676 THE SURFACE CULTURE OF FOREST TREES. [Mar. 



but the tops were weakly and jaundiced-looking, and the crop of 

 tubers small and light. On digging them, however, the dung came 

 up fresh, and almost as pungent as when applied to the sets, the 

 water having set its seal on decomposition, and thus robbed the 

 crop of the food provided for it in the dung. The same thing is 

 constantly liappening in plantations. It is a common thing to say 

 of wet woods that tlie trees are starved from cold. It would, however, 

 be far nearer the trutli to say that they were starved from hunger. 

 The roots in wet woods are surrounded with food in all directions 

 but without a bit to eat, like thirsty mariners at sea, who have 

 " water, water everywhere, but not a drop to drink." 



But our second lock, though hardly so strong as the first, is also 

 very potent in depriving or robbing the roots of plants of their 

 legitimate supplies of food. This lock is formed of surface weeds, 

 and it is not only a niggardly lioldfast but an expert robber. A 

 screen of surface weeds shuts out the air to a very great extent. It 

 may, and in fact often does, become so dense as to prove almost 

 impervious to air. "When that results from a carpet of surface 

 weeds they lock up the fertility of soils almost as completely as 

 water. But with this wide difference, that the weeds feed on the 

 soil themselves, and so misappropriate, tliat is, steal the food 

 intended for the forest trees or other plants. By destroying the 

 weeds, and scarifying the surface more or less deeply and frequently, 

 we neutralize at once their miserly and peculating functions, and 

 set free and conserve the whole feeding force of the soil for our 

 forest trees. Surface culture does even more than this, for it 

 admits more heat and air to the soil, both of which are stimulating 

 forces to growth. But this may very properly be considered under 

 our third natural lock on the fertility of soils. This is solidity — 

 often also associated with sourness of surface. It is often the joint 

 product of water and weeds, and may also be found where neither 

 exists to any injurious extent. This state of surface arises from 

 lapse of time and lack of disturbance. It is aggravated by surface 

 iioodings, the growth of inferior vegetation, such as mosses, etc. 

 These and other causes tend to render the surface, and a proportion, 

 or even the whole, of the tilth, impervious to air, and this imper- 

 viousness locks up the feeding properties of soils, and render these 

 almost as powerless to foster growth as if they were not present within 

 easy reach of the roots, i'or atmospheric air is not only the liberator 

 of all the manurial forces of the soil, but is the only power that can 

 present them in such forms to the roots of plants as to enable the 

 latter to absorb or utilize them. More than that, some of the 

 constituents of the air may become amongst the most valuable 

 factors of plant food. The presence of air also quickens and enlarges 



