100 



BULLETIN 699, U. S. DEPARTMENT OF AGRICULTUEE. 



RHODE ISLAND. 



The first field work of the Rhode Island station with raw rock 

 phosphate was reported by Flagg and Towar ^ in 1893, and consisted 

 of an experiment conducted for one year only. 



In 1912, Wheeler 2 reported results of a three-year experiment 

 with various phosphates. The short duration of these experiments 

 and the absence of check plots make a repetition of the details 

 unjustifiable. 



An experiment to test the relative value of various phosphates on 

 limed and unlimed land was begun by the Ehode Inland station in 

 1894.^ Hartwell * published a summary of the results of 20 years. 



It is said that the field selected for this experiment was of uniform 

 character, and had not been treated with fertilizer for a number of 

 years, producing only a small crop of hay previously to the plotting 

 of the land. The soil is Miami silt loam, composed of glacial drift of 

 granitic origin. In 1893 the field was divided into 18 plats (the num- 

 ber being increased to 20 the following year), of two-fifteenths 

 acre each, and in order to obtain an index to their natural fertility 

 Indian corn was grown on the entire number without the application 

 of any fertilizer whatever. The yields per plot obtained in this pre- 

 liminary experiment are given in part in Table LX. 



Tabue LX. — 'Fertility of plots as measured by the yield of Indian corn in 1893 

 previous to fertilizer treatment. 



Plot number. 



Yield per 



plot 

 (weight of 

 ear corn). 



Relative 



fertility 



(plot 

 67=100). 



Plot number. 



Yield per 



plot 

 (weight of 

 ear corn). 



Relative 

 fertility 



(plot 

 68=100). 



51 



Pounds. 

 159 

 124 

 140 

 142 

 127 

 79 

 111 

 114 

 130 



Per cent. 



122 

 95 



108 



109 

 98 

 61 

 85 

 88 



100 



52 



Pounds. 

 132 

 103 

 95 

 73 

 86 

 90 

 98 

 146 

 123 



Per cent. 

 107 



53 



54 



84 





56 



77 



57 



58 



59 



59 



60 



70 



61. 



62 



73 



63 



64 



80 



65 



66 



119 



67 



68 



100 









An inspection of Table LX will show that the yields of the odd 

 numbered plots (which were subsequently limed) were in nearly every 

 instance greater than the even numbered plots (which received no 

 subsequent applications of lime). It will also be seen that plots 61 

 and 62 which afterwards received applications of " floats " gave 

 smaller yields of corn than any of the other plots with the exception 

 of plots 58 and 60. 



While the yields obtained in only one year can not be taken as 

 proof of the relative natural fertility of the various plots, the indi- 

 cations are that plots 61 and 62 were poorer than most of the others 

 in the field including the check or no phosphate plots. 



iR. I. Agr. Expt. Sta., 5th Ann. Rept., pp. 159-160 (1893). 

 »R. I. Agr. Expt. Sta., Bui. No. 148, pp. 21-29 (1912). 

 «R. I. Agr. Expt. Sta.. 7th Ann. Rept, p. 122 (1894). 

 «R. I. Agr. Expt. Sta., Bui. No. 163 (1915). 



