20 Maine Agricultural Experiment Station. 1918. 



zer formulas, the 5-8-7 formula, which makes a total of 20 per 

 cent of ammonia, available phosphoric acid and potash was 

 used as a starting point. Hence, in the diagram here shown the 

 extreme points of the triangle represent 20 per cent instead of 

 100 per cent as used by Schreiner. Although the fertilizer 

 mixtures are in reality based upon the percentages expressed 

 in terms of ammonia, phosphoric acid and potash the symbols 

 N, P, and K for the elements nitrogen, phosphorus and potas- 

 sium, which are the characteristic elements of these 3 constitu- 

 ents, are used in lettering. Wherever N is used in diagrams 

 or text it refers to ammonia in available form, P refers to avail- 

 able phosphoric acid and K to water soluble potash. 



The relation of the plots to each other is clearly seen by 

 following the lines on the triangle. The maximum phosphoric 

 acid (P) is at the left lower angle, the maximum potash (K) 

 at the right lower angle and the maximum ammonia (N) is 

 at the top of the triangle. From these points the different 

 ingredients diminish. On all of the horizontal lines the phos- 

 phoric acid diminishes from left to right and the potash from 

 right to left. On all of the lines inclined to the right the phos- 

 phoric acid decreases from bottom to top and the nitrogen 

 decreases from top to bottom. On all of the lines inclined to 

 the left the potash diminishes from the bottom to the top and 

 the ammonia diminishes from the top to the bottom. 



This plan calls for 21 plots. Obviously an indefinite num- 

 ber of plots could be introduced. To graduate on a scale of 

 tenths would give finer distinctions but would treble the plots 

 over a division into fifths as shown in the illustration and as 

 adopted in this experiment. In the scheme here adopted com- 

 binations of the 3 fertilizers in the amounts indicated at the 

 intersection of the lines were used. The actual percentage 

 composition of the fertilizers are given in Figure 3 and others 

 beyond. Obviously the plot at each apex and the 2 adjoining 

 carries the maximum amount of ammonia, phosphoric and 

 potash respectively, while the 6 central plots carry mixtures of 

 all 3 constituents. 



