Soil Test Experiment in 1918. 53 



Grouped by the plots at the points of the triangle and by 

 the center plots (See diagram page 36) the average yields 

 are: 



Hundredweight per acre 



1917 



1918 



1917-18 



157 



121 



139 



152 



135 



143 



111 



122 



117 



115 



105 



110 



117 



115 



116 



158 



148 



153 



154 



144 



149 



153 



145 



149 



109 



96 



103 



Three ammonia plots, N3 in diagram 

 Five ammonia plots, N5 in diagram 

 Three available phosphoric acid plots, P3 in 



diagram 103 112 108 



Five available phosphoric acid plots, P5 in 



diagram 

 Three potash plots, K3 in diagram 

 Five potash plots, K5 in diagram 

 Three center plots, Comp3 in diagram 

 Six center plots, Comp6 in diagram 

 Three lower center plots, Am4 

 Seven check plots 



There are uneven yields but the limiting effect of nitrogen 

 is again shown in 1918. Its preponderance is shown by ar- 

 ranging the results in the order of the ammonia in the fertili- 

 zer mixtures. 



Hundredweight per acre 



No ammonia 5 plots* 

 Four per cent ammonia 5 plots 

 Eight per cent ammonia 4 plots 

 Twelve per cent ammonia 3 plots 

 Sixteen per cent ammonia 2 plots 

 Twenty per cent ammonia 1 plot 

 *Omitting plot 39 for 1917. 



Average yield from plots carrying ammonia and potash and no phos- 

 phoric acid in the fertiliser mixtures. 



. Hundredweight of potatoes 

 1917 1918 Average 



Average yield 4 plots 150 149 150 



Average yield from plots carrying ammonia and phosphoric acid and 

 no potash in the fertilizer mixtures. 



Hundredweight of potatoes 

 1917 1918 Average 



Average yield 4 plots 146 141 144 



The above tabulations show that omitting phosphoric acid 

 from the fertilizer had no effect upon the yield, while omitting. 



[917 



1918 



1917-18 



101 



101 



101 



147 



139 



144 



150 



151 



151 



152 



150 



151 



160 



139 



147 



151 



94 



123 



