55 



plant-food — nitrogen, phosphoric acid and potash — four comparisons 

 are made. For example in the case of nitrogen ; 



1. The crop where nitrogen alone is applied is compared with the 

 average of the two nearest nothings. 



2. The increase {or decrease) when nitrogen and phosphoric acid 

 ax'e used is compared with the increase [or decrease) where phosphoric 

 acid only is used. 



3. The increase {or decrease) wliere nitrogen and potash are used 

 is compared with the increase {or decrease) where potash only is used. 



4. The increase {or decrease) where nitrogen, phosphoric acid 

 and potash are used is compared with the increase {or decrease) 

 where the two latter only are used. 



5. The results of the four comparisons are added, the sum 

 divided by four, and the result is considered the average increase {or 

 decrease) due to nitrogen. 



Upon this average the profit or loss from the use of nitrogen is 

 calculatt'd, no allowance being made for unexhausted residue. 



Similar comparisons and calculations are made for phosphoric acid 

 and potash. The results for all these ingredients are shown in 

 tabular form under each experiment. 



For convenience of comparison witli each other and with the 

 results just mentioned, the net results of the use of "complete" 

 fertilizer, barn-yard manure, plaster and lime are shown in another 

 table, although this plan involves the repetition of some of the figures 

 given in the general tabular view of the entire experiment. Below 

 this table will be found a calculation as to the financial result of the 

 use of each. In this calculation no allow^ance is made for unexhausted 

 residue of either manure or fertilizer. This omission undoubtedly 

 makes the showing for manure more unfavorable than it should be. 

 If we make the usual allowance of one-half, the manure will come 

 much nearer paying for itself, and for labor of application which, it 

 should be remembered, has not been chai-ged. The expression 

 "complete" fertilizer is used in the ordinary sense to designate 

 a mixture which supplies nitrogen, phosphoric acid and potash. 



