EXPERIMENTAL WORK WITH RAW ROCK PHOSPHATE. 29 
field was conducted for the purpose of comparing the effects of 
various phosphates on Indian corn. 
The plots were treated with liberal applications of potash and 
nitrogen in readily available form and the various phosphates were 
applied in quantities representing (at that time) equal money values. 
During the second and third years of the experiment no further 
additions of phosphates were made, in order that their residual 
effects might be studied, but the applications of potash and nitrogen 
carriers were made each year. During the first year of the experi- 
ment the plot treated with acid phosphate showed to considerably 
greater advantage than those receiving raw ground South Carolina 
rock (560 pounds per acre), but in the second and third years (with 
no further additions of phosphates) the production of the acid- 
phosphate plot fell off, while that of the raw-rock plot increased to 
such an extent that it surpassed the yield obtained from the acid- 
phosphate plot during the first year of its application. 
The results of 17 other short-time experiments, 15 of which were 
continued for only one year, were reported by the Connecticut sta- 
tion? between the years 1888 and 1895, but while most of these 
showed indications of beneficial results from the use of raw rock 
phosphate, the data given are too meager to warrant serious con- 
sideration. 
While the results of the field work with raw rock phosphate so far 
presented by the Connecticut Experiment Station must be regarded 
as only indications at best, they are nevertheless favorable to the 
use of raw rock phosphate. 
DELAWARE. 
The only experiment with natural phosphates yet reported by the 
Delaware station was a pot test conducted by W. H. Bishop? in 1893 
in which a study was made of the effects of various phosphates (in 
combination with potash and nitrogen carriers) on the yields of 
soy beans planted in three different types of soil. 
Although the soluble phosphates led all the others, the short dura- 
tion of this experiment (one year), the ight applications of the rela- 
tively insoluble phosphates—applications which would add less than 
0.007 per cent of P,O, to a soil of medium texture—and the wide 
divergence in the yields of some of the check pots make these results 
hardly worthy of repetition. 
1Conn. Agr. Expt. Sta., 14th Ann. Rept., pp. 203-219 (1890); 19th Ann. Rept., pp. 
122-127 (1895). 
2Del. Agr. Expt. Sta., 6th Ann. Rept., pp. 198-202 (1893). 
