25 



Here the question arises as to how much of this effect was due to 

 nitrogen and how much to phosphate. Any answer to this can be of 

 course only an approximation of the truth and hence the values ob- 

 tained and shown in the following table are not to be taken too lit- 

 erally. They are the nearest approach to the correct values, how- 

 ever, that we are able to obtain at this time and they were derived 

 in the manner indicated in the footnote to the table. 



TABLE IV. 



Influence of Fertilizer Elements on Yield, Color and Growth.^ 



Estimated Per Cent, of Benefit. 



Expts. 215, 216, 220. 



Yield. 



Color. 



Growth- 



1908-9. 



1909 



1908-9. 



1907-9. 



Nitrogen, In Combination, 



1 49.2% 



15.55% 



—19.35% 



12.1% 





1 8i.i 



104.2 



— 21 .1 



19.4 



Ave. Influence of Nitrogen, . . 



1 65.2 



59.9 



— 20.23 



15.8- 



Phosphate, In Combination, . . . 



1 28.9 



35.65 



— 3.13 



— 3-2 



Phosphate, Alone, 



1 6.2 



52.2 



3.3 



— 1-7 





33.6 



20.85 



4.8s 



7.0 





1 138.3 



178.5 



—9.1 



21 .6 





— 21 .7 



— 21 . 



.9 



g.6 



Expts. 336, 338, 339. 



Yield. 



Color. 









1909 (2nd year). 



1909. 



Nitrogen, In Combination, .... 



236.5% 



—11.9% 



Phosphate , In Combination, . . . 



76.2 



— 2.7 





— 22.9 



— -3 





109.7 



— 2.4 





19.9 



— 2.8 



These results, being derived from those in tables II and III, 

 are naturally not materially different, as a whole, but the values of 

 the individual elements stand out more sharply. 



Nitrogen and stable manure show striking beneficial effects on 

 both yield and growth and characteristically harmful effects on 

 color. The effect of the manure is greatest in the third year of the 

 first three experiments, while that of the nitrogen is astonishingly 

 great in the second year of the three later experiments. 



Phosphates are showing considerable value on yield, especially 

 when used in combination with other materials. Their effect on 



^The results here given are calculated or taken from Tables II and III. 

 For example, the value of nitrogen in combination was obtained bv following 

 NP+NK— PK 



the formula . In other words, the per cents of benefit ob- 



2 



tained in plots two and three were added, from this sum was deducted the 

 per cent of benefit in plot 5, and the remainder, divided by 2, is considered 

 to be the value of nitrogen in the combination. The other values in com- 

 bination were obtained similarly. 

 ^Per cent of increase in trunk girth. 



