Journal of Agricultural Research 
Vol. XXV, No. 4 
186 
Very little difference was observed in the efficiency of bone meal re¬ 
gardless of whether the lime was applied six weeks or one day before 
the phosphates were used. The quantity of lime applied, however, had 
a most pronounced effect. The efficiency of bone meal was almost 
negligible in the presence of a considerable excess of lime, such as was 
afforded by the 42.12 gm. per pot. 
The data given in Table VII show that applications of lime equivalent 
to the “lime requirement” of the soil may increase, decrease, or be 
without appreciable effect on, the efficiencies of acid phosphate, basic 
slag, and double superphosphate, according to the character of the soil. 
Such quantities of lime may be expected to reduce the efficiencies of 
floats and bone meal much more generally and to a greater degree. 
Table VIII shows that the quantity of lime applied markedly influ¬ 
ences the efficiencies of the phosphates. It would therefore be expected 
that even on soils such as No. 1529 and 1716 where a certain quantity 
of lime noticeably increased the efficiencies of acid phosphate, basic 
slag, and double superphosphate, a larger application of lime would have 
decreased the efficiencies of these materials. 
This conclusion is borne out by the results that are being obtained 
at the Rhode Island Experiment Station (<£). A certain quantity of 
lime on the Kingston soil markedly augments the efficiencies of the 
phosphates for some crops. Liming beyond a certain point has the 
reverse effect, however. At least, liming beyond a certain point brings 
about such a condition in the soil that smaller increases are produced 
by a given quantity of phosphoric acid from some phosphates. 
Although pot and field experiments show that liming affects the 
efficiency of a phosphate in the sense that a given quantity of the phos¬ 
phate produces a larger or smaller crop increase on limed soil than on 
unlimed, results obtained with only one or two kinds of phosphates do 
not necessarily show that liming affects the quantity of phosphoric acid 
which is in an assimilable condition. It may be that in certain cases 
liming is without influence on the assimilability of the phosphoric acid 
applied and merely corrects or exaggerates a soil condition which is so 
affecting the growth of the plant that it responds less markedly to an 
increase in the quantity of assimilable phosphoric acid. The depressing 
effect of lime observed in the experiments reported in this paper, how¬ 
ever, are believed to have been due to the effect of the lime on the quan¬ 
tity of phosphoric acid available to the plant; otherwise, it would hardly 
be understandable why floats should have had such a low and constant 
efficiency in the limed soils (Table V) and why the efficiencies of some 
phosphates were depressed less than others. 
EFFICIENCIES OF THE PHOSPHATES AS AFFECTED BY REMAINING 
IN THE SOIL 
The extent to which the efficiencies of the various phosphates were 
affected by remaining six weeks in the unplanted soils is shown in Table 
IX. In this table the efficiency of each phosphate applied immediately 
before planting, to either the limed or the unlimed soil, is expressed as 
100, and the efficiency of the material applied six weeks before planting 
is expressed as relative to 100. 
