22 
Table VII. — Analyses of phosphatic materials used in vegetation tests with bat guanos. 
Labora- 
tory 
number. 
Material. 
Total phos- 
phoric 
acid 
(P2O5). 
Water- 
soluble 
phosphoric 
acid. 
Citrate- 
soluble 
phosphoric 
acid. 
730 
730 
750 
771 
822 
Basic slag 
Per cent. 
17.90 
21.33 
27.68 
26.03 
30.63 
Per cent. 
Per cent. 
a 9. 57 
17.27 
2.92 
Acid phosphate 
Mona guano b 
Bone meal 
14.98 
Floats 
.73 
a Fourteen per cent available by solubility in 2 per cent citric acid. 
b Sample from a mixed lot of guano from Mona Island. 
A basic fertilization with nitrogen and high-grade potash salts was 
given to all pots, the quantity being shown under the detailed results 
of the tests. One-half the nitrogen applied was derived from nitrate 
of soda and the other half from sulphate or chlorid of ammonia. 
The nitrogen was divided between nitrate and ammonia as previous 
work had shown that insoluble phosphates are more available with 
sulphate of ammonia than with nitrate of soda, doubtless because the 
sulphate leaves an acid residue in the soil, the nitrate an alkaline. 1 
With the nitrogen divided between the two forms the results are of 
more general applicability. 
Immediate efficiency of the phosphoric acid in sandy soil. — In these 
tests, the phosphates were mixed with the soil one or two days before 
planting with corn or millet. The results, therefore, shbw the im- 
mediate availability of the phosphates for short-time crops. River 
sand No. 213, with a water content of 18 per cent in the dry soil, was 
used in all cases. Detailed results are given in the following table. 
Where a sample has a letter in addition to its number, as No. 263 A, 
this signifies that 2 63 A is a subsample drawn from the same lot 
from which No. 263 was drawn. 
i Prianishnikov, D. N., Ber. Deut. Bot. Gesell., 23 (1905), No. 1, pp. 8-17. 
Vers. Stat., 63 (1905), No. 3-4, pp. 247-262. 
Soderbaum, H. G., Landw. 
