42 



MASS. EXPERIMENT STATION BULLETIN 209. 



the smaller size of the trees. The manure plot has been the best producer 

 in most years, and its superiority seems to have increased in the last three 

 on-year crops. The ashes plot has approached the manure plot more 

 closely since 1911 than before. The unfertilized plot has been, up to 

 1920, far in the rear of all the fertilized plots, though showing material 

 gains in on-year jaelds since 1911, which brought it slightly above the 

 muriate plot in 1919. 



Fig. 4. — Total yields by plots in hundreds of pounds. The odd numbered years are the 

 bearing or "on" years. Figures at left are hundreds of pounds. 



It is apparent that the effect of the manurial treatment on j'ield has 

 been slight in the oft" 3'ears, but in the on years it seems reasonable to con- 

 clude that there have been differences in j^ield due to the different manurial 

 treatments. These differences in the on years follow closely the differences 

 in growth of the trees. It is probable that the fertilized plots have ex- 

 ceeded in yields the unfertilized plot mostly because the trees were larger. 

 The fertilized plots have received greater or less supply of nitrogen. 



