100 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTURE. 
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? 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 Rhode Island station in 
1894.8 Hartwell* published a summary of the results of 20 years. 
It is said that the field selected for this expermnent 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 plots (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. 
TaBLleE LX.—Fertility of plots as measured by the yield of Indian corn in 1893 
previous to fertilizer treatment. 
Yield per | eetey ve \ ; oe per | Relative 
plot ertility lot fertilit 
Plot number. Greizht of | (plot Plot number. (weicht A (plat 
earcorn). | 67=100). || earcorn). | 68=100). 
Pounds. | Per cent. || | Pounds. Per cent. 
Bisse cna cae oe ee 159 |b -7 | ae ae re cee ee Se eI Se 132 107 
eee ey i ek ey 124 95 | BA fe te hoe cee ee i ae Napees 103 84 
eae oat ya oa 7 140 10894 [ 565 o ons ed 95 77 
ne ee Re et 142 109: | 585, ple 2 ee ee sae 73 59 
A) peso hay Reened * 12 127 98:/"G05. 23s ere aaa Ev 86 70 
eee SPS eas Sie tae 79 61516293: fai Ce ee 90 73 
eas ee ene ren eres 111 BO GE ee RS 98 80 
ee ee A a oe eae eas 114 |} 884) GBis 2s soe ee eee 146 119 
Ce ee Se ee Se 130 } 100! GSSee eee eee eee 123 100 
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 pte 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. 
1R. I. Agr. Expt. Sta., 5th Ann. Rept., pp. 159-160 (1893), 
2R. I. Agr. Expt. Sta., Bul. No. 148, pp. 21-29 (1912). 
SR. I. Agr. Expt. Sta.. 7th Ann. Rept., p. 122 (1894). 
4R. I. Agr. Expt. Sta., Bul. No. 163 (1915). 
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