preoede4 by one ar more steps above it (� 17).

It it

ia as�d

the.t 1bo CO.iSta.nt mwl ia e<;pal _{b) the ra.te} ol� e�tion of the leas ooluble form of potasBiua, then the _more

solttlle

portion will be

npl'eeentea. by

the sa or potaaemm extzooote4 _in e::mees ot this value. For o0\'l'Ven1f:f'l...oe1 the potua:Wm extracW at a a:matant

rate

io oallei. "ocr....stnnt rate" potMshml arJl the potassha extlraoted in emeas

of 1hia rata :S.n _{the tirst extracts}

1a eallecl the

" step" potasa!um.

A OOI!i>� of' the ext:ractim data at _{the 11011 to aoht} n.t:los o� lt

_1�,

_lt lOO _ana ls 9001 sl't..o� that 'the " .tep" potasldua _{1e r�::d.y the}

same tor each r _{a.ts.o, an4} -that the "omstant rate" pote.Mium Sncreuea with the

'ritiening

1� t1.oa.

In the l.eMlting elq,)el"imenta, a near� oonatant Z'&te

ot

u:tl:ftloticm wu reoOI'\'h!lct after 30 _- 60 mSnutee leadlilC ( 11'1gure l.d) . U th1a mte oorrelllpOI'Ada to ihe "oon.tsnt _l'&te" pctuamm _unSer lt!Jadh1ng, _{thm eottn.•} polaticm back to m.-o "VVl.liM

ot

th1a

OCilftant

rate t:l eZtn:.tion llhcW4

giw

the 8Q!.li'ftlct ot i.be "step" potuau ot batoh extuwticma. Inspeot:l.z

of' the 'ft)laM Gm"'ftta dlOII'a tbt.t the leeah1.n8 "nep" potua:'ta

ia near� S4entioa1 with the batGh

"nep" pow..S..

!he 4eptna.rae t.Jt the pet11uaSDDl leaoho4 OD the

<volUM fll

leaabate

at

al.tJIIt' 1D mec'"n l.MoMng atea, IIMn

that

_{\be "at.p" peta.taa} ia :not ot unl.mite4 aollibUi\V.

With batell

«<t.ftotima, 1bia ia .tunm alao. At _{the � IICd1 to acSA n.tioa,} 110ft

_..,tiona

are DIO...ry 10

the

"II'Mp11 pota.-dta,

e.g. tit

a

mil to

ao:14

atso ot

lt lilrt

up to • �ticna aq

be

neoe� to tr:ldalict aU 1he "

atep

" petaaha, whereaa

5 . 0 . �

4

0 � . <I> s � ..-1 3 . 0 'fj <I> +> 0 «l '-· �.)

2 . 0

I< <I>

§

..-1 (Q 1/J _{1 . 0} «l � 0 p. o . o MlDDLERURST S i lt l oam .

....

.... ,. I I

1 2 3 4 5

09 FIGURE _{1 7 .} OMAKERE c lay loam .

/ /

1 2 3

4 5 NEW PLYMOUTH sandy lo am . 1'- I I

1 2 3 4

5 Extract Number Extre.ct Numb er Extract Numb er

F ig . l7 . - P o t as s ium so lubl e in

B

rat i o of s o i l

�

o acid

1 : 100 ,

Exche nP, eab l e p ot a s s ium removed

!i / 10 RN03

pr�or �o

first d iP.;e st i o n .

A - B • • • . . • . • • • " C on s t ant Rat e11 Potas s ium.

Hat ched ar ea • • • " St ep" P o t as s ium.

at

a. ratio

of lt 100,

the " step" potassium 18 l'eiiDVcd almost entire� in

2 extractions.

Whereas the "constant m.te" potassium is •en to be a. 1Unoticn

of

the mU to eo14 mt!o or ti�.e leaching rate _{an4 ia} ohareoterist1o ot each

MU

only man

tl'V!

ratio of BO U

to

aoi4

is ver:1 'fd.c!e

(11100

or 8f'ea.ter) ,

the

"step" potas&Sula

is _a aetinite

t.r:oaotim, independent

of the time _of

hea.ti.ng1

noid oon:)entl'a.tion, ratio of lllU to acid

ana. rL the method ot

extraction.

Rouse and Be.rtrllmscm

( 1949) and

Pratt

( 19152)

_{llh� that}

potassiua 1IU ext.�Mted tran all texture tl"aotima on <U.geaticln. _with

li mfOs,

with the aDount � potaMSnm e�

moreaaing with

1n<ll"eaain8 tinerlesa ot

tlexture.

Al�

ftriaticna in the 11ezture _{or the}

son., pl"e"nlllile4

_81\V

- ·-·---. .... ... --- - · - - - - ---

uaat aeneral. toW potuaiua

e:.lttra411ed

ha� the 'tlhal.e mila tlo h 41tte:rent tdtlll"e t.r-Mtima,

about

one hall' ot _{b potusila}

extlncte4 ,.. a.ttrlbute4 to 1be _{alq �crw. ln 1be pl'888lltl �,} est:r:n.sticlll ot the _texture

t.moti�,

_{OOIII'fle sanl;}

tine llaD!, .U-t: ana olq;

llepU"a.te4 � b

eo�e

uae4 tor

the long

_term

�Sng

experiment, a.t A

range

of solid to eoi4

ra.tioa, oont1rme4 1N.t potUid.Dal wu est:ft.oted traa _, all b:Mticna with _-1he

grcllteet

•run1111 pel' unit 1lldaht bein8 e�W

.,/'

-·---· --- -·- -... ---··---"" ----·--- --- .. -

70

1be ooarae onndo gave "1aonatrutt rate" potft..qsium

values

olo•

to t�.oao f�mnd f?r �tc oor.�)s;v1nd.i.ng f:L•e G��s. 7\.�:o;:le:pt.

ICJ.'t' the l!!altla tran

the Middlt!lhurst

ailt

1�.m, �1lc " a t.;t"1fi" potaasium frr 'the ooo.rae sru1i1a was nuch leM than that for the fine _{M.."lds. Tt'!:>} coarae M.nclf.i �1owed no " step•

pot!'�n 1v.m.

The ooarse Mod f'mm the l.H.ddlcllurst ailt loam Ot1

:i.!'.apeotion

!k"ltim· mJ.orosoope, wa..-; see.n to be

lnrgely �flitet

of' tiJ]e sar.d sia

crystaln jo::lned by a. t.J.a trtx of indetini te CGNJ98ition_ }l_tl t.

apparently

of ·- ---· ·--- ---·· - .

aeaquiox:i&OJ, o lo!Jaly rssed>l:L'1g limon:tte. On d:lgestion with

l! HNOs,

this mnt:r'i."'C d.iaac;l;;ed

pro{blo:l.rlJ

a

s::>lution

..retj high in iron am leati.P..g a

resi&ua, predom:lJ"I..ately

fine

8tll'l4. The large

anamt r:£ pota.r.�aitn 1Ulemte4 ln the N.r�t a...'1d seco1ld rtXtrQQ.t:ica'lS ia tr �sumed to have «me tm:n tbia

JUal"'etr.totnr.e b!"!a�, ':'lhioh by _obacrtraticn was oomplete after 2 extracticns. 'rhe other ooarse IJal'Xla extn.oted, i. e. TliUpo, �. Idaburn and

Uima.tangi,

were

p:redornlnatcly

of

��--S!��L.J'.truoture

of oomposi tilm fd.:nUar to tle tir4 aon4, but w1 th 'the ldnburn course aana., no

mtioftable AIIOJl'lte ot l':'l!orut W'I'Cre ;:crose:rlt.

The mttraot:ion IX' t ter:na o£ the f'�ne sn..7lde

(Teblo 00) ,

showe4

only

a

RUper!'icinl

�aemblcnce to

those of the l't1ola oo:Us. The "con•ta..nt rate" potassium 1llU.\ less ··lhm that for U1e t<!Jo.le oons at oor.!pro:'3ble ratioa and tna " step'' potaosium1 who:r.t'l present, VJ:l$ lees than that for 'the vi'lal.e

eoila, em�rt

fbr �e H:imntnngi oom·ne

s.-·lr..d., 'Obiah

:J s

mainly

_BM4

(

_oa.

00%) .

Where the fine eonc1s �re

e::rt.T30ted

at mare thon one

mnd

to acid ratio,

it 1'lM not:lce&lle that

:i.ncn:'€o.aing

the ratio .,:r seid 'tio MliO , pl't)duoe4

Uttle oh� 1n the �nou:n:h of pow�da:n _{�xtfiloted at tntios Wider ihm}

l a l.Si

_{for fue �aJ.po and Toko:ral'!l fine san.cla, and}

ls

25 tor the Otna1aa'e fine sand, _{hut tbat digeatian .1.t tile ratio} lc lOO "l:t!n-acte<l ��

"OCR.'lstant

:rote''

potaseitrn

:f'rom the lliOOle."»Jrst ond Idalml'n tine Sl1r".4s than dicl digest:i'Xl at a :m:tio cf 1� 00.

L"l:Jpeotio..'1

o� Table 21, wh:i..0:1 eta out 1he extraction data. ftJr' 't!:lP, sUt f.rMtions. �haws t.hat _{all the rd.lta extracted, h&4 appreoisble}

--

-- --· --- - ---. ·-·-·--- ---·

" ste-p" potassium,

_{with b emq,til'%19 of the}

'l!okanezu d '.1'� silta m:1eh

hru1

" step" po tasaill!l values of o.o me

� and

o. :a ue

� rot�J.PE)ct1:'Mly.

rhe

"Q)M'tant

rt�:te'' potassitm was ore un! a lm.lf tl> three t-'..mes tha.t d 1:he Cf.Jrr'esponi1n[!

tine

aaroa; mr.nept

fcrt:' the W�l"a

a.ilt

loMtt

W�8

both

itte

ailt

and fine IWlc1 had

appro:dmately

the aamD "oonat.ent _rate�'�

potuaiua.

With the tiw IJI')tls where it1e silts -were extl"edte4 at ll'iOI"e than one aUt

to ao1d

atio, inGl'eaaq

tile IDCJ.Ult of ao14 J.nort�J$S84 tJw "oonatnnt rate• potassillll. With tl'le two s:i.ltt� •hich

lil)Oft.W. large

em.r.untll

ot

pOtda�ma to tbs

f:irst ! llNOs

extrnctic1la, via. the Hiddlelm.rst _{ana ldabUI'D ailta, tbe}

" atep" potaaaitn 1a

�-

m1 �p:rro:�:1roo:tkln at 'the nar:rot:'er rntioe u

71

IN

Tima or

Iif'..ntil18

15

rn�..nutes.

Coarse sand Ratio

''Step"

trl:a

Taupo 8M4

1 : 1 �

o.a1 o. 09 o

.

o

Mida:J.eh<nost 1: 1� 0. 73 o. m. 0. 19 0. 18 1.9 aUt loam

Qnekere 1: 1� 0. 20 o.oo o. ao 0. 19 o. IB o.o

olt:Ig loam

ldabt.Un

1:1�

o. �> o. u

0.14

_o.l.S o.l6 o. 1 t'ine

aand,y

lom

ltima.tangi

1: 100

0.65 o. 4o 0.40 0. 41 0. 2

coarw.:

sand.

Tiloo or nea.ti� 15 Illinutes.

Pine ama Ratio Extmot lit.trrber

"Step"

rran 1

lifew

P�1th

1: 12-� 0.15 o.l3 0. 12 o. o

eane\v loan

Taupo 1 : 1� o.u o.oo

o.os

o. oo

o. 1

sand

1: 100

o. IB

o.1a o. 1o o. 1o

o.1

M1ddlehlrst

1 : 5

o.oo

0.90

o. n

0.41

0. 26

- L'iil t lol!l!l 1: 1� 1.49 o.aa

0.47

0.41

0.32

-

1 z 25

2. 00

1.20

0. 75

o.oo o.oo a. a 1: 50 2.45 1. 27 1. 05

0. 72

0.

7₆

2.3

1: 100

3. 01

o. oo

0. 97

0.95

0. 95

2. 2

Tokanaru 1 : 5 o.u . o.u

0.09

o. o

fine

san�

loa!\ 1: 1 � 0. 22

0.17

o.l9 O. lB

0.

17

o.o

1z 25 o. aa o.l9

0. 21.

0.18

0. 20

o.o

1: 50 0.24

0. 18

o.la

o_.l9

0.1$)

o.o

1 : 100 0. 25 o.19 o.la o. l8 o. 1

<:makere 1 : 5

0.40

o. l8 o.l3

0.13

o. s

c1ey _loam

1t 1�

0.48 o.:K o. M _o.M.

0. 20

_o.z

1i 25 o. oo 0. 33 o. :so o.s1 o . 3o o. :s

lt 50 o.oo

o.35

0.:50

o.so

o.30

0.3

la 100

o.eo

0.45 0

. 39

0.36

o.:s

Idabum

1t5

0.72

0.45

o.as

0.15

o. u 1.0 fine

OMI.'\y

loam

11 1�

o.B4

o.M o.<M o. aB

o.ae

l.O

1 1 25

l.C8 o.s2

o. :IB

o

• ...a

o.85

1. 0

1s 50

_1.26 o.81

o.so

o.48

0

.48

1.1

1: 100

1.49

o.oo o.Gs _0.62 o.a

'rima:ru 1.100

0.45

o. �

o.Sl

o. aa

0.2

81lt

lo•

llalOQd)e 1a 100 o.Go 0.41 o.:sl 0. 27 o ... silt loam

l&at ... ltlOO o. l9

o. 19

o.u 0. 15 o. o

silt

1o•

Waipara

la lOO

1.

12 o.M o.s2

o.so

_{0. 5}

aUt _loam

In document A fractionation of acid soluble non exchangeable potassium in some New Zealand soils into available and non available forms : a thesis presented for the degree of Doctor of Philosophy, University of New Zealand [Massey Agricultural College] (Page 76-79)