64 



BULLETIN 699, U. S. DEPARTMENT OP AGEICULTUKE. 



made to determine the relative natural fertility of the various 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. 



Plot number. 



Wheat, 1899. 



Hay. 



Total of 3 

 crops. 



Average 

 yearly 

 yield. 



Grain. 



Straw. 



1900 



1901 



1 



Pounds. 

 1,535 

 1,415 

 1,835 

 2,130 

 2,120 

 2,100 

 2,190 

 2,165 



Pounds. 

 2,800 

 2,630 

 3,565 

 4,070 

 3, 980 

 4,300 

 4,310 

 4,100 



Pounds. 

 4,050 

 3,500 

 3,600 

 4,500 

 4,550 

 3,450 

 4,350 

 2,500 



Pounds. 

 4,010 

 3,150 

 3,900 

 3, 750 

 4,050 

 3,750 

 4,100 

 4,400 



Pounds. 

 12,395 

 10,695 

 12,900 

 14,450 

 14.700 

 13,600 

 14,950 

 13, 165 



Pounds. 

 4,132 



2 



3,565 



3 



4,300 



4 .... 



4,817 



5 



4,900 



6 



4.533 



7 



4,983 

 4,388 



8 





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 XXXV. 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 liberal application 

 of lime. 



