EXPERIMENTAL WORK WITH RAW ROCK PHOSPHATE. 



31 



Table VIII.- 



-Yields of wheat obtained in pot experiment to test the relative 

 values of raw rock and steamed bone meal. 



Treatment. 



Wheat yields. 



Per pot. 



Per acre. 



Increase. 



Per acre. 



None 



Clover 



Bone meal 



Rock phosphate 



Clover, bone meal 



Clover, rock phosphate 



Manure 



Clover, manure 



Manure, bone meal 



Manure, rock phosphate 



Clover, manure, bone meal 



Clover, manure, rock phosphate 



Potash 



Clover, potash 



Potash, Done meal 



Potash, rock phosphate 



Clover, potash, bone meal 



Clover, potash, rock phosphate 



Manure, potash 



Clover, manure, potash 



Manure, potash, bone meal 



Manure, potash, rock phosphate 



Clover, manure, potash, bone meal 



Clover, manure, potash, rock phosphate 

 None 



Grams. 

 10.0 

 16.3 

 14.7 

 14.2 

 22.2 

 23.3 

 16.5 

 22.7 

 19.4 

 19.5 

 23.1 

 23.3 

 U.3 

 18.4 

 18.4 

 18.2 

 21.9 

 21.9 

 18.1 

 19.1 

 19.3 

 19.0 

 25.3 

 25.3 

 10.6 



Bushds. 

 27 

 43 

 39 

 38 

 59 

 62 

 44 

 60 

 52 

 52 

 62 

 62 

 30 

 49 

 49 

 49 

 58 

 58 

 48 

 51 

 51 

 51 

 67 

 67 

 28 



Bushels. 



The beneficial effects of phosphate in this particular experiment 

 are quite marked, even though the test was of comparatively short 

 duration. The results obtained seem to indicate that raw rock phos- 

 phate (an equal money value) may be substituted for bone meal, 

 particularly if the phosphate is applied with manure or turned under 

 with a leguminous crop. In practically every instance the raw-rock 

 pots equaled or surpassed the bone-meal pots with which they were 

 directly comparable. 



A number of papers by Hopkins ^ on the use of raw rock phosphate 

 as a fertilizer appeared in 1908 and 1909, but the field work of the 

 Illinois Station described in several of them is given more fully in 

 subsequent publications. One of these circulars ^ is a reply to a 

 pamphlet issued by the National Fertilizer Association advising 

 against the use of raw rock phosphates. This circular shows that 

 the quotations in this pamphlet from the Experiment Station bul- 

 letins are very incomplete and the conclusions drawn are unjustified. 



In 1910, 1911, and 1912 the Illinois station issued several publica- 

 tions ^ on raw rock phosphates, but only one is quoted here, since the 

 limited duration of the field work or the meager data given in the 

 others hardly justify repetition. 



» 111. Agr. Expt. Sta., Circular No. 116 ; Buls. Nos. 123 and 125 (1908) ; Circulars Nos. 

 127 and 130 (1909). 



* Circular No. 127 (1909). 



3 Lloyd and Brooks, Bui. No. 144 (1910); Hopkins, C. G., Circular No. 141 (1010); 

 Hopkins and Mann, Circular No. 149 (1911) j Lloyd, Bui. No. 155 (1912), 



