46 



MASS. EXPERIMENT STATION BULLETIN 209. 



as 100. These figures show clearh^ how plot 1 has often been exceeded 

 by the other plots in the off years and scarcely at all in the on years. 

 The increased production of the ashes and unfertilized plots since strip 

 cultivation was begun is shown. The relative decrease of the ashes and 

 unfertilized plots under sod mulch is shown, and also their gain on the 

 manure plot when strip cultivation was begun. The unfertilized plot still 

 continues a relative increase, while the ashes plot shows a falling away 

 in the last few years. Fig. 8 shows clearly the parallel courses of the 

 muriate and sulfate plots, with a relatively wider difference under sod 

 mulch, and a gradual convergence since strip cultivation has been prac- 

 ticed. 



Fig. 8. — Relative yields of plots 1, 4 and 5. Yields on plot 1 taken as 100 per cent. 



Correlation between Growth and Yields. 

 It i.-^ interesting to compare these graphs with Fig. 2 showing similar 

 measures of growth as indicated by trunk circumference. Several investi- 

 gators have shown a close correlation between growth and fruit production. 

 Within limits the two go together, — the more growth the greater fruit 

 production. This conclusion is sup'ported by a comparison of Fig. 2 with 

 Figs. 7 and 8. Especially do the lines representing growth and production 



