SOD CULTURE VERSUS TILLAGE 127 



The effects of the change from sod to tillage were almost in- 

 stantaneous. Tree and foliage were favorably affected before mid- 

 summer of the first year ; and the crop, while below the normal, 

 consisted of apples as large in size as any in the orchard, the 

 falling off in yield being due to poor setting. 



The change for the worse was quite as remarkable and as im- 

 mediate in the quarter of the orchard turned from tillage into sod ; 

 the average yield in this quarter was not half that of any one of 

 the other three quarters. 



The use of nitrate of soda in the sod plats greatly increased the 

 vigor of the trees and was a paying investment, yet for the five- 

 year period they bore out a trifle more than half as much as the 

 tilled trees. 



The very marked beneficial influence on the sodded trees of 

 ground adjacent under tillage teaches that not only should apples 

 not be grown in sod, but that for the best good of the trees there 

 should be no sod near them. 



Only in the amount of humus and nitrogen has the soil been 

 appreciably changed by the two treatments. The quantities of 

 humus and nitrogen in the plat tilled ten years are so much 

 greater that it is safe to assume that the tillage and cover-crop 

 treatment conserves these elements better than the sod-mulch 

 treatment. 



Grass militates against apples growing in sod in several ways 

 which act together ; for example : 



1 . Lowering the water supply. 



2. Decreasing some elements in the food supply. 



3. Reducing the amount of humus. 



4. Lowering the temperature of the soil. 



5 . Diminishing the supply of air. 



6. Affecting deleteriously the beneficial microflora. 



7. Forming a toxic compound that affects the trees. 

 General statements are as follows : 



Sod is less harmful in deep than in shallow soils. 



There is nothing in this experiment to show that apples ever 

 become adapted to grass. 



Sod may occasionally be used in making more fruitful an orchard 

 growing too luxuriantly. 



