68 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTURE. 
Tt will be seen that while dissolved bone black led for the first 
two years, during the remainder of the experiment several of the 
relatively insoluble phosphates forged ahead, phosphatic slag being 
first, South Carolina floats second, and Moria guano third. Florida — 
Cound rock phosphate, however, gave relatively poor yields when 
compared with the plot treated with South Carolina floats. t 
In Table XXXVIII the average relative rank of the. various 
plots from the beginning of the experiment, until it was discon- 
tinued in 1902, are expressed on a percentage basis. 
TABLE XXXVIII.—Average relative rank of the plots treated with various 
phosphates* (equal money values) during the 12 years? of the experiment. 
Treatment. Per cent. 
Basic (phosphatic) slaget sic atee coe eee ee eee eae eee 
Ground South Carolina rock 
Dissolvedsbone black. 33 a-22 Bes. ae eee eee cee tere 
Mona San. c25o-6 soa enise eck see eassseeeeeelae acer ne 
j= Blorida phosphate nockss~-=--ee nate eae eee eee 
Nos phosphate: (6;yeats) tanseee ete eee eee eee 
1No phosphates applied after the third year. 
2 The crop of Swedish turnips-grown in 1897 is not included, since it 
was damaged by disease. 
While the basic slag and ground South Carolina phosphate plots 
led all the rest in this experiment, the dissolved bone-black plot was 
not far behind. 
Brooks? considers that the phosphates in this experiment were ap- _ 
plied in a very irrational manner and in a way favorable to the rela- 
tively insoluble varieties, but even under these conditions he con- 
cludes that the data do not prove that the less soluble were more 
effective than the readily soluble phosphates since the yields from the 
Mona guano and Florida phosphate plots (particularly the latter) 
were materially less than that of the acid phosphate plot. 
While the writers feel that the data obtained are hardly sufficiently 
consistent to warrant a definite conclusion regarding the relative 
merits of the various phosphate carriers, nevertheless they are of the 
opinion that the method of applying phosphates in this experiment 
was considerably more logical from an economic standpoint than 
that employed in the subsequent experiment of the Massachusetts 
station upon which Brooks lays much greater stress. 
In 1897 a second experiment? was undertaken by the Massachu- 
setts station to test the fertilizer value of various phosphates when 
they were applied in such amounts as to furnish equal quantities of 
phosphoric acid to the soil. 
1Mass. Agr. Expt. Sta., Bul. No. 163, pp. 147-148 (1915). 
2 Hatch Agr. Expt. Sta., 10th Ann. Rept. (1898). 
