52 



MASS. EXPERIMENT STATION BULLETIN 209. 



These figures indicate a slight response in circumference increase ap- 

 parently due to the fertilizers, but not enough to be of much significance. 



Yield Records. 

 The yield records of this orchard have been kept by plots only. Inas- 

 much as the plots are of different sizes and include different numbers of 

 trees, it seems best to divide the total plot yields by the number of bearing 

 trees, thus obtaining the average yield per tree. The average total yield 

 per tree is shown in Table 4. 



The lowest yield is from the unfertilized plot, 3, and the highest yield 

 is from the muriate and magnesium plot, 6. Plots 4 to 8 show rather 

 uniform yields, varying from 194 to 241 pounds per tree, and it is probably 

 unsafe to attribute the differences that do show to the differential fertilizer 

 treatment. The yield from the ashes plot (189 pounds) is only a little 

 below that of these plots, and may or may not indicate that this fertihzer 

 treatment was less effective in producing apples than the treatments 

 given to plots 4 to 8. The yield on the manure plot is low and may indi- 

 cate an inferiority of manure as fertilizer on this soU, yet it should be 

 noted that these trees were at first the smallest in the orchard, and at the 

 end of the experimental period were exceeded in trunk circumference by 

 all except those on the unfertilized plot. Plots 4 and 5 received practically 

 the same fertilizer treatments as plots 4 and 5 in the station orchard, the 

 results from which this experiment was planned to explain. The difference 

 in yield is here only 7 pounds per tree, a degree of similarity rarely secured 

 from plots receiving identical fertihzer treatments. 



Fig. 11 shows the average yield per tree by two-year periods, — 1911 

 and 1912, 1914 and 1915, and 1916 and 1917, — there being no crop in 

 1913. The most significant fact brought out here is that the unfertilized 

 plot shows practically the same yield for each period, while the fertihzed 

 plots all show substantial gains for the second two periods over the first. 

 The slag-sulfate plot, 8, shows a large gain, and the manure plot, 1, makes 



