47 



lu its average effect upon production of stover it stands first in Wor- 

 cester and it has produced a comparatively large effect in Shelburne 

 and Freetown. The average eff'ect per acre for this element is as 

 follows: hard corn from .2 to 6.2 bushels increase, stover from 165 

 pounds decrease to 682 pounds increase. 



Comparative Effect of Potash, Nitrogen and Phosphoric Acid upon 

 Production of Grain and Stover. \s bearing upon the relative effect 

 upon grain and stover production respectively of these ingredients of 

 the fertilizers used, our figures afford some interesting data. We 

 find that the grand average increase in hard corn and stover per acre 

 taking all our experiments into account is as follows : 

 For potaBh, hard corn, 6.51 bushels; stover, 643.3 pounds. 



For phosphoric acid, " 3.56 " " 211 " 



For nitrogen, " 3.72 " " 287.6 " 



Potash, then, gave an average increase over nitrogen as follows: 

 Hard corn, 1.73 times; stover, 2.24 times. Over phosphoric acid, 

 the average increase was respectively : hard corn, 1.83 times ; stover, 

 3.05 times. It thus becomes evident that potash produces relatively 

 more effect upon the yield of stover than upon that of grain, and 

 that it greatly exceeds either nitrogen or phosphoric acid in this 

 respect. Next to potash in its effect upon stover ranks nitrogen. 



CONCLUSIONS. 



1. The results of our experiments bring out in a striking manner 

 the fact that soils vary widely in their requirements. They therefore 

 confirm t!ie position taken in my circular letter that results obtained 

 in one k^cality, may be inapplicable in another ; and appear to estab- 

 lish the wisdom of the policy of local soil tests. 



2. It is evident that only when the farmer knows what his soil 

 requires can he produce the best economical results. It is folly to 

 continue the indiscriminate and blind use of fertilizers. 



3. The best method of ascertaining what is needed in any given 

 case to produce a particular crop is to put the question to the soil 

 itself; and this method, though requiring care at all points, and 

 caution in forming conclusions, is not in reality difficult. Such exper- 

 iments should abundantly repay the investigator in the practical 

 money value of the results. 



