Food from the Soil 145 



droppings, and returned, too, with increased fertilizing 

 powers, that the land is actually benefited, and needs 

 no other manure; whereas hay-meadows cannot go 

 on bearing crops year after year without being manured 

 or top-dressed, to make up for their yearly loss. 



It is a different matter, of course, where the crops 

 grown by nature are concerned ; for these, being neither 

 machine-mown nor scythe-mown, so far from rendering 

 the soil poorer, really do much to enrich it. 



Herds of wild cattle may eat off grass and herbage, 

 as they did for ages before man came and took posses- 

 sion of their grazing grounds, but they manured the 

 soil in return. And the same is true, in its degree, 

 of squirrels, monkeys, birds, bats — in fact, of all the 

 grain, fruit, and vegetable eaters. 



The same is also true, though in a different way, of 

 the plants themselves. If they are left alone, they 

 return to the soil all that they have taken from it, and 

 more besides. For they give to it, also, that food 

 which they draw from the air, of which we have yet to 

 speak. 



The roots of a tree are constantly bringing up sup- 

 plies from the deep subsoil, which, when the leaves fall, 

 are added to the surface-soil ; and the ancient forests 

 of North America, after flourishing for ages, and pro- 

 ducing enormous quantities of timber, left the soil, 

 not impoverished, but so rich that it was hardly 

 exhausted by a whole century of wasteful farming. 



The ' yellow earth ' of China, a deposit of very great 

 extent, is believed to consist very largely of the ashes 

 of plants, accumulated during more generations than 

 one can attempt to realize, for in some parts it is more 

 than 1,500 feet thick. 



zo 



