THE SOIL AND SOIL FORMATION 



73 



downward four to six feet, and in some cases much 

 deeper. In humid regions, however, the greater number 

 of fine root branches are found in the first foot or 18 

 inches of soil, in which are the best conditions for the 

 roots to secure food. The depth at which most plants 

 prefer to feed, if sufficient water is present, is the lower 

 half or two-thirds of the furrow-slice, and that part of 

 the subsoil immediately beneath. While the roots which 



go deepest into the 

 earth secure some 

 food, the chief function 

 of the deeper roots is 

 to bring up water 

 when the supply near 

 the surface is deficient. 

 These long, deeply 

 penetrating roots have 

 few branches near the 

 tip, while nearer the 

 surface of the soil the 

 root branches are very 

 numerous. The roots 

 spread out so as to 



Figure 18. At 6 are shown the stem roots of a 



. 



reach the p ]ant food m 



every nook and corner 



roots penetrate nearly 4 feet downward, while the r ^t,.^ 111- t-r->-i*r 



horizontal spread, including the branches, not I tn ^ lUrrOW- 



shown in 6, is over 6 feet. This drawing was , i 



made from a plant, nearly every stem root of which Uppermost layers 



was dug out by means of a small wooden trowel, . ., 



the length, depth and direction of the root being SUDSOll. 



accurately recorded on the drawing, _ . ,, 



In figure 18 is shown 



the root system of a corn plant ready to tassel. The 

 branch roots are not represented at 6. They are so 

 numerous that it is impossible to show all of them in 

 this diagram. The roots there shown are the mere frame- 

 work, or main roots, their branches and sub-branches 

 being very much more numerous. At "X" is shown one of 

 the roots arising from the stem, with its branches. Only 



