174 
Journal of Agricultural Research 
Vol. XXV, No. 4 
Table I .—Analyses of the phosphatic materials which were used in the vegetation tests 
Material. 
Total 
phosphoric 
add (PsOs). 
Water-soluble 
phosphoric 
add. 
Citrate-soluble 
phosphoric 
add. 
A Ctrl phosphate.. T . 
Per cent. 
21. 33 
3 °* 6 3 
26.03 
17. 90 
45 - 70 
Per cent. 
14.98 
Per cent. 
17. 27 
•73 
"Rnelr nhosnihate .... . 
"Rone meal ... 
"Rasif* slair ... 
1 9 - 57 
44.27 
Double superphosphate. 
37 - 73 
1 Fourteen per cent available in a per cent citric add. 
Soil samples were taken from parts of the field that had not been 
manured or fertilized for many years, at least. From 5 to 6 tons of each 
type of soil were used in the experiments. Table II shows the chemical 
composition of the soils in which the phosphates were tested. 
Table II .—Chemical composition of soils in which the phosphates were tested 
Soil constituents. 
Soil No. 
1524- 
Soil No. 
1257 - 
Soil No. 
1539. 
Soil No. 
1578. 
Soil No. 
1716. 
Soil No. 
213. 
Soil No. 
1796. 
Soil No. 
1810. 
Soil No. 
1811. 
Silica (S1O2) . 
Titanium axid (T1O2). 
Ferric axid (FesOa). 
Alumina (AI2O3). 
Manganese dioxid (MnOs)... 
Lime (CaO). 
Magnesia (MgO).. 
Potash (K2O). 
finda (Nn» 0 ). 
Per cent 
86.17 
•55 
2.11 
5 - 49 
• 056 
.28 
•37 
•33 
.06 
.02 
. 12 
5.28 
Per cent 
73-92 
.60 
4*48 
12.36 
•35 
•27 
•25 
•54 
• 07 
.09 
. 10 
7-53 
Per cent 
97-37 
•33 
.62 
•78 
.018 
.26 
.09 
Trace. 
.01 
•05 
1*32 
Per cent 
51-32 
1.16 
11.71 
22.47 
•37 
: .30 
•i 5 
.36 
•47 
♦43 
12.66 
Per cent 
92.99 
•39 
1.80 
2. 22 
•174 
.19 
.12 
•15 
.02 
•03 
. 12 
1.88 
Per cent 
53 - 34 
■85 
12 - 45 
13 -03 
. 16 
2. 77 
8. 27 
1-54 
1.44 
•15 
.07 
6. 32 
Per cent 
54 - 4 i 
i- 13 
11.05 
20.45 
. 06 
•45 
. 62 
• 54 
. 29 
. 06 
. 16 
12. 00 
Per cent 
Per cent 
Phosphoric add (P2O5). 
Sulphur trioxid (SO3) ... 
Loss on ignition... 
Total. 
100.84 
100.56 
100.98 
101.40 
100.08 
100.39 
101. 22 
........ 
Nitrogen (N). 
C\roa mnttpr 
•15 
3*93 
.103 
.14 
3.80 
.108 
.06 
2.64 
.056 
.26 
3-64 
.176 
•05 
1-75 
.006 
.03 
. 21 
Lime requirement 6 . 
. 196 
00.272 
0.075 
a The samples were analyzed by the Bureau of Soils, U. S. Department of Agriculture, by the 
method of the Assodation of Offidal Agricultural Chemists. 
6 By Vdtch method; CaO required expressed as percentage of weight of soil 
All the soils except No. 213 are important agriculturally, and when 
planted with Citrus or pineapples are heavily fertilized. No. 1524 is a 
brown, fine sandy loam from Bayamon; No. 1257 is a reddish brown, 
fine sandy loam from Pueblo Viejo; No. 1529 is a gray sand from Toa 
Baja; No. 1578 is a clay loam from the Vega Baja-Manati section, and 
derived from a limestone; No. 1716 is a grayish brown, fine sandy loam 
from Barceloneta; No. 213 is a medium sand, ariverwash; No. 1796 is 
red clay from Mayaguez (5); and No. 1810 and 18 n are red and black 
clay, respectively, from Rio Piedras. 
