THE ROTHAMSTED EXPERIMENTS 



417 



spectively. The data are given in pounds per acre removed in 

 the actual crops grown, on the plots receiving both minerals and 

 nitrogen in case of the Agdell field. 



TABLE 76. AVERAGE COMPOSITION OF CROPS GROWN ON AGDELL FIELD 

 Pounds per Acre actually removed in the Crops Harvested 



The results for wheat are the average of the eight crops grown 

 from 1850 to 1879; for turnips, the average is for three crops 

 (1864, 1872, and 1876); for beans, six crops (1854 to 1870 and 

 1878); and the clover data are averages of 1850 and 1874 for the 

 first and second crops. 



In Table 77 the data represent, as a rule, in pounds removed per 

 acre per annum, the averages for the 18 years, 1856 to 1873 (first 

 crops only). 



This mass of data concerning actual results with mixed grasses 

 is especially valuable for the use of the analytical mind. A cur- 

 sory examination will show that, within the groups, the total 

 yield of organic matter correlates better with the nitrogen and 

 phosphorus removed than with most other constituents, while 

 the amount of potassium removed seems to be controlled by the 



