64 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTURE. 
made to determine the relative natural fertility of the varicus plots 
on the experimental field by uniform cultivation, and the growing of 
wheat and hay for three years preceding the application of the 
phosphates. 
The yields of the various plots during these three years are given 
in Table XXXIV. 
TABLE XXXIV.—Relative productive capacity of plots when receiving uniform 
treatment. 
Wheat, 1899. Hay. Aes 
Plot number. ee 3 “yearly 
Grain Straw 1900 1901 yield 
Pounds. Pounds. Pounds. Pounds. Pounds. Pounds. 
Dees o Bee ARS Bs Oe Owe 1, 535 2, 800 4,050 4,010 12, 395 4,132 
DAS 25 (ah, Re SE at Pi Pt aS <8 OE 1,415 2,630 3, 500 3,150 10, 695 3,565 
SY ane eee age a ae Wian Sey ete er 1, 835- 3, 565 3, 600 3, 900 12,900 4,300 
ee tas Meee Se Stet een 2,130 4,070 4, 500 3,750 14, 450 4,817 
Hae ae eae cic Mot Gees eieaeeusS 2,120 3, 980 4,550 4,050 14, 700 4,900 
Gee nese ae ee ae ee RS 2,100 4,300 3, 450 3, 750 13, 600 4,533 
eee eS EE ee 2,190 4,310 4,350 4, 100 14, 950 4, 983 
Se ee ee tiga Soe aca 2,165 4,100} - 2,500 4, 400 13, 165 4,388 
The figures given in Table XXXIV indicate strongly that this 
field was not of uniform fertility. They show how the relative yields 
of similarly treated plots may vary from year to year independent of 
fertilizer treatment, thus making it not only unwise but well nigh 
impossible to draw final conclusions from field work covering only a 
short period of time. 
The yields of the same plots after treatment with the various 
phosphates are given in Table XX XV. Besides introducing other 
varieties of phosphates into this experiment, the effect of liming on 
the soil was studied by employing two soluble phosphate plots, one - 
of which received in addition to acid phosphate a hberal application 
of lime. - 
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