Soil Test Experiment in 1918. 49 



ammonia (nitrogen) was the limiting factor and their introduc- 

 tion would mask the effects of phosphoric acid and potash. 



Five no phosphoric acid plots 26 



Four 4 per cent phosphoric acid plots 24 



Three 8 per cent phosphoric acid plots 21 



Two 12 per cent phosphoric acid plots 19 



One 16 per cent phosphoric acid plot 23 



Five no potash plots 24 



Four 4 per cent potash plots 23 



Three 8 per cent potash plots 25 



Two 12 per cent potash plots 20 



One 16 per cent potash plot 21 



CLOVER. SERIES B, I918. 



The clover plots (Series C) in 1918 were not harvested 

 but were plowed under in the fall of 191 7 in preparation for 

 the 1918 plotato plots. Series B 1918 were seeded to clover 

 with oats in the spring of 1917. A mixture of equal parts red 

 clover and alsike clover were used. The crop of 1918 was 

 composed of about 9 parts alsike to 1 part red clover. 



As indicated by the varying yields obtained on the check 

 plots, factors such as stand, residual plant food, possible lack 

 of lime etc., on some plots evidently had far more to do with 

 the yield of clover than the fertilizers had. During the whole of 

 the growing season the plots were apparently very uneven in 

 stand, thrift and general appearance. On the check plots as 

 well as the. plots that are fertilized fairly alike the yields have 

 very little relation to the fertilizer used or the location of the 

 plots in the field. The lowest yield on a chick plot was less 

 than half that on the almost adjoining check plot. Clover is 

 supposed to respond to mineral fertilizers rather than to am- 

 monia, but the highest yield was from the plot carrying only 

 ammonia in the added fertilizer and the lowest yield on any 

 fertilizer plot was that to which potash was applied. 



The plots arranged in their relation to the fertilizer ap- 

 plied are shown in the following triangular diagram. 



