EXPERIMENTAL WORK WITH RAW ROCK PHOSPHATE. 29 



field wa3 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 light applications of the rela- 

 tively insoluble phosphates — applications which would add less than 

 0.007 per cent of PoOg 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. 



iConn. Agr. Expt. Sta., 14th Ann. Rept, pp. 203-219 (1890); 19th Ann. Rept., pp. 

 122-127 (1895). 



•Del. Agr. Expt. Sta., 6th Ann. Rept., pp. 198-202 (1893), 



