'—1_‘_‘
100
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I
I

 

SOME {ACTORS AFFECTING THE
SOLUBIUTY OF PHOSPHORUS IN SOILS

Thesis for Degree of M. 5.
Russell Hayden Austin
1 9 2 5

   

MSU

LIBRARIES
”-

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3 1293

RETURNING MATERIALS:

Place in book drop to
remove this checkout from
your record. FINES wil]
be charged if book is
returned after the date
stamped be1ow.

 

 

This Opportunity is taken
to acknowledge the many
helpful suggestions from
Dr. Li. M. EoCool
C. H. Spurway
and other rzmcbers of the
805.13 Department

' ~ - . . ‘ "V. ‘.\V .‘ -‘ r ." 'Y' ' . '. '. V ,“'
LL“ 1&4L‘JN ALRHVLLU‘J Av.“ slbLL/Digl‘i

OF .‘rliOal‘HOALu Li .90 IL.)

 

Thesis for Legree of M. 5.

Russell anuon Austin

H
‘ 4b-

N
(51

THES‘S

 

SOEE FACTOfio ArFaUTihG IRA oOLUfiLLlTY

OE lHOJEBORLe LN oUILo

The solution of the problem or insolubility of phosphorus in the
soil and of ph09phorus applied, whether the soil is acid, neutral, or
alkaline, would be of inestimatable value to the science of agriculture.
Until more is known about these factors and also .he chemical constitu-
tion of soils, the practice of phosphorus fertilization or, intact, any
kind of fertilization will continue along the uncertain route of the
past.

shen soluble phtSphorus is apglied to the soil, it is subjected to
all of the chemical and physical factors of that soil, which factors
doubtless act along varying lines or directions of force. The resultant
of these various soil factors, in reality, is the real determining factor
of the solubility of the applied rhosphorus. Of the many contributing
factors, those that have been considered as the most imyortant are the
compounds of iron, aluminum, and silicon, organic matter, the lhenomena
of adsorption, and the reaction of the soil. Until more is learned
regariing the effect ani behavior of these contributing factors, little
can be ascertained regarding the resultant of these factors. Consider-
able work has been lone ugon the problem, although the greater part of
the work has been hot-house and field plot worn interpreted in terms of

crap resronse or yields. This is very geod, and in reality, is the

93809

nv'

final objective of inve5ti5ationa1 Work in the field of agriculture, but
such methOds add practically nothing to the too meager knowledge of the
chemical constitution of soils.

In the following studies, an attemlt was made to learn something
regarding the chemical constitution of the soil. The studies and deter—
minations have been of a chemical and physical nature. First a study
was made of some chemical reactions between phOSphorus commounds and
several alkalie and the resulting effect on the solubility of the phos-
phorus in water solution was noted. in connection with these reactions,
the effect of the presence of aluminum and iron as hydroxide was studied.
Tests were made also regarding the effect of time upon the reaction. L
microscopic study orlthe precipitates formed in all of the reactions
studies revealed some imlortant information regarding the reversion of

cid phosphate to di-calcium and tri-calcium IhosIhates. Following these
studies, similar esperiments were conducted with Sell Bangles taken frOm
the profile of a light and also a heavier tyre of soil. hyperinents were
also conducted withlsilicic acid, rock flour, and the line portion of
soils in order to determine if the acquired data would coincide with the
adsorption isotherm grarh. heaction, character of preciyitates, and
phosphorus content by analysis Were the Loints corsidereu in the inter-

pretation of resultS.

mil-er inental

The behavior of acid Ihosphate, under a change of reaction only, is
best made in water solutions. Time being a factor in such reactions, the
first titrations were nade in a mininum Clause of time. Ehe hydrogen

electrote (70) was usei in waging the readings of }H values. Additions

Of altali (i or 1 cc.) were made at 5 minute intervals and the readings

of pH values were made just Irior to each succeeding aidition of alkali,
thus giving the reaction time to become sonewhat stabilised. To minimize
any outside influences a corn cover was placed CHEF the container with
Openings for the mechanica stiring device and the hydrogen electrode,
and the colonel cell, containing a yorous llug in the salt arm to lrevent
diffusion, was fitted into the corn and Kept in the solution throughout
the titration. heutral distillei water was used in all of the work. The
initial volume of these forSt titrations was LOO 00., but With the sev—
eral additions of alkali the final Volume was about too cc. The ratio
of CaH4(PO;)g to alkali was the same in all of these immediate titrations.
The end points or equivalent points are on the points of 10, L0, and 60
cc. of alkali. The Specific concentration of phosphorus was varied and
is given in the tables with the other data.

The first titration of ea54(ro4), (table 1) was made with 0.1 normal
KOH. Cahro, first appeared as a precipitate when 6.5 cc. of Koh had
been aided at a pH value of 6.1. The depression of the pH value with the

a

precipitation of Cahir‘Cl1 is shown in curve A, fig. 1, table L and curve 3,
fig. 1 contains the data of this titration repeatei with double the
concentration of solution used in the first titration; table 3 and curve
C fig.l with 4 times the concentration of solution; table 4 and curve D
fig. 1 with 6 times the concentration of solution; and finally table 5
and curve 5 fig. 1 With 8 times the concentration of Solution as was
used in the first titration. The point of precipitation of the CahiO4
was advanced by the increase in concentration of solution; the solubility

product of CaHrO4 being exceeded earlier in the course of the titration.

This earlier precipitation of CaHLO4 was accompanied by a lowering of the

Table 1.
Titration of CaHAIPCAIQ With 0.13.4KCH

0.2522 gms. CaH4(P04)2 (1.26 gms. per L) in 200 cc. neutral distilled

 

 

water
Time :cc. 0.1: pH : notes Tine oo.0.1 pH notes
Hr.minc N. KOH: : Hr.hin. N. KOH
O 2.94 2: 10 13 6.39 precipitate

5 3.08 2:15 14 6.48 "

10 3.23 &:L0 15 6.58 "
15 0.0 .29 2:L5 16 6.68 "

2~ 0.5 3.45 2:30 17 6.78 "
25 1.0 3.67 2:35 18 6.86 "
3) 1.5 4.07 2:40 19 6.98 "
35 2.0 4.77 2:45 30 7.08 "
40 2.5 5.2 2:50 21 7.L0 "
45 3.0 5.5 2:55 L2 7.32 "
50 3.5 5.75 3:00 L3 7.47 "
55 4.0 5.87 3:05 t4 7.66 "
1:80 4.5 5.97 3:10 L5 7.91 "
1:)5 5.3 6.07 3:15 26 8.L7 ”
1:10 5.5 6. 5 3:20 L7 8.83 "
1:15 6.0 6.20 3:;5 £8 9.65 "
1:20 6.5 6.2 3:50 39 10.30 "
1:15 7.0 6.3 3:35 30 10.62 "
1:30 7.5 6.39 3:4) 31 10.60 "
1:35 8.0 6.44 3:45 2 10.92 "
1:40 8.5 6.1 preciyitate 3:50 33 11.0; "
1:45 9.0 6.07 alfeared. 3:55 34 11.09 "
:50 9.5 6.10 increased 4:00 35 11.17 "
1:55 10 6.14 with 4:05 36 ll.L4 "
2:)0 11 6.20 hos 4:10 37 11.L7 "
2:05 12 6.29 4:15 3 11.33 "

 

1H value 0

Cafi4ir04ig was also treated in line manner with Caiohiz and with

the same rPOTOTtiOD of yhoslhorus to base, but in a less concentrated

.L

solution, as Ca(cfi)g is, at best, only about 0.04 nornal. The general

trend of the curve (fig. L) is similar to that obtained by titrating

CaH4(PC'4) g with K‘oii, the difference Iro‘oably be 111:; due 118.1111)! 150 the

Table 2

Titration of CaE4(£04)9 with 0.2 fi.KDH

 

0.5044 gm. CaH4(104)2 (2.52 gm. ler L.) in L00 cc. neutral distilled

 

 

water
Time :cc 0.2: pH : notes ::?ime :cc 0.2: pH : notes
Hr.Minx 3 K08: : ::Hr.;in: N HOE: ;
5 3.01 2:15 16 6.80 Ireoilitate
10 3.18 k:;0 17 6.95 "
15 3.23 2:15 18 7.08 "
£0 0 3.L3 3:30 19 7.L4 "
25 1 3.63 2:35 L0 7.41 "
30 2 4.65 2:40 21 7.61 "
5 3 5.52 L:45 L: .93 "
40 3.5 5.68 L350 23 8.48 "
45 4 5.82 2:55 24 9.65 "
50 4.5 5.92 3:)0 25 10.45 "
55 5 5.91 tracipitate 3:05 36 10.50 "
1:03 5.5 5.60 formed. 3:10 27 11.02 "
1:05 6 5.55 increased 3:15 28 11.14 "
1:10 6.r 5.61 with} 3::0 £9 11.L3 "
1:15 7 5.65 KLH 3:;5 30 11.33 "
1:20 7.5 5.68 auditiona 3:30 31 11.39 "
1:25 8 5.71 " 3:35 32 11.46 "
1:30 8.5 5.75 " 3:40 33 11.51 ”
1:35 9 5.75 " 3:45 34 11.56 "
1:40 9.5 5.80 " 3:50 35 11.60 "
1:45 10 5.83 " 3:55 36 11.63 "
1:53 11 6.02 " 4:00 37 11.68 "
1:55 18 6.17 " 4:05 38 11.70 "
2:0) 13 6.35 " 4:10 39 11.73 "
2:05 4 6.51 ” 4:15 40 11.77 "
£113 id 5.65 "

lower Concentration of the latter solution. The lrecilitate of Cah104

(table 6) is later in allenring due to the sane factor.

O)

V" -\-."D
+61U‘G 3

Titration of Cau4(£04)2 with 0.4 N hon

 

1.0088 gm.CaH4(104)g (5.04 gm. Ier L) in 2)) cc. neutra1 gistilleu
water

 

 

Time :00 0.4: pH : Hates : 2110 :00 0.4: pH : flutes
Hr.Lin: N Kbfi: : : dr.gin: N Kth: :
5 L." 2:05. 10 5. 50 Bros 11; itate
10 3.11 2:13; 11 sues "
15 3.95 2315‘ 12; 6.15 n
20 3.09 2:20 13 6.41 "
25 3:11 2:25 14 6.69 "
30 3.12 2330 15 6.76 "
35 0 3.13 2:35 16 ‘.91 "
40 0.5 3.26 2:40 17 7.08 "
45 1 3.50 2:45 18 7.21 "
50 1.5 '.97 2:60 19 7.49 "
5 2 4.70 2:55 20 7.79 "
1:0) 2.5 5.19 ,‘3uu 2.1 8.60 "
1:05 3 5.41 '3:05 22 10,14 "
1:10 3.5 5.50 precipitate 3:10 23 10.22 "
1815 4 5. £9 Fil‘IeaI‘OJ 3315 2.4 11.05 "
1:20 4.5 5.0) increasing 3:;0 25 11.13 "
1:;5 5 4.92 with 3:L5 26 11.36 "
1:30 5.5 4.90 HUB 3:00 :7 11.46 "
1:35 6 4.9 additiund 3:37 28 11.65 "
1:40 6.5 4.90 " 3.40 251 11.61 "
1:45 7 4.92 " 3:45 30 11.68 "
1:50 7.5 4.95 " 3:50 31 11.73 "
1:55 8. 5.02 " 3:55 32 11.60 "
2:0) 9 5. 2.2-; "

 

Table 4

Titration of 0364(104)g with ).6 Lurmal KOH

 

 

 

1.5132 gm.CaH4(PO4)2 (7.57 gm. per 1) in 100 cc. neutral distilled
water
Time :cc 0.6: pH : Notes : Time :00 0.6: pH flutes
Hr.:in: N KLH: :6r.6in:: 5 £65:
5 2.84 2:00 12 6.17 lrccilitate

1) 2.94 2:05 13 6.4L ”

15 3.01 2:10 14 6.59 "

2.0 5.03 2:15 15 6.78 9

25 0 3.04 2:20 16 6.93 "

30 0.5-». 3.: 2:35 :7 7.10 "

35 1 3.45 2:30 18 7.27 "

40 1.5 3.94 2:35 19 7.51 "

45 2 4. 75 It. fern-.3 but 2.. 3-3.0 2.0 7. C4 ”

50 2.5 5.11 disallears 2.45 21 8.74 "

55 3 5.19 1t.10rsists. 2:50 22 10.43 "
1:0) 3.5 4.62 " 2:55 23 10492 "
1:05 4 4.46 " 3:0) 24 11.14 "
1:10 4.5 4.41 " 3:05 L5 11.31 ”
1:15 5 4.41 " 3:1) 26 11.43 "
1:20 5.5 4.43 2 3:15 L? 11.53 "
1:15 5 4.45 " 3: 53:) 2:8 1:. 51 "
1:30 6.5 4.48 " 3:25 29 11.68 "
1:35 7 4.n5 " 3:30 33 11.75 "
1:41 8 4.73 " 3:35 32 11.67 "
1:45 9 4.90 " 3:40 36 12.05 "
1:50 1) 5.L6 " 3:45 4) 1;.19 "
1:55 11 5.78 "

 

Table 5

Titration of Cah4{kCQ)2 with 0.8 NUFLRl H05

 

 

 

2.0176 g1. Cufid(104}£ (10.)9 gm. per 1) in L1) cc. neutral distilled
ther
3156 :cc 0.8: 3} : flutes : T050 :00 0.8: ya : flutes
Hr.:in: N KVH: : : Er.gin: X ALL: :
5 2.82 2:45 13 6.37 precipitate
10 2.66 1:50 14 6.58 "
15 0 L.E9 1:55 15 6.73 ”
20 0.5 3.96 1‘ .fui’ LC) 360:2:0) 16 6.90 "
£5 1 3.33 It.fur L5 sec. L:05 17 7.05 "
30 1.5 3.79 ” " J0 " 2:10 18 7.LL "
35 2 4.58 " ” 4) " 2:15 19 7.44 "
40 2.5 4.9 " LerSiSta. L:LO 2- 7.74 "
45 3 4.63 " 2:25 Ll 5.54 "
50 3.5 4.24 " £:L0 L2 10.33 "
55 4 4.18 " 2:35 53 10.67 "
1:30 4.5 4.16 " L:4J 24 11.12 "
1:05 5 4.16 " 2:45 25 11.59 "
1:10 6 .53 " L:5) 26 11.43 "
1:15 7 4.33 " L:55 L8 11.63 "
1:50 8 4.48 " 3:00 3) 11.80 "
1:25 9 4.70 " 3:05 32 11.9; "
1:30 10 5.04 " 3:50 36 12.14 "
1:35 11 5.67 " 3:15.) 4:0 12.2.7 "
1:40 1r 6. L " 5:50 50 12.56 "

 

MICHIGAN COLLEGE

 

10

Tab1e 6

Titration of Cafi4(r0n)g with 0.04 Normal Ca(cu)2

 

0.09088 gm. CaH4(PO4)2 (2.016 gm. per L0 in 200 cc. neutral distilled

 

 

water
Time :cc 0.04: pH : Notes : Time :00 0.04: pH : hotee
Hr.Lin: N K08 : : : Hr.Lin: N 202: :
5 3.01 1:55 10 6.70 .

10 3.28 8:00 11 6.76 , ‘

15 3.40 2:05 12 6.83 Pt. iaint.

2 3.55 2:10 13 6.06 " increasing

25 0 3.60 2:15 14 6.83 "

30 0.5 3.79 2:20 15 6.49 "

35 1 4.06 2:25 16 6.42 "

40 1.5 4.53 2:30 17 6.44 "

45 2 5.07 2:35 18 6.46 “

5O ‘45 5.46 2:40 19 6. 51 "

55 3 5.71 2:45 20 6.56 "
1:03 3.5 5.88 2:50 21 6.59 "
1:05 4 6.00 2:55 2; 6.63 "

1:10 4.5 6.09 3:0J 23 6.66 "
1:15 5 6.19 3:05 24 6.73 "
1:20 5.5 6.26 3:10 25 6.76 "
1:25 6 6.31 3:15 L6 6.83 "
1:30 6.3 6.36 3:20 27 6.88 "
1:35 7 6.42 3:25 28 6.93 "
1:40 7.5 6.46 3:30 30 7.10 "
1:45 8 6.51 3:35 34 7.61 "
1:50 9 6.61 3:40 40 5.39 "

 

Time is a great factor in these chemical reactions,and the straigh-
tening of the curves, and calls for the partia1-repeating or the titra-
tions in such a manner to permit the reactions to approach equilibrium.
These chemical reactions Probably would never come absolutely to an
equilibrium, but it was thought feasible to select a time factoc of 14
Consequently several solutions were neeued in

days for this work.

I
order to determine the points deSired in the titration curves. These

MICHIGAN AGRICULTURAL COLLESE

 

(”ado 17/} that] )1.

CC.

13

. Table 7
Titration CaH4(}O4)3 with.0.l normal KUH. Time factor, 14 days.

 

0.2582 gm. CaH4(PO4)p in flank mace to a volune of 200 cc.

 

 

Flask:cc 0.1 : IrH : i-Iotes : i‘lask:cc 0.1 : 1n : L'oted
no. : N K68 : : lreciyitate : no. : 5 nos : : lreciritate
O 0 3.30 :0 L0 6.78 Cazd‘tg) 2
2 2 .82 2 21 6.81 "
4 4 5.35 083104 pct. 22 2; 7.03 "
6 6 5.2 ” more L4 ;' 7.19 "
7 7 5.31 " most :5 25 7.41 w
8 8 5.36 " less 2' 27 7.69 "
9 9 5.21 " " 2 L8 7.98 "
10 10 5.53 Ca3(104)2 29 L9 9.23 "
11 11 5.58 in no. 4 30 a) 9.64 "
12 1: 5.55 witLl 5; 5; 10.18 "
14 14 5.83 increase 34 54 10.80 "
16 16 5.95 to no. 14, 35 so 13.95 n
18 18 6.49 then 40 40 11.26 "
19 19 6.63 decoreaacs.

 

Kote: lrecilitate 111 not torn in flud&8 no. 4 to 7 until 1 or 2
hours after the ex}crihent was set up, ani UnfilO4 uii not £011
in the bottom of fla Ks until several cayd later.

solutions were yregared and aiditiond naie in titrating as is
shown in the table for each!titration. oome of the 1H values were
determined with the h;;rogen electroie (70) EHJ some with the the
guinhyirone electroqe (69). Dhe eerct ofimore time on the titra-
tion of CaH4(P04)2 (table 3) is shown grayhically in fig. 3. Ihere
is little difference between this curve and the curve of the same
titration made immeiiately at this concentration, except that the
former lies lower in the pH range. in more concentrated solutions,

in which the break in the curve when the CaHEO4 preeilitate apyears

V15

3
MICHIGAN AGRICULTURiL COLLEGE

 

0.! I1- kO/K

14

Titration of 0184(104)2 with 0.04 Normal CaiCh)2 . 2ime factor 14 days

 

Irv—”r- up- ‘

 

0.25 2 gm. 0884(P04)2 . Total volume 200 cc.
CaiCH)2 used in quantity eoual to 0.1 K 108 in table 7

 

 

Flask:ec. 0.1 : pH : notes : Flask;cc. 0.1 : LH : motes
no. : 8 K08 : : irooiyitatg no. : N K08 : : preciyitate
0 O .23 20 47.00 5.21 Ca3(104)2
Z 4.70 4.77 _ 21 9.35 5.21 ”

4 9.40 5.11 CaHPOA 22 51. 70 5.25 "
5 11.75 5.18 " more 24 56.40 5.30 "
6 14.10 5.16 " less 26 61.10 5.53 "
7 16.45 5.11 " " 033- 2 63.45 5.38 "
8 18.80 5.18 " "(10412 28 65.80 5.43 "
9 21.15 5.21 " " 2 2 68.15 5.45 "

10 £3.50 5.21 " " " 30 70.11) 5.50 "

11 £5.85 5.23 " " " 31 72.85 "5.52 "

12 28.20 5.20 ” " " 3; 75.20 5.50 “

14 32.40 5 .18 Cagfi 0 ;)2 34 79.90 5.60 "

16 37.60 5.2) 36 84.60 5.76 "

18 42.30 5.18 " 40 94.0) 6.05 "

19 44.65 5.20 "

 

is more marked , the time factor is more Lronounced as is shown by
the straightening of the curve.

The titration of 0384(104)2 with Ca( on): (table 8) in quantities
equal to 0.1 normal K08 gives a curve much different in the range of
13 f¢0n that for the K08 titration (fib.4). fhe effect of time on
this reaction is seen in centering the curve in fig. 2 with the curve
B in fig. 4,by a straight ening of the i'ormer curve. Asvery small quana
tity of a crystaline precipitate fonnad in flask n0. 4. This precipi-
tate was slightly greater in quantity in no. 5 but gradually decreased

in succeeding flasks until none was found in no. 14. 0215(104)9 first

5
MICHIGAN AGRICUL;URAL cnu E‘CE

 

.0 W," .
:- .L‘r kléstyao

Titration of Cacoq with Cad4§~04)2. iimc factor 0

 

0.3009 gm. 03303 in cash tube. Total vaiume of L3 cc. each.
0584(E04), solstion contained 21.02 .n. :0; iiter.

 

 

Tube ; Cah4(104)2;irclcrtion ; In ; .FLCl}itCtLJ
no. 3 cc. ; C3007 t0 ; ;
; ; 05541104) 9;; ; c.1404 - 033(104) 2
1 3 38 3;- 80(25 Gl‘cateat £11115.
2 6 3: g: 8.49 less
3 9 3: Z 6.42 "
4 12 331 8.54 greatest agt. ”
5 15 3:13; (3.54 less "
6 18 3312 8.4 " "
7 2 3:13} 8.L3 ” “
8 2 3:2 6.12 ” "
9 2 3:24 7.91 " "
10 3) 3:22 7.07 " "
11 33 3324- 4.67 " erStaline
23 5 c3 .5 3 .5 ‘1': . ‘18 81.381 1 aunt . "
13 39 3:35 4.13 “
14 42 333: 3.94 "
15 45 333; 3.80 "
16 48 3;4 3.70 "

 

 

ayleared in tube 7 and increased in cusitity with the increase in the
aiditions of Ca(01)2.

The effect of the solid materials as 03003, CaO, anc L50 upon
CaH4(IC4)2 in water solution was stuiies by setting up a series of
large test tubes each containing an equal amcunt of the solid material
with aiditions of a solution of CaH4(P04)3 in in reasing increments
and male to a total Volume of 50 cc. each. These tubes were allowed
to,stani for 14 days with daily shaming, at the and of which thme the

pH values were determinei with the gninhgirone electroce (59) and. a

I?

?able 10

Titration of CaO with CaH4(}O4)9 . Tine factor of 1% days.

 

 

 

0.168 gm. 030 in each tube. Total vulume of each tube to co.
031841904)9 solution containei Ll.0; Um. per liter.

 

Tube ; CaH4(IO4)2;Pr0yortion ; pH ; rrecipitates
: ; 080 to z z a

no a 3 CC. 3 CaH4(PO4) 2; ; Calif-O4 ; 08.31294) 2
1 3 3. g- 12.15 .. ea3(ro4)2
2 6 5: Q 11.83 Cafii 4 "

3 9 8: 4 6.24 " "

4 12 3:1 5.L6 " u

5 15 331:;- 5.09 " I!

6 18 331% 4.78 crystaline “

7 21 3.1; 4.50 " "

8 24 3:2 4.;8 " ‘ ”

9 27 531;:- 4.03 H n
10 as Sng- a.“2 " "

 

microscopic examination made of the solie material in each tube.

There was an amoryhous precipitate in tubes 1 to 1; (table 9), and

since it is probable that 03503 can not exist at a }h of 4.5, it must
be Ca3(PO4)2. There is also a crgataline erCiyitEté in tubes e to
16 which must be either Cau4(IC4)9 or Cahi04. It is without doubt

CaH204 in tubes 4 to 10 since Cad4tleé)g we 11 not exist at a pH of

7. It is thought that CafllOd exists in tubes 11 to 16 also and that
the Ice T“ reaiing is due to the liberated CO? from C3303 which had
r '1'. . 0 AV, ‘ ‘ n _ u "w‘ 1 _ ‘ ‘ ‘1‘ I... f ‘ ‘ ‘0” t
reacted with H3£04 irsn the Jyllttihb ut oi Len4ii04)2 into Lahxo4
and LHVC
1"3‘ 4-.
To ceniare with the C3301 results the titration was releated

using Sea. The fonnsticn of Ir eciritetes of ()3th1 ans da1(ie4)g

was very much as with the 03303, but the pH range is greater in the

18

Te 19 11

Titration of :50 With 0884(P04)2 . Tine factor of 14 hays.

 

0.121 gm. ago in each tube. Total volume of each tube 50 cc.
CaH4(P04)g solution contained 21.0: gm. per liter.

 

 

Tube ; Cafl4(P04)g;Pr0portion 3 ; irecipitaes
; .‘ 1 a; heO to : PH 8 °
no. ; cc. ; CaH4(P04)2; ; Canic4 ; 033(ro413
1 3 33.; 10.40 none none
2 6 3: 2 10.15 " "
3 9 33-; 9.50 " "
4—2 10 7.62 " '
4 12 3.1 7.32 N "
5 15 3.1g- 7.03 " "
6 18 3:15 6.73 " '
7 21 3:13— 6.58 " "
8-2 22 6.48 ' "
8-1 23 6.32 " "
8 24 3.2 6.64 " “
841 25 6.24 " "
842 26 6.14 " "
9 27 3.2; 6.07 ' “
10 31 3;2§- 6.07 " "
11 33 3:23 5.65 " "
12-2 34 5.68 " "
12-1 35 5.68 " "
12 36 3:3 5.21 n "
1241 37 5.23 " "
1242 38 5.46 " "
14 42 3.3% 4.87 " "
16 48 3,4 4.62 n "

 

titration of the Ua0 (table 10 and fig. 5), changing from pH 12, at
the beginning,to 6.3 with the addition of 9 cc. 0‘ the Solution of
CaH4(P04}p, or a change in preportion from 5:§-to 83;. There was
little change in pH until 27 cc. of the 0834(é04)? solution hao been
aided th the Ca003 titration. Again the titration was repeated using

MgO (table 11), but no precipitates were formed, which is probably due

MICHIGAN AGRICULTLHAL COLLEGE

 

73625 + (4/3/2004);

Table 12

Solubility of'PhOSphorus in‘yater Solution of 0884(104)2 When
Titrated with Ca(03)2

I

\

__.__

a

\

0.05916 gm. CaH4(?0412 in each flask (equiv. to 100 Lb. acid phosLhate

per acre). Volume of each 250 cc. Tine factor 14 0333.

 

 

 

Flask:Ca(0H)2:Proportion:P605 mgm. per : ; Precipitates
no. 3 :CaH4(PO4)2; 4109 cc. ; 3
3 cc. :to Ca(0H)9; in g 3 pH ; ;
: : :Solution:Loss : ; C8K104 : 083(FO4)2
x -- -- 13.50 --, -- -- -—
1 3.23 1: 4- 13.50 0500 5.57 none none
2 6.46 1,{ 13.43 0.07 -- " "
3 9.69 1: 3- 9.46 4.04 6.31 some "
4 12.92 1:1 7.62 5.88 6.23 “ some
5 16.15 1:13 5.42 8.08 6.31 " more
6 19.38 1.14 3.78 9.72 6.50 none “
7 22.51 1:13- 2.11 11.39 6.79 " “
8 25.85 1:2 1.16 12.34 -- “ "
9 29.07 1:24 0.17 13.33 -- u n
10 32.30 1:25 0.11 13.39 -- " "
11 35.53 1:2; 0.06 13.44 8.36 " "
12 38.76 1:3 0.03 13.47 8.60 " "
13 41.99 1:"; trace 13.50- 8.65 " "
14 45.22 1.3; " " 8.02 n 7
15 48.45 1:3; " " 9.)6 " "
1 51.68 1:4 3 ” 9.L1 " ”

 

to the fact that the phoslhorus ceupounus of magnesium are more

soluble than the phosphoaus compounus on calcium, and the solubility

product of the magnesium Com unnas have not been exceeded in these

titrations. The effect of the adoitions of Cafl4(104)2 on the pH

is not as g. at as on the 080 but is greater than on the CaCOg(fig. 5).
The apllication of discovered facts to fielu conuitions is the

goal of the soil chemist an; in orier to aggroach this goal 1n'this

work the assumption is maie that an acre 6-inches of soil contains 12

percent of moisture,on the weight basis of L,O)D,0)0 pounds, in which

21
Table 13

solubility of Phoslhcrus in Water solution of CaH4ilc4)9 when
Titrated with Ca(CH)? .

0.1183: gm. CeH4(IO4)2 in each flask ( equit. to 200 1b. acid
ghosyhate Ier acre}. Volume of eacn 250 cc. Tine factur l4 days.

 

 

Flask;CBXOH)gzkroportion;P205 55m. per ; ;
; :CaH4(104)g; ,10J1QQ. ; ; ireciyitates
no. 3 CC. :tO Ca(01i) 2; in ; PH
3 ; ;solutien;1oss ; ; 08.13204 03.311104) 2

x -- -- 27.00 -- -- -— --
1 6.46 l: —“- £5.50 1.50 6.35 none 1010.0
9 12.9: 1:-§ L0.EO 6.19 5.99 some n
3 19.38 1: g 17.30 9.70 5. 2. uOubtiul some
4 £5.84 1:1 15.79 11.21 5.96 none here
5 3;.30 1:14 13.90 16.10 6.09 ' "
6 38.76 1.1; 2.24 19.76 6.31 " "
7 45.22 1:12- 4.54 22.76 6.58 - n

8 51.68 1:2 11.68 25.6‘ 6.88 . "

9 58.14 1:33 1.69 15.31 7.20 " n

10 64.60 1:55 0.25 28.75 8.34 " "

11 71.06 1:2? 0.25 26.75 8.78 " "

12 77.5: 1:3 0.20 26.80 9.01 " "

13 83.98 1:33 not 9.19 " "

14 90.44 1:35 ialyzeq 9.43 " "
5 96.90 1.3% 9.58 " "

16 103.36 1:4 9.58 n "

 

the phosphorus of the soil, or applien phoslhorus, may become uissolVed.
A series of titrations were naie on this basis with concentrations of
CaH4(P04)2 ecuivalent to 100, £00, 300, and 400 Lounas of aciu Lhos-
yhate per acre respectively. Ihe progortion of C&H4(}U;)2 to Ca(cu)g
was the same in each series. urhlengeger flasks were usea in this
exPeriment and the volumes were 5510 to Lb) cc. each. the time allowea
for the chemical reactions in these series was also 14 days.

The end goints or equivalent points in eachgof these series occur

in flasks numbers 4, 8, and 12 of each series a;ike (tables 12 to 15).

Table 14

solubility of lhcslhorus in water oolution of Cafl4(iu4)g when

Titratei with Ca(oh)?.

 

0.17748 gm. Cafi4fiio4)2 in eachlflask (eouiv. to 300 lb. acid
Lhoslhate Ler acrey. Volume of each);50 cc. Cine factor 14 0538.

 

 

 

ElaéK;Ca{Ufi) g;1~1‘01;ortiun;l 2’05 135.21.1181‘ ; ;
: :CaH4(PO&)2: 130 001. ; ; ireciyitates
n0.; cc. ;t0 CaUTli) P3 in ; 1.11 ;
; 3 ;solution; loss; ; Cau104 ; 083(r04)2

x -— -- 40.6) —- -- -- ~-

1 9.69 : j— 36.20 4630 6.25 some none

2 19.38 1: g 31.10 9.53 5.89 none some

3 19.07 1: 3 26.00 14.50 5.79 - "

4 38.76 1:1 21.00 19.50 5.82 " "

5 48.45 1:1fi- 15.41 £6.09 5.96 " “

6 58.14 1:15 10.19 30.31 5.45 n "

7 67.83 1.12 5.44 35.06 6.37 ' "

8 77.52 1:2 1.39 39.11 6.48 ” "

9 87.21 1:2;- 0.23 40.57 7.13 ” '
10 96.9) :2; 0.06 40.44 8.68 ' "
11 106.59 1:23» trace 40.50- 9.11 ” "
12 11602. 133 N H 902.], I! II
13 125.97 1:34 " " 9.52 “ "
14 125.66 1:35 not analyzed 9.55 " "
15 145.35 1:32 9.60 " "
16 155.04 1:4 9.75 " "

 

In flask number 4 the equivalent proPortion of CaH4(PO4)9 to Ca(0H)2

was 1 : 1, in no. 8 1:2, ans in no. 12 1:3. CaH?O4 was found in

the bottom of flasks 3, 4, ani 5, aha Ca3(P04)2 in flasks 4 to 16 with
the amounts increasing with the increase in the amount of auditions of
Ca(CH)2, in the titration of CaH4(P04)? equivalent to 10) pounds of
aciti phosphate per acre. If the concentrationisaoubled (table 13)
very much the same results necesecureu except that the precipitateon
even the greats r concentrations used

occured earlier in the series.

behaves in the Same manner (tables 14 ans 15).

Table 15

Solubilflty of Bhosphcrus in deter oolution of CaH4(£O4)? ahen
Pitrated with Ca(DH)2 .

 

0.25664 gms. CaHA(P04)2 in eachlflask (equiv. to 40) pounus acid
phOSphate per acre). Volume orieach 250 cc. Tine factor 14 says

 

 

 

F1ask;Ca(OH)2:ProP0rtion;P205 mgm. per : ;
; :CaH4(PO4)2: 130 c . g ; Precititates
no. ; cc. .to ; in ; 3H :
g ; Ca(CH)2 ;soluti0n; lose; ; CaHiO4 Ca3(£C4)2
X -- -- 54.03 -- -- -- ~-
1 12.92 13-; 41.38 12.62 5.79 some none
2 25.84 1. g 69.64 14.16 5.77 none acne
5 56.76 3 1 54.96 19.06 5.67 " more
4 51.68 1:1 26.19 27.81 5.70 " "

 

Cn analyzing for 1hcfilhorus in solution in the clear liqui¢ in
each flask of these 3 ries Large; iiirerenccs were found. The amount
of Ihos;horu3 in solution decreasei with auditLons of oa(oa). ans the

decrease is very maraei as the reaction aplroaohes the neutral goint,

the Solubility being very 105 in the alaaline solutions. in the more
concentratei solutions the earlier ayyearance of a 1recipitate was

scoomfaniei by an earlier urn; in the curve or the LH values (fig. 6);
while in the alkaline range, the 1H curve for the ucre Concentrates
solutions was higher in the 13 Scale. Bhe reaction and the amount of
Ihselhcrus in the solution was greatly inflaencel by the quantity of
Ca(0§)9 aided.

11);: anti 10(L11)3 tU‘V'CtiLCI‘ “with 6&1lean the

7‘

In a titrat on of a(

,- .

010633 of EG(CH}3 ircsent nade the stuiy of Irecigitates aifficult. The

uantity of yhoslhcrus taken from the solution increased with the audi-

-. ~ ~ \ a . - . .. , .
tions 01 0834(10472 but the increases were not in IYuLUFtion to the

M‘CH'GAN AGRICULTURAL cm. LFGE

 

 

Table 16

solubility of lhosphorus in water Solution when Ca( Ch)9 and 16(LH)3
Together‘are Titrated Jith a Solution of Cah4(E04)9 containing
6.5 gms. CaH4(P04)9 per Liter.

 

25. cc Ca(“H)9 and fr M3113 recilitatee 10(CH)5k in quantity equiv-
a

 

 

alent t0 2). Of 1:119 C&( UH) 2 Ti 3 placed. in 93.011118 “ (2111.0 1!; 115157;}.
Fla :CaH4(1704)? Ir01_orticn; Lgu. 1305 Ler 100 cc. 3
110.; CC. :CBL VII) 0.. t0 3
; ;Ie((;)3 t0; aided ; in 3108s ; pH
; :CaH4(104)2; ; solution; ;

 

 

1 5 1.93-4 7.10 0.20 6.90 6.93
2 10 1.5: g 14.10 0.56 13.64 6.71

3 15 1:9. j- 21.30 5.35 15.91 5.63

4 20 1:;gi 28.40 11.54 16.66 5.60

5 25 13;. 3— 35.50 19.46 16.04 5.55

6 30 1.9319 42.60 36.63 16.97 5.61

7 35 1.3: $6 ..70 30.06 19.66 5.56

8 4o 1:;.: 56.60 37.66 12.12 5.46

9 4 1.9.3; 63.90* 45.09 18381 5.39
10 6: 1.9.19 71. 0 51.6; 19.16 5.34

‘ i

magnituie of the aiiitions (table 16}. Ihe inrve of titration beains

4

at 1H of 6.9 and 610166 acenward with the 3111:1913 of oaa4ggo4)? (£15.

.4

The titration of Cafi4ifo4)9 with CaCOS, in concentration qeuiVal-
ant to 20) Ion: Hi of acii phosyhate yer acre, as biven in table 15, was
peleated with the aisition of ie{tn)3,in amounts eguivalent to one-half
of the Cah4(104)2 used, in one series and Al(.h)3 in the saz.e xrolor-
tion in another series. These results showed the influence of the
Iresence of Al(Ch)3 and 10(Ch)3 upon the solubility of the ghoslhorus
Qt 010317 and 18) and ugsn the reaction (fig. 8). uhe re “1(01), "as

present, 1633 Ca(oh)9 was reouirei to raise the ,5 of the solution to

26
MICHIGAN AGRICULTURAL COLLEGE

in

  

F/dsks 7+ ('4 f/v/qu/z.

M'CHIGAN

97
~
AGRICULTURAL COLLEGE

 

cam/y.

Flak: +

fable 17

solubility of Ihceihorus in water solution of Cah41104)2 containing
‘ 1": I V-.V -1 ‘. .. ""‘ 7' "" -'.'1 c o a 1
18(Ch)3 5941’5403t to fi'vJL L"1““:(1'V‘1J2' Time 14 cage.

 

0.11832 gs. Cah4(104)2 (equiv. to 200 pounce of acii LhosLhatu ler

"6

acre). fetal volume was 660 cc. 25.66 mgm. retoh)3 to each.

 

 

ilask;Ca(0h)gglroportiongngm. 3205 yer 130 cc.; IE ; Ireciritates
no.; cc. :Cah4(ic4)2; ; ;CaKiO4:Cas(iC4)2

; ;Fe(0n)3 ; in solutiun; loss ; ;

: ;Ca(0ulg ; a z :

 

000) 13930 2 000 . -" -- -- --

0.0) 1:9:0 25.47 5.53 5.36 none none
. 6.46 1:131; 21.86 5.14 6.;4 scue N

12.92 1.9:; 17.14 9.66 6.24 none Sume

19336 1:L:9- 13.65 13.17 6.0) " More

250 8'1 13:331. 9 0 99 170 01 60 10 H H
32-30 1 F:1§« 7.10 19.9) 6.60 w «

C3u303~30301$>02hbhlc>§<

 

36.76 13;: g 4.33 2;.68 6.49 " "
45-25 .;.1; 1.66 25.04 6.81 " "
51.66 1.9:2 0.3: 26.68 6.95 n n
58.14 131153 0.12 26.68 7.57 " "
1 54950 1:1:25 -- --. 8.25 " "
11 71-16 1.9.2;— -- -- 6.77 " "
12 77.52 1:9:0 -- — 8.86 n n
15 85-98 132:0; 0.11 26:89 —- " "
14 93.44 1:9:51- 0.04 “6.: -— n n
15 96.90 1.;33g 0.06 26.94 -- '~ n
16 103.J6 1;;34 -- - -- M u
the neutral Icint. 10(6L)5 hai sane influence ulon the }h of the
mixture but the raise in {H 043 net as great as it was where the Altoh)3
has rrczent. In the presence of leioh)3 2 egnivalehts of Ca(Cfi)° were

\
required to raise the 13 of the hixture as high as 19 eoulvqlents of

Ca(Ch)2 raised the 1K in the Iresence cf 41(ch)3. After the reaction
hai passed the Ioint 0f the acuition Of the seconi efiuivalent of the
Ca( 2);, which is the £1011 of 95 where Ca3{164)2 exists in the greatest

quantity, the effect of either Al(;h)1 or 16(6h), was not nearly so

marked.

Table 16

Solubility of Ehoeghorus in.water solution of Cafi4(iud)2 containing
AltCH)3 Squivalent to one—half of the Ceh4iic4)2 . Bine 14 “£33.

 

Iv

0.1183 gm. CaH‘(IO4)2 (equiv. to Le) yoxnds of acid ph061hnte Ier

acre). Total Volume ass :03 cc. 0.15664 U16 Al(bL)3 to each.

 

 

 

ileek;Ca(cH)2;Proyorticn; 653. 12D5 ter 13» cc; In ; rreci}itetes
no.3 cc. ;Cafl4(fod)2; ; ;
; ;to 6616313; in z ; ; Casio4;Ca,,(io4)p
; ;to Ca(0h)?; solution ; loss ; 3 ” N
' X 0.00 1:030 27.00 3-]- -- -- ~-
0 .0.00 115:0 26.25 0.75 4.26 none none
1 6.46 l:fl:3 21.86 5.14 6.49 90me "
2 17.92 1r%r% 16.24 10.76 6.57 none some
3 19.36 1.6.4— 11.66 15.14 6.47 " "
4 250 84 13%;]. 8.71 18. 29 6o 78 I! H
5 32.30 1.§:14 4.60 22.20 6.76 H "
6 36.76 13%.1‘ 3.61 23.39 7.52 n n
7 45.22 1:6:12- .75 66.25 7.35 n u
9 56.14 16§=3% .62 26.36 7.69 n u
10 640 60 1 £15327% 0 31 26o 69 8. b7 " H
11 71.06 1.25.2.5 .30 26. 70 8.94 " "
12 77.52 1.6:3 .16 26.62 --- u n
13 63.96 1.4.3; .12 26.66 --- H n
14 90.44 1.§.3§ .15 26.65 --- n n
15 96.90 1r%:5£ trace 27.00- --- " "
16 103.36 17%:4 n u ___ n n

 

The effect of Fe(CH)3 and Al(cH)3 upon the Solubility of CaH4(10;)o
was studied in 8 series where each was used alone. The concentrations
were reduced to an equivalent of 50 pounds of acid phosphate per acre,
with the proportions of the CaH4(PO4)2 to the Ye(OH)3 or the Al(0h)3 of
l to 0 up to l to 430 in tense of equivalents. In these series the
Fe(0fi)3 was found to have a greater influence upon the solubility of
the phosphorus, causing it to become less soluble , (tables 19 and 60),

and also the Fe(OH)3 increased the pH of the solution more than the

8

Table 19

Effect of Fe(01i)q on the dolubility of PhOSphorus in a deter oolution
0f 0384(PO4)90

v

0.02958 gms. of CsHA(PO4)2 (equivalent to 50 pounds of ECid yhosphete
Per acre). Total volume of each flask was 250 cc. Tine 14 days.

 

 

 

Flask; 56(Ch)3 ;}r0portion; mjm. P605 per 100 cc. pH ; Irccipitaees
110. ; 37218. ‘ 0511141904) f: g ; (38.1110433-
; ;to Fe(0h)3; in solution; loss ; ; 063(10A)2
O 0 130 6.67 —- —- -----
1 0005013 134 2.71 3,96 6009 i8<05)3
2 0.10)£6 138 1.67 5.40 6.88 obscured
5 0.20352 1:16 0.12 6.55 7.0) other
4 0.40114 1352 trace 6.67— -- lreciyitetes
5 6.60156 1:48 " " 7.19
6 0.80108 1364 " " --
7 1.0026 1.3633 not 6115131161. -- Bee
8 2.005: 1:160 7.66 note
9 3.0078 lngO 8.04
10 4.0104 13520 8.07
11 5.0130 1:400 _-

 

Kote : Tests were made for iron nith KCLJ, with very reint test Ior
irtn in clear solution in no.4 an: Slightly increasing to no. ll,

but there was only a shall smount even in no. 11.

“(0103 did (£15. 9 ).

In the foregoing 'titrations of 0634(104)2 with alkalies the

02121104 is formed when the pH is raised above 5.6 by additions of
Ca(0h)?. in the next titration presented a nearly saturated solu-

tion of C3fi204 was titrated with Ca((§)2 in the same manner as the
0984(EC;)2 in the 10) round sci; Ihcsihste equivalent PCtOTtCu in
table 12. The titration of 06K304 with 06(Dh)2 forms 063(lc4)2
which is insoluble and precigitates fr0u the solution as is shown in

table 21. The curve of :the 1H values of this titration rises tram

31
MICHIGAN AGRICULTURAL COLLEGE

 

Alla/d. or Feb/l),

’VIV4/CI115

Table 23
Affect of A1(CH)3 on the dolnbility of ihosyhorus in a Water bolution
0f CaHdUO4 2.

 

_ .
n. oi C65 (104)“ (eosivalent to 50 pounds of acid lhosrhate

 

 

 

0.02958 g; g
Ier acre). Tots volume of 250 cc. 'n each flame. Time 11 days.
112-6; Al(0£)3 ;lroportion; ugh. Egos Ier 100 cc; ;}reci}itates
; ;Ca}14(PC/.t) o; ; 1.111 ; _
no. ; gels. ; to Alfie-AT“ in ; ; ;'-.36.h'1’04 083(1‘04)?
; ; ; Svlutiun ; 1099 ; ; A
X 0 1 z 0 6.67 -- -- --
1 0.05656 1 3 4 5.50 1.17 5.64 excess cf
2 0.07512 1 3 8 6.55 2.12 5.59 A1(Lh)3
5 0. 462 1 3 16 5.45 5.24 6.55 mace
4 0.29248 1 3 52 1.53 5.14 7.57 other
5 0.65872 1 g 48 0.60 5.87 7.41 precipitates
6 .58496 1 x 64 6.40 6.27 7.51 obscure
7 0.7312 1 3 60 0.15 6.52 7.29
8 1.462 1 z 160 0.06 6.61 7.50
9 2.1556 1 g 24’ 0.05 6.62 7.66
10 2.9248 1 g 320 trace 6.67— --
11 3.656 1 x 433 " " -...

 

pH 6.5 rather abrultly upward to ebmve pH 10 (£15.10). As might be
exyected the £5 curve for the titration of Ca"704 with Ca§oh)2 lies
above the curve of 18 values in the titration of CaH4(EO4)2 with
06(08)?.

The curves of IE values thus far presented have some goints of
resemblance and each has Loints different. A 160 of the e are

grou;ei together on the sane sheet for direct ocularisonifid. 11 ).

Cd
01

fable

10
H

Titration of Cahi0A with Ca(t§)2.

 

0.04358 Qua. Caflloa in solution in each flask. Total volume 250 cc.
Thne factoe of 14 days. Bike factor 14 gaygo

 

 

 

}1ask; Catohiz 3rr0portion; ham. P.05 per100 003 LB 3 irecipitates

no. ; cc. 30(125'04 t0 ; g ;
3 ; Ca(tn)2 ; in ; ; ;Ca§204;CaSIP04)2
; ;; geolution ; 1033 ; ;

A 0 130 8.43 -— -- -- ~-

1 3.23 lgfi- 6.18 2.25 6.49 sone none?

2 6.46 1.; 3.83 4.60 6.52 nene some

3 9.69 135- 2.78 5.65 6.69 none more

4 12.92 1:1 0.80 7.63 6.86 " "

5 16.15 131% 0.15 8.68 6.89 " "

6 190U8 131g 0.12 8.51 7.65 " "

7 22.61 1:1? 0.15 8.88 8.57 " n

8 25.84 132 trace 8.46u -— " "

9 29.07 132% " " 1).£8 " "

 

Two soil profiles and a very acii sandy surface soil were
selected from which to secure samples of soil Ior a continued
Study of {heaphorus fixation uyon a Soil medium. The procedure
of study was as near as possible like the foregoing studies.

The soil in 100 gram portions was placed in jelly glasres.
The soil had been passed through a 2-mm. mesh.sieve. Bhese were
given varying treatments of CaO and made to Optimum moisture
content with neutral distilled water. These soil mixtures
were stirred daily for 7 days, when equal additions were made

to each of the soil samlles, at the rate or 200 pounds of acid

' 54
MICHIGAN AGRICULTURAL COLLEGE

 

F/aJks + (4/0/97),

 

 

o:
0:

Table 22
Hater Joluble PhOSphorue in Acid -aan1y Loam when Treated with Acid

Phoephate and 0&0.

 

5.68 fiEfih CaH4(}04)2I was added to each culture (equivalent to L00
pounds of acid phoSPhate yer acre).

 

‘

igau P29: 3 1‘205 3

 

Culture; CaO mgm.3 CaO lbs 3 mgm. P205 3
3 3Ler acre 3 aided 3 soluble in3increase3 pH
no. 3 3 3 3 250 cc.HpO3 over 3
3 3 3 3 chBCk 3

X "" O 00 EUR ""“" 50 59

0 3.2 0.987 0.695 5.70

1 " 0.67) 0.068 6.13;

E. " ‘r- -" 6.00

3 " 0.692 0.060 6.49

4 " 0.552 0.100 6.55

5 " 0.310 0.078 6.60

6 " 0.050 0.118 6.77

7 0.462 0.26) 6.69

8 . " 0.560 0.118 --

9 J0 0613 “ 0.L70 0.008 7.05
10 1:13 3.570 " 0.386 3.155 7.1;;
11 110 39;? " 0.31) 0.078 7.;2
1: 120 4:85 " 0.085 0.160 7.54
13 100 4642 " 0.550 0.118 7.6;
14 140 1 4999 " 0.425 0.190 7.69
15 150 5.356 " 0.462 0.230 7. 76
16 16) 5714 " 0.1.1:. 0.:70 7.90

 

rhoslhate per acre, and the whole almowed to stand for another luriod
of 7 days with stirring each day. At this tine they were transierred
to wide mouth bottles w;th £50 cc. of neutral distilled water, Shaking
for 1 hour on a mechanical shaker, and then allowed to stand for 7
days. The liguid was then careiully Jourud off, whirled in a centri-

fuge to make clear, and llaced in erhlenneyer fia¢Ks to each of which

water soluble IhOSrhorus in Liami Loam A; horizon when Treated with

4

Acid phosIhate and CEO.

 

5.68 8E5. Cnfi4iro4)2 was added to eaci’culture (ecuivalent t0 L00
younds cf acii Ihoslhate yer acre).

 

 

Soil 3 CaO mgm.3 CaO lbs. 3 hwflh 1:05 3 mgu.1205 soluble 3
Culture; 318r acre 3 added 3 in 250 cc. 830 3 pH
3 3 3 3 3increase3
3 3 ; 3 3 over A 3
X 0 -- 0 0.115 -- 5.31
0 0 -- 3.2 0.507 0.092 5.01
1 10 357 3.2 0.247 0.132 5.3
2 2‘ 714 3.2 0.570 0.255 5.51
3 30 1071 3L2 0.347 0.232 5.49
4 40 1458 3.2 0.310 0.195 5.64
5 5 1785 3.2 0.547 .232 5.74
6 60 2142. .502 0.3110 00193 P'-
7 70 2499 3.2 0.232 0.117 5.93
8 80 285 3.2 0.155 0.040 5.98
9 90 3513 3.2 0.077 -- 5.91
10 103 3570 5.2 0.077 - 6.16
11 110 3927 3.2 0.170 0.055 6.26
12 120 4285 3.2 -——- -—- 6.24
13 100 46'2 3.2 0.140 0.025 6.56
14 140 4999 3,2 --- —— 6.49
15 150 5356 3.2 0.215 0.10) 6.55
16 150 5714 3.2 —-- --- --—

 

which was added 1 cc. of a nearly saturated solution of 25004 to
cemllete the clearing of the solution. After Stanging over night a
a setermination of phOSIhUruG was made on the solution frog each
flaSK. The reaction of each solution was determined with the guin-
hydrone electrode (Ed).

I

The results with the acid sandy loan soil \tab1e LL) indicates

in Liami Loam A3 Hurizén When fireated nith

(I)

hater ooluble 3hoaghoru

Acii Ehoaghate and CeC.

 

5.683mga, CaH4(LOA)2 was auded to each culture (eiuivelent to L0)
rounds Of 331:.phoayhate.per acre.).

 

than. lgcs3iLcrcaee

 

.5011 3 33.0 11.3... 3 0&0 1'08. 3 111.3111. iTD5 3 3 ..
Cuiture; 3 ler acre 3 n dcd 3 cluble 3 ever 3
3 33 3 3in 250 CC3'check 3
a ; z ; Water 3 ;
h 0 -- 0 J.156 -- 6r;
0 0 -- 3.2 0.115 - 6.23
1 10 357 3.2 0.077 - 6.45
2 20 714 3.2 ).170 3.015 OoUu
3 33 1771 3.2 ).l£5 0 6.06
4 40 14L8 3.2 0.207 ’.352 7.35
5 50 1785 3.2 0.277 0.112 7.25
6 6) 214; 3.2 0.24 0.092 7.37
7 70 2499 3.; 0.;0J 0.345 7.52
8 83 2857 3.2 0.170 0.015 7.65
9 93 3Ll3 3.2 0.12; —- 7.73
10 110 3570 3.2 0.155 0 7.83
11 110 392 3.2 O.L47 0.392 7.90
12 120 .285 3.2 9.232 0.377 7.98
13, 133 4542 3.2 -v- -- --
14 140 4999 3.2” 0.155 0 7.99
15 15) £35 3.2 0.077 -- 6.07

l

little excelt that the soil is Bktcemely retentive of aciu Ihosihate,
unless it can be interpreted htat the auditions of 0&0 reduces the
quentity of {hosrhorus in solution.

The results iron the A; an; A3 horizors, which are ecid, and the
o horizon, which is alkaline, of the ziani Loam'édll tenu to indicate

a les degree of solubility of the phoelhorue in this 8011 than in the

Other 30113 Studied (tabled 24.5 351254 and .25).

39

Fable 25
Hater Joluble lhoa; horus in Jim..i Loam C hcrizon "hen freoteo with

Acid iMi sth to axii CaC.

 

5.68 men, CaH4(P04)n Jes adieu to eegh culture (eguivalent to 200
Iounis or acio IhosIhate Ier acre.).

 

Soil 3 CaO man. 3 CaO 153. 3 rwwn £305 3 mam. P3053increase3 IR
culture; 3 Ier acre; auded 3“oluole in; over 3
no. 3 3 3 3250 CC.n D3 check 3
X 0 --- O 0.088 -- 8.06
0 0 --- ".2 0.13; 0.044 8.10
6 60 2142 ".° 0.114 0.026 6.22
16 160 5356 3.2 0.191 0.103 8.41

 

The kox Joil profile was also selecteo for these stuuies. The
results which are given in tables 26 to 30;are very much the same
as in the other soils. The virgin surface released less of the
IhosIhorus into solution than the cultivated surface. more Ih03phorus
was found in solution in Yo: C horizon than in anv of th'e other.
The reactions of these soils as treated are Ilotted in gig. 12. Dhe
results obtained in this set of experiments with the Soil profiles
do nor warrant any definate conclusions because of the fluctuations
and small dii ‘fercnces aiwoi them. In oroer to aIIreach fielu condi-
tions the ouantitiee cf Ihos‘ Ihoius taaen franLUuitmmemanatione were
too small and hence the experimental error became IroIortionately
too larg‘ e to be able to get satiSfectory results.

The jhcory of ausertion in connection with Ihoslhorus 115a stion
in soils is receiving much attznticn at the Iresent tine Iarticularly

in the study of soil colmoids as well as ;n nan; other fielie of

Table 26

hater Holuble lhosIhorue in 103 oaniy Loan Cultivated ourface “hen

Treated filth Aciu Inuirhatu ani Can

 

5.68 mgm. Caiid(1~04)9 was aaied to each culture (eguivelent to 200
Iounis of acid IhesIlhate Ier acre}.

 

 

Soil 3 030.;§i. 3 CaO lbs. 3 Lgm. 196 3 Lgiu 13053increaae3 13
culture; 3 Ier acre; aiuei 3 soluble in; ver 3
no. 3 3 3 325) cc. 830. check 3
X 0 —- 0 0.252 -- 5.89
0 0 —- 3.2 0.257 0.025 6.06
1 10 3:7 3.2 0.299 0.067 6.64
2 20 714 3.2 0.263 0.061 6.61
3 30 13"1 3.2 0.293 0.061 6.70
4 40 1428 3.2 0.291 0.159 6.72
5 50 1765 3.2 0.283 0.061 6.69
6 60 2142 3.2 0.267 0.025 6.99
7 70 2499 3.2 0.216 — 7.14
8 8 2657 3.2 0.227 0.125 7.09
9 90 3213 3.2 0.227 0.025 7.33
10 100 3570 3.2 3.25 0.025 7.39
11 110 3927 3.2 0.257 0.025 7.50
12 120 4265 3.2 0.690 0.068 7.46
14 140 4999 5.2 0.273 0.0é1 --
15 150 5556 3.2 ~r- --- 7.78
16 160 5714 3.2 0.293 0.061 7.63

 

41

Table 27
Mater doluble Phosphorus in 103 dandy Loam Virgin ourface when

Treated aith Aciu lhosphato ani CaO.

 

 

 

$.68 mgm. CaHA(P0;)2 was audeu to each culture (equivalent to 200
pounds of acid ph02phate per acre.).
Soil 3 Ca0 mgm. 3 CaO lbs. 3 mgm. 2205 3mgm. P205 3increae 3 pH
culture; 3per acre 3 auded 3soluble in; over 3
no. 3 3 3 1250 00.8203 check 3
X 0 —— 0 2.780 -- 5.84
0 0 H— 3.2 0.880 - 6.35
2 20 714 3.2 1.293 - 6.50
4 40 1428 3.2 1.130 - 6.48
6 60 2142 3.2 0.720 - 6.54
. 8 so 2857 3. 2 0.177: — 6. 52
10 100 3570 3.2 0.620 - 6.61
12 120 4286 3.2 0.570 - 6.86
14 140 4999 3.2 0.770 - 6.94
16 ‘ 3 2 0.680 - 6.84

 

Table 28
Hater Soluble Phosphorue3Fox dandy Loam AZ Horizon uhen Treatea With

Acid PhosPhate and Gao.

 

5.68 mgm. CaH4(r04)2 was squad to each soil culture (equivalent to

20) pounds of 8011 phosphate per acre.).

 

 

Soil 3 CaO mgm. 3 CaO lbs. 3mgm. P305 3mgm. P905 3increase3 18
culture3 3per acre 3 addea 3soluble in; over 3
no. 3 3 3 3250 00.8203 check 3
X 0 -- 0 0.308 -- 6.80
0 O -- 502 00437 00129 6073
1 10 357 3.2 0.463 0.155 6.78
3 30 1071 3.2 0.386 0.078 7.11
4 40 1428 3.2 0.566 0.258 7.23
5 50 1785 3.2 0.463 0.155 7.38
7 70 2499 3.2 0.437 0.129 7.60
8 80 2657 3.2 0.453 0.145 7.63
9 90 3213 3.2 0.412 0.104 7.75
10 100 3570 3.2 0.412 0.104 7.86
11 110 3927 3.2 0.360 0.152 7.88
12 120 4285 3.2 0.720 0.412 7.93
13 130 4642 3.2 --- --- 7.96
14 140 4999 3.2 0.391 0.063 8.00
15 150 5356 3.2 -—- --- 8.08
16 16) 5714 3.2 0.350 0.042 8.18

 

43

Table 29
Hater Soluble Ehosphorus in Fox handy Loam B Horizon when Treated

31th Acid Encephato and CaO.

5.68 mgm. CaH4(PO4)9 was added to each Soil culture (equivalent to

201 pounds of acid phOSphate Ler acre).

 

 

doLI 3 0&0 ngrq CaO lbs.3mgm. 1205 3mgm. 1705 3incrcase3 p5
culture; 3 per acre; added 3soluble in; over 3
no. 3 3 3 310) gm 90113 Check;
K 0 -— 0 0.494 —— 7.16
0 0 -- 3.2 0.546 0.35; 7.10
1 10 357 3.2 0.463 -v- ‘ 7.23
2 2 714 3.2 0.628 0.134 7.40
3 so 1171 3.2; 0.579 0.155 7.55
4 40 1428 3.2 0. 72 0.278 7.67
5 50 1785 3.2 0.716 .222 7.70
6 60 2142 3.2 0.618 0.124 7.60
7 7) 2499 3.2 0.643 0.149 7.97
8 80 2657 3.2 0.705 0.211 7.87
9 9) 3213 3.2 0.443 -- 7.94
l) 103 3570 3.2 0.515 0.021 8.03
11 110 3927 3.2 0.463 - 8.07
12 120 1185 3.2 0.386 - 6.07
14 14.) 4993 3.2 Oo‘tl; " 801;)
16 160 5714 3.2 0.283 - 8.13

 

‘

44

Table 30
Jater boluble lhosphdrus in for gandy Loam C Horizon “hen Treated

Jith Acid Ph09phflt6 and 0&0.

 

5.68 mgm. Cah4(PO4)2 was ad1ed to each soil culture (Qquivalent to

:0) pounds of acii phosphate rer acre.).

 

 

 

13-011 3 0210 123,711; 08.0 lbs.3zx.gl.1. 1205 31.13111. 1:05 311131‘UaSO 3 PE
culture 3 added 3 Ler acre. added 3soluble in3 over 3

no. 3 3 3 3100 53.8011; check 3

K 0 -- 0 0.154 -- 7.85
0 0 —- 3.2 0.459 0.335 7.7.
1 10 357 3.2 0.479 0.325 7.85
2 20 714 3.2 0.577 0.423 8.14
3 30 1071 3.2 0.469 0.335 8.17
4 40 1428 3.2 0.479 0.325 8.26
6 60 2142 3/2 0.607 0.453 8.26
8 80 285 3.2 0.592 0.483 8.2
10 130 357' 3.2 0.582 0.428 8.35
12 12 4285 3.2 0.668 0.514 8.31
14 140 4999 3.2 .* 0.62 0.474 8.43

16 153 5355 3.2, 0.649 0.495 8.29

 

771‘_—____——V__

45
M'CH'GAN AGRICULTURAL COLLEGE

M»? C9”? C40

 

46

Table 31
affect of H26103 on the qolubility of Phos;horus in water colution

of 0aH4(IC4)2 of several Concentrations.

 

 

 

 

 

Flask; mgm. P005 per 10) cc.3m*m.P2053 3 Ca per 250 cc.
: ’ L 4. 31083 pbr3 pH : z :
no. 3 original; final; 10393 flae'. 3 3original3fina1 31099
1 8 7.68 0.14 0.35 4.33 -- -- ~-
2 12 11.79 0.21 0.53 4.15 -- -- —-
3 2 23110 0.90 2.25 3.65 —— -— ~-
4 64 62.07 1.13 4.83 3.34 45.04 41.00 4.04
5 128 123.96 4.04 13.10 3.11 90.07 63.75 6.32
6 192 166.10 5.90 14.75 3.14 135.11 124.50 10.61
7 320 313.46 6.54 16.35 3.10 225.19 202.12 23.07
reaearch. The cauasion for the addorption 180th n1 for solutions is

written (72),

um“ : x3
in which A is the amount adsorbed by 3 units of solid adsorbing
agent, C is the concentration of the solution, K is an adsorbent
conStant and n is also an aieorbwnt constant. The approximate
accuracy of the formula has been Shown by Ereundlich (73).

A series of GbPEPLmGXLB were conducted with 523105 and a natural
silicious deposit,cmmuomly called rock flour, which had a reaction of
4.9 pH. Ten gram samples of the solid were placed into ernlenneyer
flasks containing 250 cc. oi.solutione of Ca34(}04)? of several difier—
ent concentrations, shaken constantly and vigorously for 10 minutes
and allowed to stan1 over night. fine final concentrations of phos-

phorus were deternined and the results, A/M and C plotted and the

47

r";

Table 32
Effect of ”Rock Flour" on the Solubility of PhOSphorus in water 6

Solution of CaH4(P04)2 of deveral Concentrations.

 

Flask31mm.1;2053rz.51r1..13?0531351111205 31:15:11. £20IS 3 12:31.1. 12053 1;};
no. 3per 100 3rer'250 31er 100 cc.3per 250 cc. 3per 10 31h;
. cc. 3 cc. 3 final final 3rock flour;

3

I
3original3originalg loss 3

 

1 2 5 .95 2.38 2.62 4.28
2 4 10 2.09 5.24 4.76 4.16
3 8 20 5.50 13.74 6.26 4.08
4 12 30 9.02 22.54 7.46 3.84
5 16 40 12:30 30.76 9.24 3.96
6 24 60 20.02 50.05 9.95 ’ 3.76
7 32 80 27.79 61.47 10.53 3.59
8 64 160 56.98 142.45 17.55 3.47
9 128 320 118.22 295.55 24.45 3.34
10 192 480 179394 449.85 30.15 3.24
11 320 803 306.66 766.65 33.35 3.17
12 640 1610 614.80 1537.00) 63.00 --
13 1280 3230 1247.60 3119.00 81.00 --

 

curves compared with the adsorption isotherm curve;

The results from 826103 on the solubility ofiphosphorus in the
water solution 01§CaH4(EO4)p , and also with the rock flour, (tables
31 and 32, and figs. 13 and 14) somewhat approach the adsorption
isotherm curve.

This study was repeated using soil particles as the adsorbing agent.
A 500-grEm sanple oi the acid sandy loam was thoroughly shaken in
water to cause deihoculatdon and,after standing for 1 hour, the suSpen—

sion was poured off, continueing the process until the water remained

48
MICHIGAN AGRICULTURAL C01_LE"‘.E

 

3’3

.1
g
E
E
Q
s:
i
3

MICHIGAN AGRICULTUQAL COLLEGE

 

1 \
y\$ 3’3 '25

{/1444 lflfi ¢C-

777M V10

6:

[IS

Table 33
sffect of Different size Soil Particles on the Uolubility of lhosphorus

in Water Solution of CaHA(P04)2 from the stsndpoint of Adsorption.

 

 

 

Sample no.3 size of 3Rate yer acre3 Lgm. ygos Ler 156 cc. water
3 particles 3on 53) an. 3
3 3 soil 3 added 3 final 3 loss
flLL‘LJJlu S A
10 colloid 50' 40 13.55 26.45
11 clay 530 40 5.40 34.60
12 sand a silt 600 40 13.2“ 29.75
20 colloid 1)); 60 36.66 44.15
21 clay 1303 80 5.90 64.10
22 sand & silt leO 80 37.05 42.95

 

nearly clear. fihis soil suspension was passed through a super centri—
fuge thus soIer ating the soil haterial which collected in the cylinder
with the lirger size Lartgbles near the inteae, and the finest larticles,
distributel along the sides of the cylinder. Ehe portions of the
soil thus secured, namely, he finest particles from the centrifuge,
termei colloid, the less fine yarticles from the centrifuge, termed
clay, and the bulk oi'the SOD—gram sample, mostly hostly sand and silt,
were placed in solutions of CaH4(P04)2 equivalent to 500 pounds of
acid phosphate per acre. A second set was also set up in solutions
of double this strength. These were shaken constantly and vigorously
for 10 minutes, allowed to stand over night anl the Phosihorus concen—
tratiins determined. '
There was a marked loss of phosrhorus from the solutions (table 53)

in each case, but being much greater yer unit adsorbing agent for the

Table 34
Adsorption Cf Phosghorus By The line lortion Cf A Very Acid dandy

 

 

 

 

3 3 3 3
ElaSK no. 3mgp.trfiQEL§er 3 lingl_concentrztiiugn.12063

3 1'30 CC. 3 25;) CC. 3.'"L;‘..1 :05 1.81‘ _ 15113301‘ {.50 3 1,11

3origdnal 3origihal 310) cc. 3 250 cc. 3cc. loss 3

3 3 3 3 3 3
l 24 60 9.9? £4.95 5.05 4.16
3 64 160 45.03 112.57 47.43 3.96
5 192 480 163.92 409.80 73.20 3.57
6 3:3 833 254086 71:015 67oé5 5.47
cclldil and clay as they Wuiu only a very shall iLrt of the original
513 grams of soil. There lrobably was not over £3 grass of the clay

and colloid crtizns thus obta-ncd.

IJ
:7
0
*fi

iner Iarticlesof the soil were scieratcd fr;: other Iortions

r
H:
Y0
C
H
Fl
0‘
4
1
(I)
Dw—

'.'- p" r‘. '. '3 ‘f‘ . "-" -v n-vt‘ “ . .~ '7‘], 4
asking icr a .rurt C-LO, using use brmld oi soil in 363 cc.

V

of water and allowing it to settle ior 2 ulnutcs and then louring off

25) cc. of the susLension , which contained about 5) grams of the

fine soil {articles, into erhlenmcyer f133fis. To the_rlasgs thus
yrerared was addwd CaH4(}04)g in varying amountS. «hen the Cafi4iiv4)2

had been given time to dissolve, the the flaszs were :hhgen constantly
and vigorously for 10 minutes , allowed to stand over night and the
final IhOEIhQFUS concentrations determined.

The acid sandy loam soil, and the.32 hurl; n of the Liahi Loam

soil, which wee acid, were uuei in this exlerinent. Jhe data (tables

3able 35
Adsorytion of Phosrhorus by he Fine portion 3f the AL Horizon of

the Xiani Loam

 

 

Flask; Original concentration3Einal concentration; Loss 3

no. 3 I332. I506 1,8? 3 £111. loDE 381‘ 3 1181‘ {.50 3

3 100 cc/ 3 L50 cc. 3 13) co. 3 L5J cc. 3 cc. 3
1 £4 60 10.33 25.82 24.18
2 32 80 11.86 29.65 50.35
3 64 160 35.36 88.43 71.63
4 128 3:0 88.14 220.35 99.65
5 192 483 133.48 333.70 146.30
6 330 810 £60.l0 650.25 149.75

 

34 and 35) were plotted a: shown in figures 15 and 16. flhey do not
have any great resenplence to the a_sor}tion isotherm curve although
a general resemblence in shape to that curve existS.

The data in table 16 were ylotted to show the adsorption curve.
This curve (fig. 17) also somewhat resembles the adsorption isotherm
curve.

to general conclusions can be drawn fr0m these curves in view of
therfact that chemical reactions are probably present in many cases in
these soil Studies, and any very close adherence to the adsorption
isotherm probably would not be obtained in the presence of chemical
reactions. However, where there is a solid- liquid interface there
probably is adsorption and with reactible contounds'also present there
Irobably is chenical reaction, both of which are aoubtless functior;ng

in the soil.

MICHIGAN AGRICULTURAL COLLEGE

'1

.vufidV gIan 31%»: MU

 

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I v

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o >y4—o.¢—.¢- -. 0“ v owv—o-o-o- O‘Ht-O-Ot. o-+y—>v<-¢4o .¢->H++—47¢- ‘6‘OO+-Hr'—rvo~¢qqfi- .- -.«o.- ...-oo-oo-L-o~-v;o‘~ o-O-co-vooo 9
A- L; L LL A .1144; A A A A A; 11.1. i i A; A l A A A 1 AA A

.
13 § '9: x. ‘Q ’3 ‘3 UtrmHIMhh-JQUI- M~.§I
’7 ‘ ... m (‘ §~ M
\ \ §
\
- ,N-l

 

 

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warn/”0

  
      

IO

1.4L.

55
AGRICULTURAL COLLEGE

 

For 100cc. .

3-03’

7n1m.

(‘1
(I)

Conclusions

The 3011 reaction, if no other factors Prevailed, would uuubtless

a:

3.:

:3

C?
:7
w

I O

C

’4
F1
0

be a very ingortcnt factor in the solubility of Ihosrhcru

.

rcvcrtee to CaLkO and

(.4 J

In the yresence of a base the Cad4\;04)2 i
even to 033(EC4)2 eerenuing on the mnennt and nini of bases LTCRCDC

or the reaction of the Leiiun.

4 is llLCQA at abeut tn of 5.6 or above

The fornaticn Of Cnth

doleniing on the censuntraticn of the Inoekhorus coulounds of calcium.

niceseive concentration. force the Cafii04 out or soluticn by exceeding
its solubility yrcinet. in an alnfiline sail this r‘vcrsicn cf lhoe-
Ihcrts is r5111 {16)(39). flowever in terns of crop reslcnse, the

reverted EHd lrecijiteted lhcslhetes are more available than the
raw rocx Incarnate (LL).Theee results tend to show that CahiO4 Should
be a more economical form of lhoslhorus fertilizer than the Cafi4ii04)?
because of a probable lower cost of lroiuctien, as less H;u04 is
reguired in its Ireyaration from roea lhosbhate, and hishcr percent
of Incephorue.

Lime an soil reaction can not be the deternining fcctor in the
solubility of Ihospnorus in SuilS as is shown by the work on acid

‘orus.

soils in which there was narkei retention of the aleiea thee U
qurway (66) found some 5Cii Soils very retentive of allliea lhceth'us
when alpleed as acid Thee hate.

Comlcnnds of iron (11) ani aluninum (1;) have long been considered
res onsible for the insolubility cf lhcslhurus in soils 3}“ earecially

in acid soils. Very little wcrk hns been done to determine the chasi—

cel behavior of these componnis tcward comlounde of phOSphorus as

relation to the solubility of the phosphorus. The conclusions that
have been commonly advanced (42) have been based on crop reopense.

In the titr ations with Fe(CH)3 and dl(oh}3, he reaction changed.
with the increase in lawn)3 or Al(oh)3 present, and there was a rise
in the {H and a decrease in the phOSphorus in solution; in other words
the applied phOSphorus is more soluble in acid solutions when ie(OH)3
or AHOH)3 are present.

The adsorption curves secured in these esperinents do not conform
chosely enough to the adsorption isotherm curve (721173) to warrant
any positive conclusions. oince Chemical reactions are, without
doubt, present in soils, and since their effect on adsorption is not
known, but where there is a solid-liquid interface it is known that
adsorption does take place to some extent, it is warranted to conclude
that adsorption is one of the factors effecting the solubility of
phOSphorus in soils.

Lactors affecting the solubility of phosphorus in soils are not
few in number. Those studied in this paper are active and there
are probably many others. Further studies of these factors and their
behavior under varying conditions will undoubtedly add much to the
meager and much, needed knowledge of the chemical constitution of

soils.

(1)

(4)

(8)

(9)

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7

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-.r-‘ -‘ ‘A‘ I

l 0‘ "n‘» ....“-

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r- . F!“ ‘1 ! An’f"
01-08 00, a: -8. Co “a 17, .2in-

..Ao

do

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try, Bull. 107, revised.

 

65

(72) Freundlichi 1909. Kapihlarchemie, 147.

(75) Freundlicht 1907. Zeit.phys.Chem., 57, 385; 59, 263.

 

"I7'11iiii'iiiiii’iiii