184 
Journal of Agricultural Research 
VoL XXV, No. 4 
It is apparent from Table VI that none of the phosphates varied in 
efficiency directly with the lime requirement of the soil. On the whole, 
floats was far more efficient in soils with high lime requirements than in 
those with low requirements, but there is no exact correspondence between 
this measure of the soirs acidity and the efficiency of floats. 
Lack of correspondence may be due in part to the fact that the efficien¬ 
cies of all the phosphates are expressed relative to the efficiency of acid 
phosphate. The table would in such a case merely show the effect of the 
lime requirement properties of the soil in altering relative efficiencies. 
The effect on absolute efficiencies—that is, on the quantity of phosphoric 
acid required to produce a given increase in crop—can not be judged, 
since the experiments with the various soils were carried on at different 
times. Moreover, the absolute efficiencies of the phosphates would 
doubtless depend upon the degree of phosphorus deficiency in the soil as 
well as upon other factors. 
EFFICIENCIES OF THE PHOSPHATES AS AFFECTED BY LIMING 
The degree to which liming affected the efficiencies of the different 
phosphates can best be seen if the data given in Table V are presented in 
another form. Table VII shows the effect of liming on the efficiencies of 
phosphates, the efficiency of each phosphate in the unlimed soil being 
taken as ioo and in the limed soil as relative to ioo. 
Table VII .—Effect of liming on the efficiency of phosphates 1 
Soil No. 
Phosphates applied immediately before 
planting. 
Phosphates applied 6 weeks before 
planting. 
Add 
phos¬ 
phate. 
Floats. 
Bone 
meal. 
Basic 
slag. 
Double 
super¬ 
phos¬ 
phate. 
Add 
phos¬ 
phate. 
Floats. 
Bone 
meal. 
Basic 
slag. 
Double 
super¬ 
phos¬ 
phate. 
*524 . 
hi 
20 
44 
84 
102 
91 
17 
48 
85 
82 
XS 78 . 
72 
5 
26 
64 
79 
76 
6 
20 
67 
84 
1257. 
75 
14 
61 
56 
59 
117 
21 
84 
106 
98 
1810.. 
119 
6 
81 
127 
121 
l6 
AX 
T T T 
Zl6 
1811. 
96 
33 
97 
86 
84 
95 
31 
40 
70 
A X 4 
78 
98 
1716. 
128 
50 
97 
114 
128 
143 
186 
138 
126 
133 
1529 . 
192 
1 
44 
98 
250 
151 
6 
44 
76 
154 
1796 . 
6i 
6 
23 
59 
55 
67 
8 
29 
8 l 
76 
213. 
90 
0 
15 
53 
Average*. 
107 
17 
59 
86 
108 
108 
36 
60 
91 
105 
1 The efficiency of each phosphate in the unlimed soil, applied immediately before, or 6 weeks before 
planting taken as ioo; the efficiency of the phosphates in the limed soil expressed comparatively. 
* Soil No. 213 not included. 
Evidently the effect of lime on the efficiency of the phosphate depends 
largely upon the character of the soil. In three soils liming had little 
influence on the efficiency of acid phosphate which was applied im¬ 
mediately before planting was done; in three soils, it depressed the effi¬ 
ciency; and in three soils it increased the efficiency of acid phosphate. 
The action of lime was equally variable in the different soils in the case 
of basic slag and double superphosphate. Although the efficiencies of 
floats and bone meal were depressed by lime in all soils except No. 1716, 
the extent of the depression varied greatly according to the character of 
the soil. 
