66 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTURE. 
In order to see at a glance the apparent relative values of the 
various phosphates used in this experiment, the Maryland station 
compiled a table in which the yields given in Tables XXXIV and 
XX XV were reduced to a percentage basis, taking the yield of the 
Virginia phosphate plot as 100. The results are given in Table 
XXXVI. It will be noted that the average production of the differé 
ent plots after the application of the phosphates was less than before 
the treatments, but since the greatest decrease in yield was on the 
check plots, it is assumed that the phosphates had a beneficial effect. 
The figures in the column headed “ Relative increase ” represent 
the average relative increases of the various phosphate plots over the 
check plot. | 
TABLE XXXVI.—Relative yields and average inyuence of different forms of 
phosphoric acid, expressed in percentages. 
Rate of Rate of 
Phosphate treatment, 150 pounds P.O; per acre, in yield yield 
_the following forms: before ex- | during ex- 
periment. | periment. 
Relative 
Difference. ARES aG. 
eee 8) Oe ee 
Per cent. Per cent. Per cent. Per cent. 
Ground?south Carolina nocks-s == oe eeeeeeee eee eee 83 73 —10 1 
Dissolved: South Carolina LOCK {eens ae eee eee eee 72 72 0 20 
Dissolved South Carolina rock and lime..............-- 86 74 —12 8 
Check (moimphosph ate) es ass eee eee oeeiteece eer 97 vee SHG —20 0 
Ground: Rennesseeinocks 2 sas nee se tee ose necen eames 98 91 — 6 14 
G@rounGebilorid aproCk 2 eeeeern cheer eee ee oe 91 98 +7 27 
Groundaviairnsimiatrockss estes e eee eee eee eee 100 100 0 20 
Precipitated’ phosphatetess--- 2 ee eeaeeeeeee eee ne eee 88 93 +5 25 
Apparently the greatest effect was produced by the Florida soft 
phosphate and the precipitated phosphate treatments. The Virginia 
phosphate (which, it is.said, was largely a phosphate of aluminum) 
and the acid phosphate (without lime) came next with the same rela- 
tive increase. Contrary to popular belief the application of lime in ~ 
connection with acid phosphate did not in this experiment appear 
to be beneficial. 
The Maryland station results as a whole may be said to indicate 
that applications of the relatively insoluble phosphates in a finely 
divided or precipitated condition increase crop yields as effectively 
in some instances as the more soluble phosphates. 
MASSACHUSETTS. 
In 1890 the Massachusetts station undertook an experiment? to 
compare the relative fertilizer merits of acid phosphate (dissolved 
bone black) and some of the less soluble phosphates when the various 
forms were applied in quantities representing at that time equal 
money values. 
The field selected for this experiment was quite level and had been 
used as a meadow up to 1887. The soil was a fair sandy loam, but 
1Mass. Agr. Expt. Sta., 8th, 9th, 10th, and 11th Ann. Repts. Hatch Agr. Expt. Sta, 
14th Ann. Rept. (1902). 
Ce. Or 
