SOIL MANAGEMENT FERTILIZATION OF ORCHARDS. 37 



The check plot (plot 3) had fallen below SO per cent at the commence- 

 ment of our records, and continued to fall off rapidly up to 1911. From 

 1911 to 1915 it not only kept up with plot 1, but actually gained quite 

 rapidly. Since 1915 it has kept even with plot 1 until the season of 1920, 

 when plot 1 made remarkably strong growth, causing a relative falling 

 off of plot 3 and of the other three plots as well. 



The relative gain of plot 3 is bej^ond doubt due to cultivation of strips 

 between the tree rows begun in the fall of 1910. As shown in Fig. 1, 

 cultivation does not seem to have increased the growth on plot 1, but its 

 effect is seen in all the other plots, though most strikingly in plot 3. 



Fig. 1. — Increase in trunk circumferences. The perpendicular line marks the transition 

 from sod mulch to strip cultivation. Plot numbers are shown at the right. See page 

 35 for treatments given. 



Iso fertilizers of any kind have been applied since 1916, yet the growth 

 on plot 1 has been well maintained as shown in Fig. 1. The other plots 

 show a decrease in rate of growth since 1915, as shown in Fig. 2. It 

 seems doubtful if this can be ascribed wholly to the cessation of fertilizer 

 applications, because the decrease appears first in 1916, when fertilizers 

 were applied, and it is seen in plot 3 which has never had any fertilizer 

 applications. It seems more reasonable to suppose that the relative gain 



