * Y_> L,_&> UE_& ,03 R_ – )5B6+,. *+ H,4/2 4*/.4K L, _&> UE_&> R_ ,03 ),_
•
G75 46+50E67 *< 2,:*0 ,34*+D:*0 O.9*6+*D/2 45+/54Q /4 35D5034 *0K – L,:*0 27,+E5 O" 27,+E5> " ,34*+D:*0 46+50E67Q – S< 4/8/.,+ 27,+E5> 3565+8/053 H9 675 4/-5 *+ +,3// *< 793+,653 2,:*04 O# 4/-5[+,3//> " ,34*+D:*0 46+50E67Q
"._a q rY_ q L,_& q UE_& q R_ n )Y`_ q ),_ rY_ /4 B0/bB5 H52,B45 *< /64 ;5+9 48,.. 4/-5 ,03 7/E7 27,+E5 3504/69> 67B4> /64 ,34*+D:*0 46+50E67 H56=550 "._a ,03 L,_&@
Determination of CEC " 2*0;50:*0,. 8567*3 6* 3565+8/05 LfL ;,.B5K )Y`T"2 O,88*0/B8 ,256,65Q 8567*3 HBI5+53 ,6 DY d@e H9 .5,27/0E 8567*3@ • g750 4*/. 4,8D.5 /4 5C6+,2653 =/67 ' ) )Y`T"2> 675 5C27,0E5,H.5 2,:*04 ,+5 +5D.,253 H9 )Y`_ ,03 LfL H52*85 4,6B+,653 =/67 )Y`_@ • G750> 3/I5+506 4,.6 O5EM R&1T`Q /4 055353 6* +5D.,25 )Y `_@ G75 .5,27,65 2*06,/0/0E 675 )Y`_ /4 , 85,4B+5 *< 675 LfL@ •
') )Y`T"2
A,45 2,:*0 ,6 675 5C27,0E5,H.5 4/654 s5,27,65 2*06,/0/0E H,45 4,6B+,:*0
Determination of CEC
Saturated the soil with NH +
Measure exchangeable
Leach NH4+ with K+
Measure CEC (NH4+)
Base saturation (BS) •
A,45 4,6B+,:*0 OlA1QK 675 D5+2506,E5 *< 6*6,. LfL *22BD/53 H9 L,&_> UE&_> R_ ,03 ),_@
•
A,45 4,6B+,:*0K O6*6,. H,454[LfLQ C 'ee
• " lA1> " 675 ,;,/.,H/./69 *< L,&_> UE&_ ,03 R_ 6* D.,06@ • " 4*/. DY> " lA1>
Anion exchange (AEC) • • • • • •
"0/*0 5C27,0E5K ,0/*04 /0 4*/. 4*.B:*04 67,6 ,34*+H53 6* O_Q 27,+E5 4/654 *0 2.,9 8/05+,. 4B+<,254 ,03 TU@ G75 O_Q 27,+E54 ,+5 *0 675 8/05+,. 53E54 ,03 TU@ "0/*0 5C27,0E5 ,.4* *22B+ =/67 TY E+*BD *0 675 793+*C9. 4B+<,25 *< N,*./0/65@ Z/4D.,258506 *< TY /*04 *0 793+*B4 P5 ,03 ". *C/354 D,+:2B.,+.9 /0 7/E7.9 =5,675+53 4*/.4 *< 675 6+*D/24 ,03 4BH6+*D/24@ "fL "> ,4 4*/. DY #@ "fL /0 ,2/3 4*/.4 7/E7 /0 'K' 2.,9 q &K' 2.,9
Y&WT`J q 1T`&J q )TaJ q L.J
Acid and base concept • •
"2/3K " 8*.52B.5 67,6 3*0,654 Y_ 6* 4*85 *675+ 8*.52B.5 /0 =,65+@ A,45K " 8*.52B.5 67,6 ,225D64 Y_ /0 =,65+@ H2O ! H+ + OH-
(weak acid, donate H +)
"F,2754 6* ,0*675+ Y&T 8*.52B.5
H2O + H+ ! H3O+ (weak base, accept H +)
16+*0E ,2/3K 'eel *< 3/44*2/,:*0 *< ,2/3 =750 ,3353 6* =,65+@ • g5,N ,2/3K 'l *+ 4./E76 3/44*2/,:*0 *< ,2/3 =750 ,3353 6* =,65+@ •
HCl ! H+ + Cl- (Strong acid, 100% dissociation) CH3COOH ! CH3COO- (Weak acid, 1% dissociation)
Soil pH
1*/. DYK 3565+8/0,:*0 *< /*0 793+*E50 OY_Q 2*02506+,:*0[,2:;/69 /0 4*/. 494658 • S6 /4 05E,:;5 .*E,+/678 *< 675 ,2:;5 Y_ /0 4*.B:*0@ •
#A n J .*E tY_u
n .*E '[tY_u •
TANNU '( #:0$ TA U '( #:0$ Q1/$0 V Q1/$0 V SXSSSSSS4 4 D 4S
DY *< DB+5 =,65+K DY
n J.*E tY_u n J .*E t' C 'eJdu n J OJdQ .*E t' C 'eu n d .*E 'e ndC' nd
v
n .*E t'[tY_u n .*E t'[t' C 'eJdu n .*E 'ed n d .*E 'e ndC' nd
Soil pH •
G75 DY 42,.54 +,0E54 <+*8 e 6* '` =/67 d ,4 675 05B6+,. D*/06K TANU D T7A
•
"6 DY d> 675 Y_ 2*02506+,:*0 /4 5bB,. 6* TYJ K TANU V T7A
•
G75 Y_ 2*02506+,:*0 7,4 , 650<*.3 27,0E5 H56=550 5,27 =7*.5 DY 0B8H5+> 67B4 , 4*/. *< DY % 7,4 'ee :854 8*+5 Y_ /0 4*.B:*0 67,0 , 4*/. =/67 , DY *< d@
Classification of soil acidity
The sources of Hydrogen ion/acidic in the tropic soil
V"68*4D75+5[D+52/D/6,:*0 Xs5,27/0E wTC/3,:*0 *< D9+/65 xTC/3,:*0 *< 2*885+2/,. <5+:./-5+4 yTC/3,:*0 /0 2758/2,.4 O1B.D7B+Q zcD6,N5 *< 0B6+/5064 H9 D.,064 {fC27,0E5 *< 0B6+/5064 3B+/0E 0B6+/5064 BD6,N5 OY _ /*04Q |Z52*8D*4/:*0 *< TU }Z52*8D*4/:*0 *< TU ,03 +**6 +54D/+,:*0 OLT &Q
Influence of pH on nutrient availability and microbial activity •
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S0 4./E76.9 6* 8*35+,65.9 ,.N,./05K $ " 8,2+*0B6+/5064 O5C25D6 WQ ,03 U*@ $ # 8/2+*0B6+/5064 OP5> U0> ~0> LB ,03 L*Q •
•
A,265+/, ,03 ,2:0*8925654
1*/. DY
Buffering capacity (BC)
ABI5+/0E 2,D,2/69K /4 675 ,H/./69 *+ 2,D,2/69 *< 4*/. 6* +54BDD.9 ,0 /*0 6* 675 4*/. 4*.B:*0@ • S6 85,4B+5 675 2,D,2/69 *< 4*/. 6* 8,/06,/0 675 2*02506+,:*0 *< 0B6+/5064 /0 4*/.@ • P*+ 5C,8D.5K g750 D.,06 +**6 ,H4*+H4 0B6+/5064 4B27 ,4 R_ <+*8 675 4*/. 4*.B:*0> 675 R_ /0 675 4*/. 4*.B:*0 =/.. 352+5,453@ G75 8/05+,. 4*/.4 +54BDD.9 675 R_ 6* 675 4*/. 4*.B:*0 <+*8 675 5C27,0E5,H.5 6* 8,/06,/0 675 R_ 2*02506+,:*0 /0 4*/. 4*.B:*0@ •
• " LfL> TU> ,03 *675+ 4*./3 2*04:6B5064> " AL@
"4 LfL /02+5,454 =/67 /02+5,4/0E 2.,9 2*06506> 675+5<*+5> AL /0 h05J 65C6B+53 4*/. q AL /0 2*,+453J65C6B+5 4*/.@ • AL /4 ;5+9 /8D*+6,06 4*/. D+*D5+:54 67,6 46+*0E.9 /0•B50254 0B6+/506 ,;,/.,H/./69@ •
Buffering capacity (BC) •
S8D*+6,06 *< HBI5+/0E 2,D,2/69K V G* 504B+5 +5,4*0,H.5 46,H/./69 /0 675 4*/. DY ! W+5;506 3+,4:2 27,0E54 *< 4*/. DY =7/27 7,;5 4/E0/h2,06 5I526 6* 7/E75+ D.,064 ,03 4*/. *+E,0/484 ! fC,8D.5K ,2/3 +,/0 X S0•B50254 675 ,8*B064 *< ,850385064 O./85 *+ 4B.D7B+ +5bB/+53 6* 5I526 675 354/+53 27,0E5 /0 4*/. DYQ
•
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Determination of soil pH: Dye method
Determination of soil pH: Electrometric method
Methods of increasing or decreasing soil acidity •
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•
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Lime requirement •
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•
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Lime requirement
//@ L758/2,. • S02+5,45 4*/. DY • +53B25 ". ,03 U0 6*C/2/69 • S02+5,45 675 0B6+/5064 ,;,/.,H/./69 ///@ A/*.*E/2,. U*46 4*/. *+E,0/484 ,+5 • 8*+5 ,2:;5 =/67 /02+5,45 4*/. DY
Lime requirement
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U*46.9 <+*8 ,/+ ,03 =,65+
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Movement of ions from soils to roots
4 F
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Root interception •
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•
S*04 *0 675 +**6 4B+<,25 O5@E@ Y_Q ! S*04 *0 2.,94 ,03 TU 4B+<,25@
•
/*04 ,34*+H53 *+ 675 4B+<,25 *< +**6 25..4 ,03 2.,9 D,+:2.54 ,+5 0*6 75.3 :E76.9 HB6 '%+)**1/$ =/67/0 48,.. ;*.B85 *< 4D,25@
•
S< 675 +**64 ,03 2.,9 D,+:2.54 ,+5 /0 2.*45 2*06,26 =/67 5,27 *675+> 675 *42/..,:*0 ;*.B85 *< /*04 ,34*+H53 *0 +**6 4B+<,25 8,9 *;5+ H9 675 *42/..,:*0 ;*.B85 *< /*04 ,34*+H53 *0 2.,9 D,+:2.54> ,03 675 /*04 ,34*+H53 *0 2.,9 D,+:2.5 8,9 H5 5C27,0E53 =/67 675 /*04 ,34*+H53 *0 +**6 4B+<,25 3/+526.9 =/67*B6 h+46 H5/0E 3/44*.;53 /0 4*/. 4*.B:*0@
Root interception T42/..,:*0 ;*.B85
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AN
EN
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G75 /*04 75.3 H9 5.526+*46,:2 <*+254 ,6 67545 4/654 *42/..,65 =/67/0 , 25+6,/0 ;*.B85@
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EN
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g750 675 *42/..,:*0 ;*.B854 *< 6=* /*04 OY_ ,03 R_Q *;5+.,D> /*0 5C27,0E5 *22B+@
Root interception • Root interception can be enhanced by mycorrhiza which colonization is favor under conditions of slightly acidic soil pH, low P, adequate N and low temperature.
g/67*B6 2%-$..!'3"
g/67 2%-$..!'3"
Mass flow U,44 •*=K U*;/0E *< 3/44*.;53 0B6+/5064 /0 •*=/0E 4*/. 4*.B:*0 6*=,+34 675 +**64 • S6 *22B+4 =750 /*04 /0 4*/. 4*.B:*0 ,+5 6+,04D*+653 6* 675 +**6 ,4 , +54B.6 *
C N a O 2 3 + N - C O a2 3 -
+
