SOD CULTURE VERSUS TILLAGE 129 



A summary of the remaining plots is found in the following 

 five points : 



1. The main root systems of apple trees under the different 

 methods of culture were found to be at a surprisingly uniform 

 depth, the greater portion of the roots, both large and minute, 

 being removed with the upper six inches of soil. 



2. The fibrous or feeding-root system of a tree under annual 

 plowing and clean culture with cover crops practically renews itself 

 annually, pushing up thousands of succulent, fibrous rootlets to 

 the very surface of the soil, where they actually meet with the steel 

 hoes or spikes of the cultivator or harrow, especially in seasons 

 when moisture is abundant. Apparently but a small percentage of 

 these rootlets penetrate the lower, more compact, colder soil, but 

 they come to the surface soil in countless thousands of threadlike 

 extensions to feed where warmth and air and moisture combine to 

 provide the necessary conditions for root pasturage. As a matter 

 of fact, these feeding rootlets are cleanly pruned away by the 

 plowshare each succeeding year and without apparent injury to 

 the trees or crops ; but they have succeeded in performing their 

 function, and their places are occupied the succeeding season by 

 a new generation. 



3. The presence of a network or mass of fibrous rootlets upon 

 the surface of the soil beneath a heavy mulch and in the heavier 

 portions of the mulch itself is no indication whatever of the lack 

 or absence of feeding rootlets in the upper soil ; and the partial or 

 even total destruction of these surface feeders, which occurs during 

 the hotter, drier months of summer and during the severe cold of 

 winter, does not cause the trees to suffer in the least degree, as 

 there was invariably found to be a wonderfully dense network of 

 rootlets occupying not only the upper two inches of soil, but also 

 the succeeding four inches of soil below that. 



4. Inasmuch as the surface rootlets in or beneath a heavy mulch 

 do not increase disproportionately to those beneath the surface 

 soil, it becomes evident that the removal of the mulch, or even a 

 change from heavy mulching to the clean-culture and cover-crop 

 plan, would not be so disastrous as has been generally supposed. 



5. Under the sod-mulch system of culture the trees have 

 uniformly made a heavier, more vigorous growth than under any 



