Phosphate fertilizers for Hawaiian soils, and their availability

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Material Information

Title:
Phosphate fertilizers for Hawaiian soils, and their availability
Series Title:
Bulletin / Hawaii Agricultural Experiment Station ;
Physical Description:
45 p., 4 p. of plates : ill. ; 23 cm.
Language:
English
Creator:
McGeorge, W. T ( William Thomas ), 1886-
Publisher:
G.P.O.
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Soils -- Hawaii   ( lcsh )
Phosphatic fertilizers -- Hawaii   ( lcsh )
Soils -- Phosphorus content -- Hawaii   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Statement of Responsibility:
by Wm. T. McGeorge.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029613063
oclc - 10082368
Classification:
lcc - S399 .E2 no.41
System ID:
AA00014544:00001


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A WAllJ. AIJLUUUJ L JL. U CAL .Ci.JlJLlJ.-J. DL A-.LJLU DaT iUJWI :.i:

[Under the supervision of A. C. TRUE, Director of the States Relations Service, TUnited.t: .i
Department of Agriculture.]
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E. W. ALLEN, Chief of Ofice of Experiment Stations.

WATrrR H. EvANs, Chief of Division of Insular Stations, Ofice of Experiment

STATION STAFF.

J. M. WESTGATE, Agronomist in Charge. ,i
J. EDGAR HIGGINS, Horticulturist.
M. O. JoHNSON,1 Chemist. .
F. G. KRAuss, Superintendent of Extension Work.
J. B. THOMPSON, Assistant Agronomist, in Charge of Glenwood Substation.
ALICE R. THOMPSON, Assistant Chemist.
V. S. HOLT, Assistant Horticulturist.
C. A. SAHR, Assistant Agronomist.
A. T. LONGLEY, In Charge of Cooperative Marketing Investigations. .i
J W. LOVE, Executive Clerk.

1 Appointed July 25,1915, to succeed Wm. T. McGeorge, transferred to U. S. Department of AJceui0l
ture, Bureau of Chemistry, July 8, 1915.
(2)






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I Recommended for publication.

.. A. C. TBir Director.


Publication authorized.
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.1 oJLUUUBIUrNo,

Secretary of Agricuture.

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A~~pw~a llpnent----lr----------l----r-l-- ----------.. 4

S .d.................................................. 41


lTe determination of phoephorie acid in Hawaiian soils.- ..-..- -- 42












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J... .AL. .. J..- vuJl.paliULlb n L Ve JiU.Je.Uc Uin LJPayuazwsUU OlJ J .iAJ.Jp i ..L1 .A W.. -a.-r...:'..
let I. Fig. 2.-Comparative influence of phosphates, Expi
II, Millet I................................ ...... ...
IT. Fig. 1.-Comparative influence of phosphates, ExperimeHt I.ii. ..
let I. Fig. 2.-Influence of cowpeas on the availabili ty f B IWdI0:
phate rock, Experiment II, Millet I.............. -
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;Hawaiian soils as well as the manner in which phosphates are locked
S....... ti e soil. x ese investigations included several series of pot
peients. One series involved five successive crops and extended
ym er a period of two and one-half years. In another three suc-
:ienive crops were raised. In connection with these experiments
determination were made of the total phosphoric acid in the' soil,
i. e percentage of phosphoric acid in the soil and in the various phos-
phatew soluble in different solvents, and the quantities of phos-
plwor acid absorbed by the crops grown. The principal crops used
in the experiments were millet, cowpeas, and buckwheat. Such
experiments wre considered necessary in order to be able to recom-
mend the most economical form of phosphate to use on the peculiar
Soils of Hawaii.
SanA. Rl Sta. Bb. 35(1914) C s4 (115).
N p*Moesa imee eaarrid calt thfe work were at undertaen In cooperation with the Bado Slag
r f 1Amlda of the Offei AgrleItural ChImuata, bat have been counted d broad-
ag W b fbrifib agin airegard to phosphate fertaizers for Hawafian saa.
.1 (7)
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Soil SoU A
No. 1. No. .1

Moiture.... 7. 65 12 1
Per cent,: Pefr
Moisture-................ ............................... ............. 7.65 12
Volatile matter.............................. ......... ........ .. 8.42 2
Insoluble matter...................... .............. ...........- ... 8.49 830.74
Ferric oxid (FeOa).............................. .... ........ ...... i.1 : u i
Alumina (AlOs) .......................................................... 12.85 17.52
Titanium.oxid (TiO) ......................................... ......... 200
Manganese oxid(MnaO e)................................................. .24 4 .
Lime (CaO).............................................................. ...
Magnesia (MgO) ......................... ..----- .....-- ...-- ............. 8.71 .
Potash (K O)............................................................9 .
Soda (NasO)............................................................. 1.:1 .S
Sulphur trioxid (SO ).................................... ...............8 .
Phosphoric acid (P )--....---..........................---................. ..-57

Soil No. 1 represents the type to be found in and about 1~ .:: :
It has a sandy texture and is derived in part from the disinteg,
of blaok volcanic ash. It is used for truck gardening,. Ari P,
bananas.
Soil No. 2 is the highly ferruginous type of red clay so abuna~.
the islands.
Soil No. 3 is a red soil very similar to No. 2, differing in that 4.ITC "
has a better texture, that is, less clay.
7 "7 7 4" "L "
METHODD, :i
The method used in preparing the pots was similar to that:I 1l
posed by the Basio Slag Committee of the Association of O Biil
Agricultural Chemists. Tin pots were used instead of clay poti ::;3:iii
order to eliminate the loss of fertilizer through efflorescence. ~ladi
pot contained 6 pounds of soil. The forms of phosphate used wtes 7
Double superphosphate (46.25 per cent P2,O), acid phosphate (19.WXNi
per cent PO,), four different Thomas phosphate slags (A, 18.38 J"
cent PO,; B, 19.04 per cent PO,; C, 13.31 per cent P2,O; D, 18
per cent P2,O), phosphate rock (29.4 per cent P,O), comm
sodium phosphate (20.87 per cent P2O0), trimagnesium ph
(54.1 per cent P2O,), tribasic potassium phosphate (33.4 per
PO,), dibasic potassium phosphate (40.8 per cent P2O0), mono
potassium phosphate (52.2 per cent PO,), reverted phosphate (1
per cent P2,O), bone meal (27.76 per cent PO,), ferrous phosp.
(37.8 per cent PO,), ferric phosphate (31.8 per cent P0, ), .al.i
phosphate (58 per cent PO,), and titanium phosphate (34.1 per..-








phosphates wero, grkad to about, the same degree o
Each pot received an application of nitrogen as aoiu
,and blood, potash as potassiuma sulphate, and lime as calcium
t.The lime wassadded, to counterbalance any, influx ces
the basic material M' the slag igt exert, and was added in
of the limo requmrment as deterie by the Veiteh method.
crops -used inoluvded Japanese Mmillet cowpeai, buckwheatt.
and turnips.
ertiliser applications are represented. in the table as follows:
Os6per cent nitrogen from i.blood and 0.01 percent from
nitrate.
OM0 per cent nitrogen. from -blood and 0.015 per cent from
nitrate,.
0.10 per cent potash (RO) from potassium sulphatelp
T r m0.15 pe et oth omotassium sulphate.
-0.10 per cent cal ium carbonate plus that required by the
ieitchmethod.
r0.15 per cent clium. carbonate plus that required by the

?-==O.007 per cent phosphoric acid (P205) from the phosphate
7,,AsP, 0014 002, nd 028per cent phosphoric acid,

L-legumea.
Jnone series: o! the experiments,: green manure in the form of
vAl-m~acerated cowpea vines was added at the rate of 2 ounces per
-`; in the othern re manure was added. 'All applications were
xaade, in. duplcate, two weeks before seeding. The pots were watered
vm











KA, E&XPERIMENT 1.
ln the, firot experim~oent, soilNo. 2 was used,. a heavy clay soil very
defiient in available, phosphoric acid. In Table II are given the
nubers IOf the pots, kind and amount of fertilizer added,: weight
of. crop 'both grew.. and dry, weight of heads, and plants per two
ta. The first, crop, Japan4ese millet, -was planted July 31 and
Wse October 20. The soil was then dried out, aerated, returned'
to the pots, and planted to cowpeas November 17. This crop was
ouet on Jinuary 17, weighed (each pot separately), and returned to
the respective pot&. Without any further addition of fertilizer the
pots were planted-to buckwheat- February 6, which croj> was har-
vested March 27. The soil was again dried out, well aerated, and
again planted to millet May 18, without further addition of fertilizer.
M Tis crop was harvested on August 10. Ile soil was agami dried,
waoadwRmxda bvad fe ulapiaino i
trgnadMsbu opopoi aiia gi latdt ilt











TABLE I.-Efect offetiliers on-weig


Milet 1. cowpeas. Bcwet iltM
Pot




Nos Fert~iier ade. Weight of crop. Weigh ofgh crpNeihufcrpmeghorp
ber of ofecrop, ber of eofbrf
Green. Dry. Heads. plants. green. plants.pat.d lns.GeL
Green. Dry. Gren Dry, Gree Dr..ui

1,2 ..... N-K C L ...................... 46 18.5 4.5 8 43.2 '8 2. 008 55 2. .88 72 40'
56 ..... N-K-Ca.............. 32 13.0 4.0 7 43. 8 4o .... 0. 50 498 ...
,10 .... N-K-Ca-L;."............. 27 12.5 3 .0 3 46.08 245 1.8 5.5 74 648., :
1314 ... N-K-C& .......................... 20 10.0 2.5 4 50. 8 80 1.8 12 2. 32
1718 ... N-K-Ca-L-P1 (sa A) .......... 35 12.0 2.0 5 70.48 340 1.8 7.5 33 6610 20
2122 ... N-K-Ca-Pj. sa A ............ 44 16.0 4.0 6 69.4 8 3. 159 7.: 3.1 681 72 1
2(s. g--O B) .......... 66 28.5 4.0 4 78.48 345 i.
29:30:. N-K-Ca-Pl. sa g B ............ 87 34.0 6.0 8 78.3 15 1.8 80 3., 6 9 2.
33,4... N-K-Ca-L rP ( )Q.......... 70 27.0 6.0 8 83.4 6 2. 148 7.5 3. :18 2.. 1.
18. N-A-aeC- ............. 74 29.0 .0 8 83.08 405 1.
41Y42... N- ) ....... 84 2.0 5.0 8 55.2
f46... N-K-C-P/Slag ....... 90 39.0 8.5 8 70.58
4910... N-K-Ca-L-P11 ai phospate). 119 45.0 0.0 8 43.5 65 1.8 &5 178 $1a 1. .5
53:54... N-K--Car-P12(ala phospae).... 125 50.0 12.0 8 M5.'28 4. 698 6. f .
57,58... N-K-Ca- -P/2(hs at rock). 12 6.0 1.0 3 61.08 427 1.8 7.. 3&: 1.a10 T6
61, 62.. N-K- sP112.( osphate rock)..., 28 11.5 2.58 8 69.2 8295 1. 8 D!9 &
65,6e... N-K-ar-L-Pili (sodium phos- 102 37.0 8.0 7 75.08 425 1.8 760 3A O6 10 -'5 *2 Q
phate).
69,70... N-K-Ca-P1/2 (sodium phosphate). 132 53.0 12.0 8 76.9 8 4. 40 A3106
73, 74 ... N-K-Ca,-L-P, (slag A)...... 107 39.0 9.0 6 97.2 8200 1. 04 5 0
177..N K C -s(lgA) ............. 15 49.0 11.0 8 525 1. 9 8.777..30 615 09
81 82... N-K-Ca-L-P, (slag B) .......-..... 96 34.0 9.0 8 9&.18 470 M8 K0 3.6.010 27,
85,86... N-K-Ca-PI, (slag B).... .... 120 42.0 12.0 8 SC 2 8 5. 28 7.. 3. 05-2.
89:90... N-K-Ca-L-Pl (SIg C)Q ..... 115 44.01 10.5 7 42.54 500 1.8 8.0 32 0410 -.3 8#
93394... N-K-Ca-P, (slag C) .............. 68 26.01 5.0 6 101A a 1.1i5 9. .0 835 "a
i7', 98... N-K-Ca-L-P, (slag D) ........... 110 43.0I 11.0 8 92.48 3.0 Ma8 65 392 .5 '1 2.0 A2
101,102. N-K-Ca-PI (Slag D) ............. 135 54.0* 12.0 8 104.8 006 .0 3.3. 4 .a
105,106. N-K-C&-L-Pj (acid phosphate).. 1111 $4.0* 7.0 8 M5.0 8 5. C 411
109,110. N-K-Ca-P (cdpopht).. 207 78.0I 18.5 8 46.086.
113,114. N-K-C&-LPj (phosphate rock).. 40 20.0 3 .0 5 91.48 '05 1.'$.59, V
117,118. N-K-Ca-P1 (phosphate rock) ..... 80 13.04 2.0 6 84.2:V A75 1.9 805 50 4, -0
.1218122. N-K-Ca-L-P1 (sodltz phos- 204 77.01 17.0 9: 12L.08 606 288 81 37800
-M 26, N K CaPI sodium hsphate).. 214 K5 0 1if.0 6 it 9
58,NK.1ri-b dsom phbs-14 37. 9.0 M T 2 a4&07
Pi 14.n;;I:,..i,:
~" ;12~s1 Iiiiil" 'ii;;dMW












141~~~~~~~~~~ 1I2 N -.1 1sdu phos %10 80 1. 828 8. 448 0. 70 890 3. .





.. a L 1 / ..ve te ...s ... .... .... .... ....... L...... ... ... U9 0k.. OW.. ... ... d...... in. 30 8 1 .



(bon~e.. ..... 8... .. ..3 "' : P M i !
Pot... TV .. #A O 'Wesh Tt w... w...... ..... .. ..pto am.................. ...... a "

SSA. ~ .h sh t) ... be) of Of ...... bar.. of ... b.a.r. of. .bar.. (.9........... 8. 4


a g N E CO x -1b 6e l t) 0 11 . .... ... ... .... .... .... ( yp
146 n.NVN 1? soiu pos 20 LO 1.0 a 68. 8 9.0t 14. 1. .60 It L*rr 91'... 6s I&C O















followed the addition of phosphate (see ,rs. I and 11). .Wh
phorio acid was added at the rate of 0.007 per cent\!PO, (Fi
soluble phosphates were the most effective. Phosphate roek "i i
least effective, while reverted phosphate, bone meal, and siagh
almost negligible influence. When phosphoric acid was
the rate of 0.014 per cent PO, (P,), practically the samIe
applied. By comparing the pots with and without liegumni%
no phosphate was added, plant growth seems to have been b
by the use of green manure. When added with the phsphJ .
green manure did not show a very active influence except in Il
of phosphate rock, when a better yield was obtained with the .u.a.l'l
legumes. I
While an increase in growth of cowpeas was brought about bj & e
use of phosphate fertilizer, there was no great regular variationrt
to the various phosphates. When applied at the rate of 0.00Q PZ r
cent PO,, the slags had the greatest influence. Applied at thersLj
of 0.014 per cent P2,O, sodium phosphate gave a higher yield t h
slags. The influence of acid phosphate, superphosphate, and
phate rock was quite marked. The highest yield in this series!r
obtained through the use of sodium phosphate at the rate of CfIOA
per cent PO,. .
With buckwheat, as with the two previous crops, a marked i -
ence was exerted upon growth by all forms of phosphate. The uii
tive effect of the different fertilizers was quite similar, that is, while
the soluble fertilizers were apparently the most effective, the differ
ence was very small. However, it may be safely said that 0014 pir
cent PO, was more effective than 0.007 per cent, while 0.021, per
cent and 0.028 per cent were still more effective.
The most important fact brought out in the second series of tests
with millet was the marked increase in effectiveness shown by the
phosphate rock and slags, which were about equal to the soluble itos-
phates. In all cases 0.014 per cent PO, produced a higher yield than
0.007 per cent. Attentions called to the fact that, when added at the
rate of 0.007 per cent P,O, the phosphate rock was the most effective.
But when added in larger quantities, the soluble phosphates still!
maintain their superiority as regards effectiveness to such an exibftl
that sodium phosphate added at the rate of 0.021 per cent







-.


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Sli. 41, Hawaii Agr. Expt. Station.
, "* _.:.-:


PLATE I.


FIG. 1.--COMPARATIVE AVAILABILITY OF PHOSPHORIC ACID IN THREE TYPES OF SOIL;
ONLY NITROGEN AND POTASH ADDED.

Left to right: First two pots, red-clay soil No. 2; second pair, red soil No. 3; third pair, sandy
soil No. 1.


FIG. 2.-INFLUENCE OF SODIUM PHOSPHATE, EXPERIMENT I, MILLET I.
Left to right: Check pots; sodium phosphate at the rate of 0.007, 0.014, and 0.021 per cent POs.


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Bul. 41, Hawaii Agr. Expt. Station.


PLATE II.


FIG. 1.-COMPARATIVE INFLUENCE OF PHOSPHATES, EXPERIMENT I, MILLET I.
Left to right paired pots: Check; slag at rates of 0.007 and 0.014 per cent P205; acid phosphate,
0.014 per cent P205.


FIG 2.-COMPARATIVE INFLUENCE OF PHOSPHATES, EXPERIMENT 1, MILLET I.
Left to right paired pots: Phosphate rock at rates of 0.007, 0.014, and 0.028 per cent P205; acid
phosphate, 0.007 per cent PsOa.




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However amo coplte ata phosphate sroie ts, wrae oftained2'8n tier
results ~ ~ egrwt weev uh cof, ithte prceirng 'crop, it the mil
M~thesame~qant as Unble, the mother how-
the turits anud the plossil to hihlmewasurded futer: Auc larger
than thos treatedithies and toleummie. if:the pot = er, hi te
After stending for ofbout n ne monthsnthe ntte sefi rell"
sAllw faThe reut were of 'g prowth; n i the reoal- of uq ib'
erospoor growffethbiv eat- phosphaitlied rtLok wasWw ied

ftt sesek ws the motimotnt result months craeop .01 Ohrsfient, '41-
tesasoi th"osphate phs est weorel moore effectie thane the, hatol

fther repeated froaildicres toheiai inabBa got of t vmes Miei h the
add ed to rainste phaco. epheriagment wit thi cropwas badoed
THoeer almost omplthe darta fo rop of niet sm'aneobane the opfbck
whesuts wenvrenlyed much:y to etemdith the -asamtcrp of thesp miet

th uncips reoalnd the pantslto whichslime was added whether largerton
esthabewen tho e trae wit lime:shat and leue..ndese pothorphitte n

relativ te avaiailt of sthepopatsaw'.&O3 S o i
IH J L4
falw h rslswrrte uprsn.M hai- aUe
y.po rwhe tsfriie ih
__r bumh O

iiiiii9
Iniiii fte hco W e dd t h.rte i cn
Phshrcad hsht
acidi th.....st.~lphs
pht okwsscn.We ple t h aeo .1- ;
goiiiioshtiiiiitiloeyfolwd yth lgs h
rok n cdpopaei h re ie.Sneoi. Tr
iiii-fposhrcai, ol aebenrmvdbyt p.
thi tneirwhiniaeih naiiyftelmei h44hze
ade orti hpopatsa'climpopae
Th lnsfo h ltto rpso iltadteCo fhik

wha eeaayeprtyt eain h mon fp6 io
aiciiieoeiiiih ol~n lotodtmde hte V 6si
eiibtentetpso hshtoue ntepopecn
tetoiheganorsrw
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_I I I` I I .1 "


N-K-Ca-L ..............................
N-K-Ca ...................................
N-K.-Cas-L .......... ....... .........
-K-Ca.....................................
N-K-Ca-L-P -/ i(slag A) ................
N-IK-Ca-P (slag A).....................
N-K-Ca-L-P i (slag B)..................
N-K-Ca-P u/ (slag B) .....................
N-K-Ca-LP 1/a (slag C)..................
2N-K-Cr-P i/r (slag .....................
N-K-Ca-L-P 1/ (slag D)...................
N-i-Ca-P i/a (slag D).....................
-I-a-Ca-P i/ ( pcd phospbate)...........
N-K-Ca-P 1/ (acid phosphate)..............
.i-. 1--LP 1/2 (phosphate rock)...........
iK-Ca-P /ra hatee rook) .............
-CS-P I (sodium phosphate)........
i-PbP i, (odium phosphate)...........
-P A) ............. ......

-a -Pi(ag C).....................

fP--Ca-P (slag IC... ...............
K-CaeP1( ------------------------
N-K-Ca-LP i(slag D)....................
N-K-Ca-P I (slag D)........................
N-K-Ca-L-P (acid phosphate).............
N-K-Ca-P1 (acid phosphate)..............
N-K-Ca-L-P (phosphate rock).........
N-K-Ca--P (phosphate rock)..........
N-K-Ca-L-P (sodium phosphate)..........
N-K-Ca-PI (sodium phospate)...........
N-K-'Ca-L-P 1 (sodium phosphate).........
N-K-Ca,-P (sodium phosphate)...........
N 11/-K 1/r-Ca-L-P (sodium phosphate ...
N i r-KI I/r--P I (sodium phosphate)....
N-K-Ca-LP 1 i/r (sodium phosphate).......
N-K-Ca-P / (sodium phosphate).........
N-K-C-L-P (phosphate rock).............
N-K-Ca-P 2 (phosphate rock)............
N-K-Ca-L-P if2 (superphosphate)..........
N-K-Ca-P IP (superphosphate) ............
N-K-Coa-,-P i(superphosphate) ...........
N-K-Ca-P i (superphosphate)-..............


Perot.

too---ss


1,2,.....
56....
9,10....
13,14...
17,18...
21,22...
28,26...
29,30...
33,34...
37,38...
41,42...
45,46...
4, 50.. .
53,54...

6, ". .




i .. -
93,94...
97,98...
101,102.
105,106.
109,110.
113,114.
117,118.
121,122.
125,126.
129,130.
133,134.
137,138.
141,142.
145,146.
149,150.
153,154.
157,158.
161,162.
165,166.
169,170.
173,174.


Per t.
0.293
.399
.250
.425
.454
.592
.392
.598
.895
.619
.333
.464
.350
.376
,.584
.300
.278
.229
.200
.578
.367
.252
.265.
.307
.443
.584
.358
.345
.666
.471
.329
.527
.189
.377
.277
.421
.510
.444
.351
.296
.388
.369


Peact.
0.121
.172
.099
.092
.192
.277
.196
.209
.173
.263
.116
.157
.135
.126
.219
.240
.179
.133
.077
.079
.108
.051
.097
.134
.143
.171
.275
.162
.172
.209
.224
.336
.153
.209
.128
.195
.260
.216
.1i69
.123
.221
.135


Perct.
0.383
.404
.413
.433
.483
.638
.503
.515
,453
.478
.488
.408
.462
.616
.472
.562
.443.
.509
.:593
.645
.518.
.598
.581
.428
.428
.617
.675
.498
.507
.494
.732
.509
.519
.538
.680
.657
.752
.650
.764
.652
.576
.682
.522


Pern.
o. m
0.085
.115
.148
S.102
.127
.122
.156
.175
.116
.115
.119
.128
.110
.202
.118
.136
.238
.152
.114
.185
.101
.099
.097
.068
.125
.346
.099
.124
.104
.188
.110
.099
.157
.244
.167
.219
.160
.246
.120
.182
.159
.139


'Iii'


ass


.3421




.849
.480





.598
.448



.340
.627


I --' ---~



















































...... ....... W. 12.7 4
0 a. 387.4 7 @.0 41.6 6.1 6 90.4 43.0 8
2L "5.4 8 57.6 29.3 &8 8 85.7 41.5 5
.. aLA 32.7 21.1 6 79.0 35.0 4.0 6 66.5 29.0 4
SI. 20. S 108.5 48.0 4.6 5 108.7 50.2 8
S80 T.9 7 930 43.2 7.7 7 122.4 42.5 8
.. ..5.5 2.. 8 101.0 46. 5.2 6 111.7 4.0 8
WC). 83.7 21.6 3 85.6 40.0 7.8 8 72.5 30.5 4
: 16.5 9.7 7 10.0 45.1 8.4 7 125.5 81.0 8
A c ) 24L2 1.5 7 80.0 36.0 L1 8 72.5 35.5 4
l P. 11.0 7.0 2 86.0 -40.5 8. 8 117.0 54.6 8
S" 9..... 95. 6.5 47 12a. 52.0 8
IWLXJA. X (acid phoa-
A.41.5 28. 7 77.0 35.0 6.2 8 66.7 33.0 4
.....n.......... 41.5 4
ik(.b.....a 17.0 10.9 6 97.0 43.2 8.3 7 30.5 15.5 8
17, a ipb
S..... O 8 4 76.0 36.0 8.1 8 17.2 85 8
...... .5 *.0 8 100 48.8 LO 8 120.7 $6.5 8
.......... 0 4. 8 0. 41. 9 8 68.5 23 4
Sv ........... 45.5 32.2 7 90.5 47.7 8.1 9 113.7 49.4 8
........... 0 39.2 8 92.0 45.0 7.0 8 115.7 52.5 8
S187,138, u a g -L-P
masha pbosphato).. 27.2 17.7 4 86.5 41.4 10&1 8 TI.0 58.8 8
w4143. m I I 2 r12%P I1
"kV5i 3-tn "Pwpheosphte).. 87.0 22.8 110.5 51.6 11.0 9 77.5 33.3 8
asMfi N-K--L-P 1 (Msodif-
a )....... 4.5 84.4 8 116.0 52.6 8.3 8 141.9 59.3 8
...... 48.2 32.3 7 113.5 50.7 9.3 8 157.2 78.0
S, ompl Mpplattn o fertl ter. s No cop.




4; C
aS........


I"





















..I III I ..I 1 Il.
1 No crop.
The first crop was planted February 2 and harvested May ., tA
second crop planted May 8 and harvested August 10, and th t j
crop planted October 12 and harvested January 66. The fil
well mixed, aerated, and dried in the air for a short time bet
plantings. : :
The results of the first series were almost completely 'vrifimy& d
this second planting. The pots to which no phosphate wasii
produced a very poor growth. All applications of pho
increased the growth, the soluble phosphates having the gnat*E
influence, while phosphate rock had the least.
The second crop of millet in this series again verified the rMeutd&
the first series with marked regularity. When added at the rate6 d
0,007 per cent P2O,, phosphate rock and the slags.were most efic
The availability of the phosphate rock when added at the ratd4
0.014 per cent PO,, was very high, but did not surpass that of sod
phosphate, and the latter, when added at the rate of 0.021 perel
P20,, produced a heavier growth than the former when added at '
rate of 0.028 per cent PO,. This apparently is further evidence n6
the more lasting effect of phosphate rock when added in s
quantities, and of the superiority of the soluble phosphates wb
added in larger quantities. I
At the same time that the pots in Experiment I were ready for.
third planting of millet those in Experiment II were also ready
the third crop of millet. In view of this fact, another comp
* application of nitrogen and potash was made in the former with
I '" -results already given, while a second application of phosphate
made to the latter in order to compare the two. The most obvi
results were the rapidity of growth in Experiment II as comp4
\ r h that in Experiment I and the increase in weight of plants AL
.._ .._i .:.....






1%


* a.


*.


a'
S


47





; .=-v.o
t.






3.s.'
ss1-~ x:
... .. "**
!'?^iit.


Bul. 41, Hawaii Agr, Expt. Station.


PLATE III.


FIG. 1.--COMPARATIVE INFLUENCE OF PHOSPHATES, EXPERIMENT II, MILLET I.

Left to right: Check; slag, phosphate rock, acid phosphate, superphosphate, and sodium phos-
phate, each used at the rate of 0.014 per cent Ps05.


FIG. 2.-COMPARATIVE INFLUENCE OF PHOSPHATES, EXPERIMENT 1I, MILLET I.

Yeft to right paired pots: Check, phosphate rock at rates of 0.007, 0.014, and 0.028 per cent P2sO.


A
S
/I

C
.j"
r:m


Z
..;. *I:.
'~;~
t ; '


". .=,






~,; ~.


*'


""V*_7


Bul. 41, Hawaii Agr. Expt. Station.


PLATE IV.


FIG. 1.-COMPARATIVE INFLUENCE OF PHOSPHATES, EXPERIMENT II, MILLET I.

Left to right paired pots: Check; sodium phosphate at rates of 0.007, 0.014, and 0.021 per
cent P2ss.


- -KIIIS E m m*ai i mimniiini ri 1 -


FIG. 2.-INFLUENCE OF COWPEAS ON THE AVAILABILITY OF PHOSPHATE ROCK,
EXPERIMENT II, MILLET I.

Left to right paired pots: Phosphate rock at the rate of 0.007 per cent Ps05 without cowpeas;
same with cowpeas; phosphate rock 0.014 per cent P205 without cowpeas; same with
cowpeas.


": .4


. .. ii




.;










of lther *6re little more, effestve


fatthat the soil used in Experimeyta T anA 11 vvs
p cacdtwo soiUle les defcient in thiA con titeuet
better mechanical texture were chosen for fuxether tests.
th& phosphates had little influence, updn plant growth,
onl on pantngws made.t. I -soil NoA 3there
'efibet, and two crops were grown in this, series. :In the
ol(No. 2),y the plants did hot stool, but in soils Nos,, I and 3
teaivestoolingy 816d for thisl reason the. number (if stools
of plants is indicated in thie tables.
(t-nn id the. pots ass ehat modiied as -ollo p
"Wi 'was fised 'inA this series, And additions -were made of
phosphate, iripotassium p'hosphate, dptsimphos,-
aspanphosphate, reverted phosphate, and bone meal.
: LCivsil No. I were.:ft seded June W8and havsed September
It (~I @ilNo. were Seeded Ju ne 23% and harvested Septem-
wmr then heated, mixed, anid replanted to millet
2, And harvested January: 11. The results axe given in

dtso soil No. I produced excellent growth of millet. re-
atfertilizer. The growth Mi the pots containing sodium phos-
p pe slightly greater than in the other pots, but this soil showed
iAMU 161 Oiy hihi viale phosphate,.
A*No. 3* pro-rod To 'be slightly deficient in available phosphoric
on an increase in plant growth resulted from all phosphate
apppaios.Phosphate rock was gain the latfecieof anl the
phaqUtes. Sodium: phosphate and superphosphate produced the
larestinreaiie, while the'results from slags and acid were very
god.Roverted phosphate and bone meal were very ineffective.
The a basic, dibasic, and tribasic. potassium phosphates were
usd J1 eterminey if possible, any influence due to, basicity of the
salt, no such relation was apparent.
T*secon millet crop on soil No. 3 gave very little information of
A Mi-aal value In this crop the plants did Lnot stool, and partly
for thisrewen the weight -of the plants was considerably reduced;
.heaw. the decrase in plant growth noted, here must be attributed
pria~fly to seasonal fUctors, although removal of readily available
phosphte may have been: a minor factor. Phosphate rock proved
to be a very inefiective. form of phosphate, and the soluble phosphates
gave the best: results
enss*-16 3











TABLE V.-Efe~ct of fertilizers on weight of crops in Experhhei _f......


Soil No. 1. SolN.3


Msilet. Millet 1, Malet 11.
t Fertilizer added.
Weight of crop. Weight of crop.Wegtocrp
Num- Numa- Nugn- Num- Num u-N -Nu-
ber of ber of berof ber of ber fbro e fbto
*Green. Dry. Heads. plants' tools. heads. Green. Dry. Heads. plants stos ed..Gen r.pet.. em&.


Grams. Grams. Grams. Gramns. Gramse. Grams.Grams.Grams.
11,2..... N--CaO-L ..o.............;........ 263.0 120.0 .28.2 7 16 16 89.0 50.5 9.3 8 ...... 8 256 1.8
5,6 ..... N-K-Ca .......................... 236.0 108.0 19.0 8 17 17 15.5 10.0 .6 4 ...... 2 380 188a
910 .... N-K-Ca-L ....................... 268.0 126.5 22.2 -8 14 14 93.0 43.5 8.5 6 -...... 95 1.
1314.. N-K-Ca .......................... 251.0 120.0 15.8 8 12 12 W1 ---------- ............ ..
1,18::: N-K-Ca-L-PI (sla A) ... ...... 283.0 129.1 15.4 8 19 19 174.0 87.5 -19.-0- 8 9
2122 ... N-- 11.2..slag.A 244.0 109.5 13.6 8 13 14 148.0 76.0 14.8 9 ...... 9 3.0 12.89
4950 ... N- K7Ca- LP,1 aci ph-os-p-h-a te). 208.0 112.0 18.8 8 11 11 155.0 83.5 16.0 7 ....... 60 2. :
5345.... N-K--Ca-P/ (cd phosphate)-.... 217.0 .93.5 11.4 7 11 10 151.0 79.0 12.7 9 .... .
5F 8... N-KC-aP/ (phosphate rock) 255.0 123.0 22.3 7 16 15 129.0 71.7 14.4 361' 1.
61162. N-K-CaePi2 (pophate rock)... 269.0 110.5 15.5 8 15 15 17.0 9.5 1.1 a ....... 3 4.9 -2,
65 6... N-K--Ca-L-Pal (sodium phos-
phate) .......................... 255.0 124.5 21.8 8 20 19 166.0 84.0 15.0, 8 7. 6
69,70- N-K-Ca-Ple (sodium ph1osphate).. 263. 0 121. 7 26. 0 8 21 22 180. 0 $8.0 14.5 8 ...... 8 465,1
73,74 N-K-Car-L--P sla A) ........... 209 10 86.0 15.6 8 13 12 179.0 92.0 14.6 a ....... n %
77,7s-- N-K-CoaP, (sag A) ............. .. 229.0 96.0 19. 6 7 14 14 161.0 83.4 11,0 8 ...... 6 4,8 24
15106. N-K-Ca-L-P (cdpohae. 236.0 97.0 15.8 8 13 12 160.0 99.0 13.2 101 6.8 558
19110- N-K-Car-P, (ai hopae ..... 257.0 100 5 17.5 8 14 14 160.0 91.6 8.0 9 7.70 0. ,a
11)114. N--a-L- (phosp r )... 258.0 102.0 15.3 8 13 11 35.0 21.1 2.5 432-
117 118. N-K-Ca-P, (phosphate rock)-... 230.0 85i 0 12.8 8 11 9 6.0 4.0 .5 15 2..i5.14.
1211122. NK-Ca-L-Pj(sodium phosphate) 284.0 103.0 16.5 8 15 13 209.0 104,8 13.1 9- 0 :-2.
125i 126. N-K-Ca-PI (sodium phosphate).. _230.0 93.0 14.3 8 ........ 8 203.0 120.0 8.6 8 1 0 0 "
1297,130. N-K-CacrL-Pj (sodium phos-
.14 10 R.5 90.8



















phate).-------------------------- 261.0 113.0 18.5 8 14 14 234.0 168.8 14.3 78
133, 134, N-K-CarP, (sodiumn phosp3hate)- 304.0O 121. 6 20. 3 8 18 18 241.0O 112; 8 15. 6 8 358 14
13F, 138- Ni -Ki i rCao-L-UP] (soda i U m
phosp~hate)........... 224.0 103.6 25.0 8 20 20. 230 -01.8 191.9 8 14 U's 45
141,142. N 1IrK112-Ca-P, sodiumu phos-
phate)................ ..... ..... 317.0 139.0 29.6 8 18 18 U41. 0. 100.9, 17.4 8 O ,,3.
145, 148 N--K-Ca-IPj ug (sodium phos- ....
phte). ........... 291 0 99.7 -19.5 9 171 16,270 1. 14.5' U.
1491150. ILa- 11/(sodium phosph Aie' 211.0 8%0 10 118 18
153; 15*. N-K-aLF (phosite reqgl). 261,0 106,1 19 38 15 :1U 94.0 v.)
." '" N O O P 4
L iii ;- I
rrr JF A -**AAin 'iiiiii .,,,,,,,,,
li:;n ; ;
i iiiiiiiiiiiiiiiiiiiiiiiiiiiiii-i! iiiii i iiiiiiiiii i iiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiii. iH iiii iiiiiiiiiiiiiiliiiiiiiiiiiiiiii iiiii=:~ iiiiii~ i ~ iiiiiiiii iiiliiiiii~ i~ iii iii iIiiiii i:iii i =i: = i i


iieiii iiiii~iiii ii iiiiiiiiii iiiiii i i iiiii ii~iiiii iiiiii iiiiiiiii iiii ii!!i ~ iiiiiii i :iiiiii i i
!il l iiiiI N i~i~ r
iiiiii iiiiiiiii iiiiiN -, ,






i i r Iiii liiiiiii iiiiiii
=:: :: I iiiiiiiiiiiiii ...














II










T-IM1 Ilet./O Oflt ,Mla
Fertiiser d77,
Wigh oforop Weght f eop. igh of roF
Num-~~~~~-7 Nu7Pm7Nm um us.Nga
..e ..... ...f h ro hro e f e fb ro
....n ...... pat.sols ed. Gre, D y eas lns.sol. had.Paie






1GrNeenP sue hopae. 25 D7 13eas 17. s stos heds Green21. DO 9.5 3. 8e ~ plats stos.h Pum*(4&
Gram. N-mCe-Ls.t (trimra.aGamGrw..esi Gmm
MS. s te)4%- .. D....ate rock ... 244.0 111.0 17.5 8 14 14 .....0 .0 .. 1 ..... .......8 38.0 -10.3a
177,178. 6 -2Pi (rimanelu 22.phos. 1 0 0 8.7 12304 1.
plpt 186. N (superphosphate).... 268.0 120.0 15.7 8 is 14 135.0 743 07 8,.... 7 8. L
1In I41. N-K-Co&I-Dl (SPriph 9 94A8 u
ph ~ ~ pht 27.......... 10.0 108.5 17.8 8 IS 13 216.0 1102.5 28:': 5. 4
phat174 X- PI au h, pbat.... 215.0 9610 317.0 8 is 1 2170.0 989.5 1180:,... a. 884.5 4
nhophaete) .......... ...... .... 258.0 111.7 17.6 7 is 12 184.0. MO:2 12.6 9:.-.. 6 78 8ML 2
177, 18.NK Pl dptsmphos-
Phto ...--............ 294.0 120.0 18.8 8 12 15 136.0 08.3 11.7' 8 ........ 8 .81.0 2.9* 8 S =F
187,188.~~~ .....L-ay .moo ....fu
phsht)............... 198.0 296.0 10.2 8 16 12 1A30 890.3 3j.5 2 ..... 1 50. 2r.1 8
18x90 w-K-D-P its nopot assiPhu'
Pb ha t U- .. ................. 264.0 125.0 23.0 8 19 15 160.0 778,5 5L9.. 8 W 1, 2U5 QS
1119.; N -KCi L P (drImp0tia'gnsium*
phsht170.......... 9.0 91.0 19.3 8 14 13 15.0 7L.5 1i 2' el 417 8. 8.
1A3Iasi. N- o-I(trimaneiu phos-,
ht).-- .................... 264.0 113.0 22.0 8 22 2D 162.0 54.7 ...... 8 ...... 8.. 36.0 20.0 a &
1870 198. N-K--Ca-L-PIs (moripotudsumph
p ophate) ....................... 180.0 89.0 18.1 8 13 12 2143.0 80.3 3.8 8 14: 3 A4. 5 20.1 3 8
197, 192. N-K-L-P i(tripoagssium hs
phumate) ................... 298.0 125.0 86.5 4 1 15 155.0 75.5, 120 78 S1. 31 30 S 20.
193, 100. N-:K-Ca-LPj (dripoagusaum phos-
Dbate) ..................... 278.0 121 .8 22. 8 t 18 18 1170R 5t o4. .. ... 8 ... ... .... W.0 oA

phate) .......................... 288.0 125.0 2.87 8 219 219 2193.0 100.0 2.0 8 10 2 39-1k 20.5 ah -










..... ........ ... ........ i i



io No.... 1.ii Soil, No. 1.



Millet. Millet 1. ii IL
N.e iie added.






Weight of crop. Wu-Nm a- eight of crop. Weigh ofcrp
ber of ber of ber of ber of ber of ber of ber of: ber of
Green. Dry. Heads. plants. stools. heads, Green. Dry. Heads.Pat.sol.has Gen r.pat.has
pots s i Gram Gram. Gram as. Gram.






phspat) .................. 247.0 122.0 24.5 8 20 2 0 176. 86.0 12.6 8 10 0 5.0 35
205,206. N- -a P (iiiiiliiiiaiiiii1 u m











phosphate)iii.......... .... 265.0 127.5 30.5 8 18 19 194.0 83.ii' 12.5 81
riiii irn: ii; iiiiiii, n~












2(erted phos
phate) .......... .... ........... ........ ........ ........ ....... ........ ........ 78.6 45.5 8.2 ......6.2
225.226 N- -Ca-i/2rev ertdphosphate) ........ ........ ........ ........ ........ ........ 75,.2 44.4 6.5 ........98 9211.8
227228 N K-C -L- l (b nemeal) ...... ........ ........ ........ ........ ........ ........ 47.0 30.5 4.0 8 8. 3 2.
22D 23. N K-c -P12 on mell........ ........ ........ ........ ........ ......... ........ 42.2 24.6 3.5 888 440 9Ag8
231232 N--CaL-P (rvered phos-
phat) ...... ...... ........ ........ ........ ........ ........ ....... & ........ 90.0 53.7 6.7 8 a6 4 2 .81

23F 28' N K-a-P (onemel)........ ........ ........ ........ ........ ..... ... ........ 31.5 M 97 1.6 5 7, 2,5 ,.7







........ ..... .... .... ..... ... ... ...... ..


... .. .. .. ... .... . .. 1 4 1 .
_gt_














































:pneu wuit me pnospnates. .i-ns son is a navy ciay type; ivo. o
iiqntains much less clay, and No. 1 the least clay. It is entirely pos-
.~able that there is a relation between the influence of the lime and the
amount of clay present in the soil. The most striking effect of the
i lime in case of soil No. 2 was upon the character of the plant. In all
pots without lime, the millet came up in clumps like grass and grew
to a height of only about 6 inches, while the addition of lime produced
normal plants.
On replanting the millt in soils Nos. 2 and 3 the results were
: soinewhat different. The lime had apparently lost its influence in
most cases, more especially in soil No. 3, which contained less clay.
,, The second part of Experiment IV was planned to determine the
;i; availability of ferrous, ferric, and aluminum phosphates as com-
pared with the other phosphates. Soils Nos. 2 and 3 were used in
: this work, the results of which are given in Table VII.
::' ** "' '' .^


';'"'
L. i: ;i; ii.il
;.i iuili
i ;.. ~~~ .iliiaPlll;lliiiIlllllll;,i;;l;;r;;i










TABLEc VI-Effec of fertilizers with and without lime.
_ rni xi :::::::::iiiiiiii:









Soil No. 1. Soil No. 2. 80l No. S.
iiiiiiiiiiiiiii iiiii iiiiiil ii ............................... .. ...







iN os i ............







Wight of Weight of Weight of Weight of Weight of Wehto
ciirop.i Num. irop. NUMi crop. Numii iOroP Num.- Crop. Num.. crop.






ber of ber of ber of ber of her of I ,. ro
plants. plants. plants. Plants. p an plnts
Green. Dry. Green. Dry. Green. Dry. Green. Dry. Green Dry. Green. .Dry.


Gm. Gra. Gm. Gm. Gm. Gm. Gin. Gm. Gm. Gm. Ga07. Gm I
13114 N-K-*L-Pi (phosphate rock) ....... 258.0 102.0 8 201.0 96.8, 8 40.0 20.0 5 32.4 17.0 8 35.0 21.1 .. 02.2 38.4
20;208
1718 N--K-Pi (phosphate rock).....-.. 230.0 85.0 8 252.0 108.7 8 30.0 13.0 6 30.8 15-.5 8 '0.0 4.0 21 V4 71.
::~~~ i lii~i::il iiii '""" "i~lii::ii iiiiiiiii ii iiii





















209)210 ..... ... ..
10;106 N-K-l-*PI (acid phosphate) ....... 236.0 97.0 8 234.0 97.0 8 117. 0 34.0 8 33.2 18.0 8 160.t0 903.0 8 170 75.2
21Y212
.si;sii~sii~iitiiiiiiiiiii iii i ii iiiiiiiii i























1i110 N-K-P (acid phosphate).......... 257.0 100.5 8 224.0 .4 8 201.0ii 78.0 S 51.3 26-i. 8 1.0.0 .. 80......
23214
11122 N-**r-EP,(abdtBfnphosphate).-...A284A 103.0 8 213.0 104.8 7 204.0 77.0 8 34.5 17.5 8. 200. 0::i104.8 S. M.7 72
15126 N--EBdu paht)...3. 80 8, MAt 111.2 8 214.0 ft 0 8 28. 9 14.6 'R 208.0 120. 0 8 9a;@ 9 2
27218
910 N-K-L ..................... ....... 268.0 126.5 8 228.0 91.5 6 46. A185 8 2:8.'7 14.5 $ 9. 0 Sk 5 8 5& 7
131 N-K ............... .............. 251.0 120.0 8 234.0 10&.7 8 32.0 13.0 7 '16. 0 8.41 4' 15.5 10.01- v: 29A8 t8V8
S1iiiiiiii
i iiiii




















...... ... .
i=~~~~~ ........i ==ii
iiiiiiii iiiiiiiiii iiiii 4

= Iigji










TO-Lit No.Irec 1.OV AR



Millet ~Mille 1I. -gh


Pertffizer added. 4CeN91e Lim9. N fe ie

Weiht f eigt o Wigh o Weight Of Weight of W o
or,*- u. rp um rP N=m rp Nun, 7=461gg W
ber of, ber Of ber of her of bro
plns ~atpat.plants. s
Gre.DGreeme DrDry Oremn D~ry.. Grimm.Dr. Green Pry. GemTy

G m. G a. O m. G m. G a.. .......G a a.G )
118 14 N K-L-s (hosp ate ock....... ....... ........... ....... .. ..... ...... 120 753 2 0 38 8 4. 278 8 17

It 7,11 ri N-K-P,(phoisphAUerock). ........ ........ ....... ....... ... ....... $... 0.6 10. 5' 81 345 1.6.7 8 26.5 14.3 $7.9 2L't
211D
1% 0 1TK-J.-P, (Adld phosphate) ....... ....... ....... ................ ... ....... 590.0 32.5 8 44.0 2.0.3 .8 01'1 8...5 U a M 7 47. 8 L

211212 194
100 11 N-K-Pi (aoddu phosphate). ..... ..... ....... ........ ....... ....... ....... $5.5 179 :. 1 4.0 20.2 a 37.0. 0. 3 n. 7.
2130214

91 12 N,-K-_L sdu ph s st)...... ........... .. ---- ....... ....... ........ ....... ....... 44.5 10.6 4 01,8 8 8 20.2 7. 8 36.0 20.3 8 55 3757

14 N.! ...................... ...... ....... ...-.... ....... ....... ....... ....... .9.1 6.0 2 (1) ()....... ........V 27.8 IC 0 a


SNo crop.





















N-K-Ca-L-P (ferrous phosphate).........
N-K-Ca-P (ferrous phosphate)...........
N-K-L-P (ferrous phosphate).............
N-K-Ca-L-P (femc phosphate)...........
N-K-Ca-P (ferric phosphate)...........
N-K-L-P (ferric phosphate)..-............
N-K-Ca-L-P (aluminum phosphate)....
N-K-Ca-P (aluminum phosphate)........
N-K-L-P (aluminum phosphate).........


N-K-Ca (check)....................... 8.5 5. 0 4 29.5 17.8
N-K-L (check)...................... .. ........ 34.9 20.0
N-~------------------------------I-------~ -----'---I----------- --'----^ ^ ~
1No croon.

In soil No. 2, ferrous phosphate apparently .had a toxic inmfl
upon the millet, while ferric and aluminum phosphate proved: '
very available types of fertilizer. They were more readily avil~lsx !
than phosphate rock, about equal to basio slag, but less readily asSim;- i
lated than soluble phosphate. .:
In case of soil No. 3, ferrous phosphate produced a good growt.i
due probably in part to the fact that this soil is more open and th'
ferrous salt may have been oxidized to ferric phosphate. Hence it k
may be said that both the iron salts and the aluminum salt are avail-
able sources of phosphoric acid, more so in this type of soil than phlo- .
phate rock, about the same as reverted phosphate and bone mea
but less than the other phosphates., .
In view of the action of lime upon the availability of the phosphate |
shown in the previous table (Experiment IV), pots were prepared f i
which the iron and aluminum phosphates were applied with ani
without lime. The results showed iron phosphates to be more avail-
able without lime in this type of soil. The opposite relations held fr
aluminum phosphate.
SAND CULTURES.

A further test of the phosphates was made in sand culture to de-
termine more precisely the action of the salts when not under the in-
fluence of complex soil conditions. Eighteen pots of silica sand were
prepared, to each of which equal weights of nitrogen and potash fer-
tilizer were applied in addition to the following, which 'were run in::
duplicate: Ferrous, ferric, aluminum, sodium, titanium, and acid
phosphates, phosphate rock, and slag. Two check pots received
nitrogen and potash but no phosphoric acid. Each phosphate pot
contained the same weight of phosphoric acid (P,O,). .


Grams.
7.0
() '
42. 5
35. 5

35.5
.. .. ... 5


Grams
3.8
..........
18. 6
16.7
15.8
16.7


1

8
8
7
... .. .. 7


Grams.
45. 5
41.0
51.5
55.0
60.5
88. 5
11.3
70.0
16.0


' r :: .ii
' ^ ;
i .i.....,i


. 21.5
17.5
85.5
28.0
81.8
55.8
5.3
33.8
9.5



































S which teact less readily with iron and aluminum. Until very recent
years this ha:tbeen the generally accepted theory among soil chemists.
1 tfhe results of more recent investigations, however, indicate that
ir' n and aluminum phosphates are readily available to plants, in
iiany ciaes more do than the insoluble forms of calcium phosphate,
an c as bone meal; slags, and floats. Recent work at the Wisconsin
I i periment Station,2 for example, has shown that 9 out of 10 plants
S tii steds made -better growth when fertilized with aluminum phosphate
| than with calcium phosphate, while 6 of the 10 made better growth
with ferric phosphate.
In view, therefore, of the uncertainty on the subject, the peculiar
' character of Hawaiian soils, and the practical importance of the matter,
I it was deemed necessary to study carefully the behavior of various
phosphates on typical Hawaiian soils.
SThe phosphates used as the basis of the preceding experiment are
,.. of commercial importance. Other phosphates were added to the
i: series in order to obtain information relative to the availability of
so .... NYw YJ k sanu on, 100o ,p. 357. Wwidn ta. DBl. 240 (1914), p. 22.

























iV J it.sLJ.U J.A LLLLCL.UtJ a Uat^caW a tALU tFAJJ.Sf pLriJC Uuj, *a Sl.in M us. Iu.5 IA IIJS4 A.
ing extent in the islands. It is prepared, by adding limo:;
phosphate.
The results of the experiments indicate that the. soluble.p11
are the most effective on Hawaiian soils,-especially those of
clay type. As already indicated, this is contrary to the cone
reached by others in regard to the application of solb le ph.
to soils high in iron and aluminum oxids. : ,....'
Iron and aluminum phosphates are readily available so..:
phosphoric acid in Hawaiian soils, the former more so in th
crop in the absence of added lime. In sand cultures the '.
phosphates surpass the calcium phosphates. Hence, since t.e .ili:
cipitated phosphates of iron, aluminum, and even titaniux ,,
available to plants, factors other than chemical combination
be considered in order to explain the apparent insolubility :of, .
phoric acid in Hawaiian soils.
That the phosphoric acid of the red-clay soils of Hawaii .e ii
some form extremely unavailable to plants is proved by e
obtained in Experiments I and II (pp. 10, 15). The soluble .ir'
phates were the most effective on the first crop. Their effective .
decreased somewhat in the following crops. The phosphate rock'# ....
least effective at the outset, and its effectiveness increased .d...
then decreased as compared with other phosphates, if the.weight of
succeeding crops may be used as a criterion. Through fernnent .s-
tion changes and chemical action the availability of the.phbpphate :
rock was increased to such an extent that the plants of the secondA. ..
millet crop to which this fertilizer was applied had a larger reserve:.

.P1







































.I. lin.a me green-manuree pots as compare wtn tnose unmanurea,
adicat ing that the fermentation of green manure and loosening of the
dpt:. assisted the millet in assimilating the phosphate rock. The same
i4 tors influence the availability of bone meal, which is greater in
itmic soils where acid-forming bacteria are present.
S...The amount of phosphoric acid present in each pot, according to
theabsolute analysis of the soil, was approximately 18.0 grams, while
hat added as fertilizer ranged from 0.19 gram (P1/i) to 0.76 gram
I(P,). The analyses of the plants show that the total amount of
phosphoric acid removed by the two crops of millet and one of buck-
wheat, in most instances is equal to that added at the rate of P/1s,
ia.n ever instances to that at the rate of Ps, and in one case to that
at .te rate of P,1 i. The third crop, which was not analyzed, was
w. iiemost stunted in growth of all the series, indicating, as the analyses
S shlow, that the major part of the. available phosphoric acid had been
removed by preceding crops, leaving only that naturally occurring
in the soil. It is plainly evident that the millet was unable to


.. .. .......
...., .... i'!:: ,,'.... .




















present, or itself acts as a source or pnosphate to the plants. Ut
The fate of soluble phosphates when added to the red-day an .
their influences upon the physical condition have been qui
oughly dealt with in previous bulletins of this station.i The iti
power of this soil for phosphoric acid has been shown toU b.e r
high and rapid that a loss of phosphate by drainage, thr.oug.h.s
application, is impossible. The fixation of the calcium phopi
greater and more rapid than that of the sodium phosphate, -but
sodium of the latter acts as a strong deflocculating agent and wd.
more completely distributed throughout the soil. This p
explains its greater effectiveness as compared with acid phoospit
which tends to flocculate the soil particles. i
Lime was added throughout the experiments on the ass~atip
that it would cause a reversion of the soluble phosphate and t'4hl
delay its ultimate, combination with the trivalent oxids. Fr- a"
the results obtained, the conclusion is obvious that a normal applio&
tion of lime is not capable of holding the phosphate in reserve'ii a
form available for the plant and, furthermore, that the benefitdei-
rived from the application of the lime, while it may be due in kiat
to its chemical activities, is primarily physical. The action is dnly
temporary, and its influence is exerted to the greatest extent in fth
first crop. The nature of its action is a flocculation of the ,la$
particles which temporarily disturb the colloidal condition in which
the iron and aluminum oxids and hydroxids exist. These compound,
together with some silica, combine to form the clay present in this
type of soil. The most important function of this flocculation is Wo
hinder or perhaps only delay the occlusion of the phosphoric acid by
the colloids. That the soil does finally return to such a state in due
time following the application of lime is indicated by the physical
condition of the soil in the pots after the third crop of millet in
Experiment II, and the further fact that it had reached a state of
apparent acidity, as determined with litmus paper. At the same
H Hawaii Sta. Buls. 35 (1914) and 40 (1915).


. .. ........ ..... -












'~~~* AM "PO0th1 Uae whAupesh inetokgoin vatite,
19 ~ ~ ~ ~ II esAaihatespite of the Arposeivo qantaikimeaf
&MU ab I nid but in, paer thO it,ma MAY OX0 hSO fUO 4tMfit
gpquat in atMqntk s f in hiuoes of tha *ip lieted by.-,the,
a-of tbae limaequireMen
tblusiton is evident that the uuavaila&liy- of, the -pbe*-
'JA the, clay soils 'of Hawaii is not due entirety totheir chem--
tittwith`UM %ma auin um s phdkphites tbut t6
cy ofa far, more complex nature, The ex eaiets -re-
is, buletn, a wel a th seof eea othpr investigators,,
*to Power of certi ,planti toa mlte'th~e peiia
og f Jwoo and alumijIum .both When aple sand cule
adwhnapled to soils4... th other. hand, it. will be
.in thiq b6',in at the. mjaj r~ t fthe phosphtso
il desexstinthe fomo rnad aluminum phos".
'ht he 94ito oo soul4hshtes results in a rapid
naion with these elements.... The, answer 0o the question why
jpj atqtassimilate the phospkates of.HawaU**an soils is probably
found in the realm. 9f soil physics, as indicated above.


} awaiian soils areuniformly:,higher, in phosphate than Inain-
and soilap b4*,-thi is. Wes availablee,: especially in the. heavy clay-

,2) "MThe uvilbltofheposphoric acid in the ferruginous-clay
soils is not: due entirelyto chemical combination but partly to physical

as(3) Phosphorid iicid should bei applied to this type of soil in-the form
*1 soluble phophates and in light 'applications at frequent interv-als
it rapid returns sre. anticipated.
(4) In most, locations it is poor economy to add bone meal or other
diffiiuitlysoluble phosphates to Hawauiian soils because they already
cowtain enough insoluble phosphate to grow crops for an indefinite
numbr ofyears provided the plants had the power to assimilate it.
(5) In wet districts (uplands) phosphate rock, bone meal, basic
slag, or reverted phosphate should be very effective, more especially
so if APPlie to highly organic soils or used in systems of diversified
agnionture where they mayy be incorporated with green manure crops.
(0) The, ovaldAility of 411. the nhoqnhate fertiliiear vanesn with the




















The chemical analyses of Hawaiianri ils by soh i.. ,
chloric acid of specific gravity 1.115 or by fusion with .od .
ate,with scarcely a single exception, show a far gre ~t
phosphoric acid in the soil than would be required for pl
Hawaiian soils are largely a product of the disintegration
lava and contain abnormally high percentages of iron and i.
Likewise, they contain high percentages of, phosphoric a. .d
spite of this fact, plants suffer from the lack of ph spori
especially in the red-clay type of soil.
In the work herewith presented, fifth-normal nitric acid, I:
citric acid, 1 per cent sodium hydroxid, hydrochloric acid'dA..
gravity 1.115), water, and finally fusion with sodium carbonate ..... ....,,
used in determining the solubility and combinations of the phosphst~p..;
While the voluminous literature regarding the action of thes-t" r..I
as means of determining the availability of phosphoric -acit l:'isr:
contradictory, in general it may be said that fifth-normal nitri4a t .
acts primarily. as a solvent for calcium phosphate, while ptr '#~' ......
sodium hydroxid dissolves the iron and aluminum phosphates. ':
In the experiments here reported, the soils were treated witli ., ...i:
solvents as follows: Digested with hydrochloric acid (specific grlii': i
1.115) according to the official method; digested with 1 per centfil i U
acid for 3 days with occasional shaking, the proportion of o :'If
acid being 1 to 10; digested with fifth-normal nitric acid. "Ow'ii
hours at 400 C. in the same proportion; digested with 1 .per -~i,
sodium hydroxid for 5 hours in boiling water in the same p p
tion, and finally digested with water for 1 week with freqaEia !l
shaking. 4. '::
SOLUBILITY OF PHOSPHORIC ACID IN POTTED SOIL. *.. ;
Following the removal of the first crop of millet on the red-clay :oi f "::
(Experiment I), samples of soil were taken from all of the 'potsl'or :
analysis. Distilled water, 1 per cent citric acid, and fifth-normal
*"ill






















































Pb- hp te rock). ...... .................................... 2.6 .00255
'.. -K I-ta -L-P ]phosphate)-............-....--. .................-- 2.8 .00715
N-K-3 t- (B& ipl phap te). .............. ......................... 2.8 .00525
-C cswla(simii pn ~ ) ....... ........... ............ ....... 4.0 .0013
t.. :-Kc L-Pdm p ...pha..................-............-. 4.2 .00741
:. -Hi -P M =bate )------------------------------------- 5.4 .0025
)---- -------------------4.OO
IL. 1 ---P. (s hiphhe). ....p..............-............ 3.2 .00481

BIB 314 38,.. :pa^T ) 5. 4 .01275
lillll: 1 .d :1-K mr Pi aOdiua)t.--.- --.. ..---. 3hophte)
S.. -.- a d la m l ha te)..................................... 3.2 .00828
.. b erok)- ----- .------- 2.4 .0025619
"A --- ----- ----- ------ ----- -----3.2 .00431

-- -... -r.. orok.. ....................... .................. 4 .0071
S ). ....................................... 2.4 .00619
H, h3'W........
in: a -2.6 .006M2
170... E (B rp )a ......................................... 6.8 .0071
S..... 173174... N-K-.C s-P .aps osph u t ............... .................... ...... .8 .00717


Owing to the high'fixing power of this type of soil, the analysis of
.th water extracts would not be expected to show any great varia-
an in solubility. Such proved to-be the case, and it is probable






















the lime added had little influence as regards combination i :
phosphate, since the acid extracted little more than a trace !: ...... ..i
phate from the soil. :... .... i:

SOLUBILITY OF PHOSPHATE FERTILIZER AFTER ADDITION TbO W:.
While the preceding data indicated a variation in the soubili.jtl
different types of phosphate, in order to study the relation:, 1.
thoroughly a series of experiments was planned, using the t4.i:. ..
soil. Nineteen portions of soil of 100 grams each were i E;. :
into large porcelain dishes. Duplicate portions of this soil I
treated with each of the following phosphates, added at the: iate4 ::
1 per cent P0,,: Acid phosphate, superphosphate, slag, phosp.tc .
rock, tripotassium phosphate, monosodium phosphate, disodi .'.ii:va ,
phosphate, commercial sodium phosphate, and monocalcium plia .::
phate. The remaining portion was used as a check. After: t :i
addition of the phosphate the soil was well mixed and saturated .wit
water, then exposed to air and sunlight to dry and weather. Satuih
tion and drying was repeated twice. Upon the third drying, aft w
about two months' time, the different portions of soil were trSio
ferred to percolators, and 700 cubic centimeters of distilled water w .
allowed to percolate through each sample. A separate analysis .j.
made of each 100 cubic centimeters of the percolate. The results a s ii
given in Table IX.















Pereelates of I0M cc. subh.

MapbO*add*LBecond
first and Fourth Fifth Sixth Svehath oa
140. third 100. 10). 100. 100.
10 0.

---- .... .... 2 16 26 38 it 21 138
...... 28 2D. 20 27 29 18 140
...... ------ 3 70 do 58 .0 1M 286
.... 86 do, 60 88 -48 21 280
.......... 2
...4 A 10 ..........62
*144 4 A4 24
... Trame. Trame ..... ..... ......... 4%.4.._. j .....
...... TrWac. 4 26 14 2 78
.... .. Trace, 4 25 16 28.70
il ........ 28 10. 22 11 7
............. 3 40 4: 3Q is 130
............... Trame. 66 60 49 20 24 227
Wpothat ....... Trame 4 -14 15 12 9 54
........... ..... Trace.. 4 16 M 6 1 61
...... 2 .. 1 7082 21. 311
.. ... .. .. 428 : .. .


70 1xbkcentimeters had' psed trugh -hesoil was

Oved rom 6 p colators and extracted with 1 per cent citric
owdjjw: to Dy3 )er method. The solubility in this solvent



JTAIx CPhosphri acid soluble in i per cent citric acid.

[Expressed in. per eent of air-dry soil.]

;,,t adt Per cMat. Phosphate added. Per Cent.


dA phsubat.- I................. 0.210 Commercia sodium phosphate .......... a 18b
.. .................... .. 0 Disodium phosphate .......... .154
.... ........ *182 Monosoditum p osphate ........... ..... .242
....... ... ........... j... .192 Do.................. h................. .198
~......... ..138 : Tripotassium phosphate................. .124
------- ------- .151 Do .................................. .122
,1,% ba rock ..................... 204 Manoeslelum phosphate ----------------- 222
j. .... ..... ... .. :.......... .202 Do. .. .. .. .. ......... .222
8ok~~h qfte........... .212 Check ...................... .019


The:-Muts ca ,- show the rapid fixation which takes place when
solulephsphaes ae added to the soil is well' as the solubility of
the hoshate~aferfixation,
Inviewo ths reslts, a further set of experiments was planned
m rdr o tuy hecomparative actio of 'non and shnnmphas-
ph~lp..If ol~ephosphates revert to nirn and almnmphos-
it isto study the solubility of the, latter. This smres

























uDo..................................................... ....... 0ra .. ,. ........,sH'... ; ....
Ferric phosphate.... .................... ..................... race. I. ..
Do .............. .......... ............................... Ta .19
Check.................................. -....................... Trace. Trace.


These results indicate that a large part of the soluble 1
does revert to the iron and aluminum phosphates. .

SOLUBILITY OF PHOSPHATE NATURALLY OCCURRING IN *
SOILS.

Table XII, showing the relativelysmall quantities of pho.*.....
dissolved out of Hawaiian soils by fifth-normal nitric adid, ,1 .
solvent of calcium phosphate, and the larger quantities solu b'i e
per cent sodium hydroxid, which is a solvent of iron aiid alit m jpB 4
phosphates, indicates that the major part of the phosphates in tl S. :!
soils exists normally in combination with iron and aluminum."

TABLE XII.--Solubility of phosphoric acid in various types of Hawaiian a s r.~. "o
..... .........
[Expressed as per cent P,. .]

Soil So0 Soi l Soil Soil Soil Soil Boil Sol i"
No. 1. No. 2. No. 3.o. 4 o.No. 64. No. 7. No. 8. No. 9. N
'
Hydrochloric acid (specific gravity
1.115)........................ 0.6770.28 0.289 2.1710.427 0.286 0.116 0.104 0.024 0.234
O U_. 6 101 7 1 0 on* O 5 .. 0. 0128.........
n-----r iav------- ntil -;,214..:..,,.:Anrrqq).) Mi I i O flln f, Am flml In


en per cen ri cIa ........... .1 5iz U W M400 .3241 0 UU0 0U ...... ...... .
Fifth-normalnitric acid .......... 007 .0024 .0018 .015 .0005 .0003 .00 03 .00 .. 01
One per cent sodium hydroxi4... ..15 .0363 .0615 .222.298 .279 .052 .055 .008 .0 1 0 1
Total phosphoric acid as deter- *
mined by fusion with sodium
carbonate.................. ...... 1.060 .670 .710 3.300 .440 .460 .240 .450 .0301 .40 .iB
Phosphoric acid in humus, per
cent ....................... 22.98 1.09 1.02 4.96 2.98 2.38 1.23 1.36 0.530 1.110 0.90,'
Humus in soil..........per cent.. 1.49 3.48 4.93 7.96 3.83 3.93 3.50 3.78. 1.690 1.680 6
..1 i
-----------------------rh .-:..ll

In selecting the soils to be tested, several widely varying types w :
chosen. No. 1 is a sandy soil high in magnesia (8.74 per cent) ad.
lime (1.84 per cent) and is the same as No. 1 in the pot experiments, I
which did not respond to phosphate fertilizers; Nos. 2 and 3 are the.


i






35

Thop(A experiments; Not 4 isavr productive silt, high
8$O per cent) and humus Nos. 5 and 6 are brown-clay soils
to the claws of clays which contain a largr amount of Himo
am;Nost7 and 8 are clay soils belongig o theclas o
ch show a higher content of lumijnuim .than iron; .No 9 is
ontaining 20 per cent titanium, about 40 per cent iron oxid,
,per coft lmiu;No. 10 lis a soil which is principally: coral
'(0mut, 90-per cent calcium carbonate); No. 11 is a sandy soil
humid ditrict and is hihin btlie(.prcent) and mag-
6.8 per cent). These 9 tyes of soils include all- the important
the islands, for, whi.Jch. reason- the data should be Of Wide
0Aion in drawing' qonclusions regarding the locig up of the
-.w.,







e a egven the table show that there included soils
chypopsess all the conditions generally. considered essential for the.
o~t phosphates. heeare'the normal conditions, such .as
iley content, colloidal clay, a"nd orgaico oudhchro
phyic-chmial bsrptin he humic conditions which pro-
biological absorption; and, finally hecmIcOUoniios
as h contet, '0,f lime, magnesium, iron, alumninum and tita-
eh, either trUg4 an'actual combination or a reversion to
As Us soluble form, influence chemical fixation. At least one or
"bly all three of the'abov'e factors may influence the maintenance
6&6fvrahle medium in the soil for plant growth, in so, far as. plAnt
growth is affectedd by the presence of a readily available source of
phosphoric acid. A relation mpy be established fromt data given in
'Table XIII ,between the chemical and physical composition of the soil.'
the' solubility of: phosphoric acid in various solvents, and its availa-
bility a's measured by plant growth.
Table XII shows, the relative solubility of phosphoric acid in all the
impotatnt. soil types of the Hawaii an Islands. Since three -of these
t"Yp, Nos. 11 2Y and 3, were used in- the pot experiments; a com-
giaison of the data will indicate the relation between the solubility
an~d the availability as measured by the growth of millet. Soil No. I
did not -respond to phosphate fertilizer, thus showing the hihavail-
ability of its phosphoric acid; soil No. 2 was greatly in need of avail-
able' phosphates, as indicated by the marked increase in plant growth
folowig te apliatin of phosphate fertilizers in all forms; soil
No.3 ws lss n sedof phosphate than No. 2, as indicated by a.
Maller: incrase resulting from the addition' of phosphate. The
other soils have not been used Mi pot experiments. TIhe results of
previous experiments with soils of the same type os certain. of those
included in T able I are summarized in Table XIII.
OIL
|O






















in the different types of soil. Fusion with sodium carb
the total phosphate content to be very high in practical
The results of the official method'of extraction with hydr
(specific gravity 1.115) throw considerable discredit upo'.i
ness as a means of determining the phosphate content of
soils. This may be attributed to several causes, chief .a
is the inability of the acid to penetrate to such an extend
period of extraction as to come in contact with any -oco e:$
or other protected particles of phosphate, and, furthermore i53.........
of ability thoroughly to decompose the basic phosphates. :,::I
aluminum, and titanium, especially the last. The obvious co
to be drawn from these results is the uselessness of determnin.i
phosphoric acid in the hydrochloric acid extract and the n.
determining the absolute phosphate content. .'
The action of weak solvents upon the various types of Hafi .:::'
soils is a means of obtaining data of value regarding the solubili .
phosphoricacid, but not regarding its availability. Neither:
possible to determine in this way whether the soil will respo i "
phosphate fertilization. Stoddardi says that, for Wisconsin -ant,
if a soil contains less than 0.015 per cent of phosphoric acid solub '
fifth-normal nitric acid, it will respond to phosphate fertile izati ..
Snyder,2 working independently, reached the same conclusion h: ":
regard' to Minnesota soils. That such a relation holds good f: ,,
Hawaiian soils does notat this time appear probable, primarily 4 !iT
cause there are too many other abnormal factors to be consider .
Soil No. 1 has been shown not to respond measurably to phospha.1f
applications, yet it contains only 0.007 per cent phosphorica
soluble in fifth-normal nitric acid, but, on the other hand, contains
1 Wisconsin Sta. Research Bul. 2 (1909). s Minnesota Sta. Bul. 102 (1907), p. 36. .


:: ''I:









allperenageofthe ota phwophorio seid disd a ARI
daesec(d o typ, cowtain ironk &and Salhmidum *hhStOe
*xcees of calemin phosphateso Oiresid, is a iniachi More
solvent than nittio acid.
hamus content of Hawaiiian soila varies between wide imiftht
to localityr and climatic conditions. Since humus is
-n the availability- of phosphoric acid, some determinations
aof.-the humus dontent-of various typesv and-also of the
Sacid combined with the humus. There is apparently no
between. the. amount of humus in the soil and the phosphate
Soothe hiaumus Stoddard.' found-that as the amount of: humus
Js uot true of Hawaiian soils, buta general irulet, it may be
that those high in lime or magnesia and humus contain ak, largo
01 of phosphoric mcid organically ojnbined., Attention is
to he ighphosphate content of soilN.14 hc h uu
22.98 per cent phosphoric, acaid. In view of the fact, that
hms been found -not to respond to phosphate fertilization and
to boe &.very low content of calthrn phosphate. as measured by
innitric acid, the conclusion 18 -evident, that the organic
aein this soil is present~ Sta eadily available form.
*'he-iso&l ha-ving the strftgest fixing power are likewise those con;-
tining phospho ric M acid in least: available form as measured by, plant
pomth and also, those contain the least. phosphoric acid soluble in
weeksolventso. Theme phosphates are only slightly soluble in citric
adnitric acids butl are more. soluble in weak alkali. The soils of
wetfixing power,: due primarily to lower clay content, are high in
time and magnesia. These soils are also hihin phosphate, and while
Isrge percentage is in' the form of iron and almnmphosphate, the
*roporion. soluble in citric acid.. is equal to or more than that soluble
*Malai.Anecetintoths -done to which attention should be
A~e, s oilNo 1. his soil is iginlmmagnesia, and humus,
# mbu was taken. from a -very humid district. The analysis shows the
=ajor :part of the calcium phosphate to have been washed out, leaving
the iroen and.auiu phosphates. This is probably similar to the
w stion of westhering agents: upon lava in the oiial Hawaiian soil
fra= in pas a result of which lime has decreased from about 10 per
cent to-l10s than 1 per cent, in the average soils. The phosphoric, acid
has decreased quite often also during this process of disintegration,
soils Nos. 2, 3t 5, G, 71 and 8 wre all clay soils, Nos. 5, 61 7, and S
wme chosen for the fact that in the two, former the hrncnen si



























tabulated in Table IX, fixation is apparently influenced by t&he
of the salt. Trivalent potassium phosphate is fixed mose a~
divalent sodium phosphate next strongest, while monovalent eopfd, a
phosphate is most soluble. Superphosphate is much morea-acs..
than the sodium and potassium phosphates, as is also acid'l:
phate, with the exception of monosodium phosphate. Theasif-*'4
indicate that the fixing or reversion of the calcium phosphate: W,..l i
less rapid than that of the sodium and potassium salts, or pori.. -:I
that the calcium salt is not so strongly fixed. But this does not ..l ,ii
relate with the availability as measured by the plant growth in ft:i
soil, where sodium phosphate was the most effective phosphate :
fertilizer. The sodium and.potassium salts were least soluble iintl
first portion of water passing through the soil, and in this they ^
feared radically from the calcium salts. This indicates the pori l
influence of physical factors upon their solubility. PhosphateI e
and slag proved to be the least soluble in water.
The solubility, as measured by citric acid (Table X), indicates thlt
citric acid only magnifies the action of water. All forms of caloiu ..
phosphate were among the most soluble, except Thomas slag (tetri' .
calcium phosphate). The solubility in citric acid is also influenced :!
by the valency of the sodium and potassium phosphate, namely,:
the monobasic phosphate is most soluble while the tribasic is least
soluble.
Somewhat more complete data are given in Table XI. The soluh
ability in water is slightly different from that given in the previous r


. .:..:..:: i ...; :.







Amtat i athodI of extreatten.i hItn bo eAf*l
4o'.pothod of percolation more nearly represtte oi
spotO inusiug several solvents was to determine
iored i', the soil by the phosphates. The data
i n potaneum phosphates, to be: readily converted into
phshates. These salts also, show a :ihsolubility
Mlacd, indicating either a remiidue unconverted
coumn 3, or a partial. conversion to the soluble calcium
-vould be the--only calcium salt possible of formation "in
Of an excesfs of HiMO. The iron phosphates proved to be
Afth-normal niitrie acid, in: fact, to a greater degree
04l6 M, salts, acid phosphate, and phosphate rock. Tryi-
iimph~osphate is,'in all solvents, less soluble than disodium'

may be said, then, that, soluble phosphates, -when added to
soils, combine wih .iron. and alminum to a greater degree
wit7 ceeuee n ol otiig a high percentage of the
But thIs Ohelmiclom bi.::o:in itpel does not explain the
Jol nature of. phosphates in. the soils,, as is shown in the
IM#agiapbtaned from both. the pot experiments and the. solubility
paignants ed in- the latter half of thisbulletin. IThe unavail-
loUdton is, brought about through .physico-chemical activities,
iPA4ntAMOM rapid- when a sodim or potassium phosphate is added,
agetaesofthe rapid deflocculation of the clay, which causes more
engplee dsseination, of the salts.
f4s a MeBan of -measuring solubility,.all solvents used are of more or
lesivaueSolbility can hardly be considered a measure of availa-
bility except Mi so far as a comparison of the solubility in several of the
solvents will indicate the form in which the phosphoric acid is, com-
binedi in the soil. -As the aboire data show, the results obtained by
$6o use of "h different solvents, are quite conflicting on certain soils.
0 At he be inn o6f this work the most plausibleter ugse
do~txplan the unavailability of the phosphoric acid in Hawaiian soils
seemed to b~e its possible combination with titanium. While it is
xodoubteodly. true that, the phosphoric acid may be present to a
certainextent in this form, which is highly inoluble, this fact is of
minor importance in explaining the low availability, although it is
perh4w. the ost serious chemical. factor. Titanium is widely dis-
tributed in Hawaiian soils, which contain, oi% the average, from
5 to 10 per cent of titanium oxid, and as much as 34 per cent has-been
found. If thiw constituent were to be considered a piefactor in
the wokilability: of: the phosphoric acid, it would be expected that
tho fit~anhinsoik would: have a high. phosphate content, dAn to reten-




































to be inactive toward other phosphates already present or
may be-added as fertilizers...
SUMMARY.

(1) Hydrochloric acid of official strength does not dissollva 7
the phosphoric acid of Hawaiian soils. To determine the
phosphate content, it is necessary to fuse the soil with soa dI
bonate. .
(2) Fifth-normal nitric acid has very little solvent action uoAb:. i,
phosphate in the soils, indicating the absence of appreciable qutan :i:::
of calcium phosphate. :...
(3) One per cent citric acid has a much stronger solvent actionA. l
fifth-normal nitric acid.
(4) Of the weaker solvents, 1 per cent sodium hydroxid i .lb
strongest, due to its action on the iron and aluminum phosphatf W':.-
(5) The fertilizer (phosphate) requirement of the soil is not .me _
ured by solubility in water or fifth-normal nitrio acid, but itmy :A
indicated by the solubility in citric acid. .


-; all


... .. jfe *









4 h h t before it is added tos Ow owjwtan,
itwsn abiity after addition, but it, may indi"

"@=bate by the soil may be in1fienced

as dteneedwith'solvents does not agree in full





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t "Ws station, underW14" supervion






















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ing seriously% misleading results. On dissolving the yellow;
tate on the paper by treating first with hot water and the
alkaline on the filter with ammonia, a larger precipitate is,
than if it were dissolved by a hot solution of ammonia.
The size of the error due to this white precipitate is in
the data in Table XV showing the difference in phosphate a
of fl2 Hawaiian soils as determined by the official method. In
series the precipitate was removed before adding the M
mixture, in another the magnesia mixture was added directly.'.
TABLE XV.-Variation in phosphoric acid content as determined by different lL: '

Soil Soil Soil Soil Soil Soil Soil Soil Boil Soil s ll .... O,
Method. No..i. .
No. 1. No. 2. No. 3. No. 4. No. 5. No. 6. No. 7. No. 8. No. 9. N0. .

P. c. P. P. c. P. c. P. c. P. c. P. c. P. c. P. C P. c. P.4 JI l.
Filtered....................0.299 0.311 0.346 0.304 0.412 0.330 0.280 0.526 0.515 0.277 0.302
Not filtered............... .395 .399 .419 .349 .596 .495 .446 .733 .824 .445 .400 ;W0f
Volumetric ................ 175 .188 .224 .227 .204 ............ .569 .514 .219 .240 ..

As indicated in.the table, the error varies from 0.073 per centiM Oi
0.309 per cent, depending on whether the white precipitate is removed'..
by filtration or weighed as magnesium pyrophosphate. The volume e.
ric method of titrating the yellow phosphomolybdate with standq
alkali does not eliminate the error, but for comparison, the dete
mination by this method is given in the table.
(42).









the eteMnation df phosphorie awid Min obis
=,led Of alicon. Mutce, in choodng Wbile
skatevatigaion o`l those showing eevtain
we lorted 1arts analyses of the soils are gvnin




#al 9011 son80 Soil sonI soil sonl Boil BodBIl sell
No,, No. No. No. No. No. No. No. No. N4o. No. NO.
1. .4. S. 6k 7. L 9 0 1 2
P. Pe. P. C. P.CP~. P. C. P. C. P. C. P. C. P. 0. P. C. P. C.
..... 1.4.84 1&.28 1& 2 L go 15.16 19.32 2& 26 25.28 OD0 25.20 30.5 30.84
M20.. 25SB.25 2.78 X01 19.55 2.176 7.03 17-43 1&.81 1.319 06
Ld...zs. 40 L40 1.S0 L20 W.20 &.00 5,40 5.20 5.00 4.2D 5.20 6.2D
rgti... ...21 MM52 M. 064 7 22 3057 ft54 20,2 20 ,65 27. 09, 8SL35 3L. 34

heins Nolul condition of hhshtsin Hawaiian soils: is.
deto physical influences, only soils of the red-clay types were
m this work. Soils Nog. 1, to 6,inclusive, represent the type of
silin wWic the almnmcontent is in excess of the
If* Nos. 7 to 12, inclusive, the opposite relation exists between. *
)RP0Iil4-1 aluminoum .7hese relationships: influence to a consider-
bokthe4 physical and chemical properties of the soil, and
44" type, that isy those nw~hich the iron is in. excess, the
fomation of the white precipitate ]is More prevalent. It should also
Ipp asatinedthat the lette. mre. also higher in titanium than the
(paer .-so this.,l4ito precipitate shows it to contain
abpat25pe pntOf iaimoid, 7-0 per cent of iron and auiu
exids, small amounts of phosphoric acid., and no silica. Hence an
urorw wilI result In {he determination whether the precipitate is filtered
Sor weighed as ..g.00iu Pyrophosphate. The only solution of
OwprobIemn is, a prmyention of the deposition of the white precipitate
4F: 4, removal Pt the. inhibiting factors. That titanium and iron,
griterlytbo former, a6re the elements most active toward its forms-
Aje .my bo seen b reference to. the table of analyses and to the
talpphoingthe weight of white precipitate deposited. The greatest
a;Per occus i those soils contiig the highest percentage of iron
aq4 tit=num but the total elimination of these elmnsin the soil
eytactwitoWut "emving traces of phosphate, is a practice impos-

M.-Aaeihod for removing siics and. tiltaium rom thie soil extract
recmmededby the Association of Official, Agricltural Chemists, is'
to evsporate. the extract to dryness -and tske up i~n Ixydrochloric WcdL








*i a i... .. .. .. i .. .. : : ..... ,| '

In ordjr t illustrate (he loss h
Elements, r.rsulting tfrowJ a v p fttO1&


taken up in hydrochloric acid, filtered, p..p0 .or A
in the filtrate, and the insol hik tii4 `n
TABLE XVII.-Composition of insoluble residue JoTmed Oqn
,... .-.. -. -. ..

soln B oil soll B -. Bo ... so .oi. 8oil. o. a I~i
No. No. No. No. N6. N oX. 0o. No.' No.
1. 2. 8. 4. 5. 6 7. 9. 10.

SP. c. P..c. P P.. c. P. P.c. P. c P. c. P. e. Pc
Total residue................ 0.27 0.24 0.14 0.12 0.12 0.01 1.85 2'S 2.32 a .W!i
Sil ...................... .23 .22 .14 .12 12 .01 .00 .00 ,00
Titanium oxid.............. () (1) () (1) (1) (1) 1.05 1.85 sQ 4.J
Iron xid........ .Tr. r... Tr. Tr. T. .18 .8 2 .18 ..
Phosphoric acid............ Tr. T. Tr T Tr. Tt .10 .7 .20 .






acid i the soil extract is precluded by the rereultin t g olll
Atmeninum ids clled to the remai le dif) ( 2 .9 .32 .59 64
the two chermiine.al t

cipitate. and indicates the primary sour ce-rof erroridtos. bei
all possibility of its usea ad method t etr nitic aid
tacidiin the soil extract is precluded by the results'on.
Attention is called to the remarkable difference in amtheron'i
Sthe two chemical types. "
After a thorough trial of several methods and modintents tte










hot plate in a covered beaker. This procedure is necessary' to' ,
elimination of the white precipitate whias success fully ectfed '
precipitation n anitric-acid solution free from cld ioric ds.
lowing method has been adopted:t shu i
To 50 cubic centimeters of the hydrochloric-acid extract t
sending gram of soil, add 1 cubic centimeter of nitric addcid ane
to oxidize the organic matter and ferrous iron. Add armoniM.t. .

and wash free of chlorids. Transfer -filter and contents to the o&tiH.W*
beaker, add an excess of dilute nitric acid, and heat to boiling oh 111k ,
hot plate in a covered beaker. This procedure is necessary to
port ions ofc the ammonia precipitat e which assumes a mcoeoida.fori.hi
boiling in an ammonia Uacal solution insoluble in cold nitric acid.
case too large an excess of nitric acid has been added, it shoul
nearly neutralized with ammonia, several grams of ammonium nit"4*' '..
added, the solution diluted to 100 to 150 cubic centimeters, and' i
cubic centimeters of molybdate solution added slowly while stirr't: ...
The beaker is then placed in a waterbath at 550 C. for fcur hd ,
Further procedure is the same as that of the official method).
I U. S. Dept. Ag, Bur. Chem. Bul. 107 (rev.), 1908. I




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UNIVERSITY OF FLORIDA

3 1262 0892 0984




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