46 



MASS. EXPERIMENT STATION BULLETIN 209. 



as 100. These figures show clearly 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 l^egun is shown. The relative decrease of the ashes and 

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

 manure plot Avhen strip cultivation Avas begun. The unfertilized plot still 

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

 in the last few 3'ears. 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. 



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



Correlation lictiveen (iroicVi and Yields. 

 It is 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 supported by a comparison of Fig. 2 with 

 Figs. 7 and 8. Especiallj' do the lines representing growth and production 



