

EFFECT OF NITROGENOUS FERTILIZERS. 161 
It will be noticed that there are more analyses of crops from 
the plots with nitrate of soda than of crops from the plots with 
sulphate of ammonia. This is due to the fact that the ex- 
periments upon the former plots extended through three years, 
while those upon the latter extended through only two. 
Table 26 gives the total yields of water-free substance and 
the computed yields of food constituents. The yields of water- 
free substance per acre were determined from the weights of 
the crop when harvested and the percentage of water found in 
the sample when dried. The yields of protein, fat, etc., were 
calculated by multiplying the weight of the yield of water-free 
substance per acre, given in this table, by the percentages of 
protein, fat, etc., found by analysis of the samples from the cor- 
responding plots as given in Table 25. 
In all the experiments the results from plots with like kinds 
and quantities of fertilizers are averaged, as shown by figures 
in bold face type. These averages are the values which are 
given in the summary Tables 9 and Io, on pages 130 and 132 
in the discussion of results. 
