176 



NATURAL HISTORY OF THE FARM 



that docs not 

 ground-cover. 



^'/. 





FlftL» 



Pig. 68. Diagram of a section of a pnrtly 

 wooded hill. /, oritjinal contour of the 

 hill slope; m, contour assumed after 

 tilling of the fiel Is; n, in-wash of soil 

 above; and o, out -wash of soil below. 



extensively destroy the roots nor remove 

 She fines tlie surface with the heav- 

 ing of winter frosts. She 

 stirs the deeper j^arts by 

 the borings of earthwonns, 

 by tlie excavating of bum )\vs 

 for the homes of mammals, 

 and by the overturn of the 

 roots of windfall trees. It 

 is here a little and there a 

 little, but in the long run it 

 is thoroughly done. 



We can see the contrast be- 

 tween nature's soil manage- 

 ment and our own on almost any slope where both fields and 

 woods occur. Wherever their boundaries run horizontally, such 

 contours as are indicated in figure 68 result from the rapid 

 sHpping away of the topsoil of our tilled fields. A ridge is 

 formed along the edge of the wood when the bare field lies 

 above it : the soil washed from the field is held by the ground 

 co\-er herbage at the edge of the woodland. When the field 

 lies below, a hollow is fomicd at the edge of the wood where 

 the tree roots cease to hold the soil together. To be sure, 

 gravity is always operating, and the soil of the woods is slowly 

 shifting to lower levels ; but it is only in the fields, where the 

 ground-cox'cr is removed and the root-hold periodically 

 broken, that the process goes on so rapidly that the soil seems 

 to melt and vanish before our eyes; it is only here and wdth 

 very bad management, that the organic products of one 

 season arc all taken from it before the next season comes 

 around. 



Let us go into the woods and look at the soil there. The 

 first thing we notice is that there is little soil to be seen— only 

 a few paths kept bare by passing feet. Here and there are 



