MANURING EXPERIMENTS WITH PADDY RICE (THIRD YEAR) 
19 
Increase caused 
Unrecovered 
phosphoric 
acid. 
Kind of Phosphate 
Increase 
per frame. 
1891. 
by 100 grms. 
of unrecover¬ 
ed phosphor¬ 
ic acid. 
by 100 grms. 
of original 
phosphoric 
acid in the 
first season 
(1890). 
grms. 
grms. 
grms. 
grms. 
2.95 
Double Superphosphate.. 
34 
1153 
6273 
6.40 
>1 »» • • 
97 
1516 
5810 
3-44 
Precipitated Phosphate .. 
49 
T 4 2 4 
6689 
7-53 
»» 4 » • • 
144 
1912 
4510 
6-39 
Peruvian Guano 
122 
1908 
2095 
13-07 
»» »» • • . • 
186 
1423 
1399 
5-94 
Thomas Phosphate .. 
133 
2240 
3093 
12-35 
1» »> .... 
204 
1652 
2339 
5.91 
Steamed Bone Dust.. 
I42 
2393 
3326 
11.66 
»» Î» »»•••• 
243 
2084 
2768 
5.88 
Crude Bone Dust .. 
IOI 
1717 
3763 
11.65 
jt n 1» • • • • 
180 
I 545 
3296 
6-43 
Bone Ash . 
34 
529 
1816 
12.75 
»» »» . •* 
76 
595 
1874 
6.77 
Phosphorite . 
40 
5 61 
810 
13.69 
tt •••••• 
136 
826 
363 
The action of the unrecovered phosphoric acid on the yield 
in the second season was accordingly in all cases inferior to 
that of the freshly applied phosphate in the first season ; the 
only exception being shown by the Peruvian guano which 
increased the crops in the two years for almost exactly the same 
amount. Particularly noticeable is the low action of the 
residual superphosphate and precipitated dicalcic phosphate 
which, as our results show, were converted to a large extent in 
the course of one year into an insoluble form not easily ac- 
