220 ASU OF THE GRASSES ANE . ..OVERS. 



VII. OF THE ASH OF THE GRASSES AND CLOVERS. 



The following table might have been much enlarged. I have 

 thought it .necessary, however, to introduce in this place only those 

 species of grass and clover which are in most extensive use. I have 

 also calculated the weights given below, for these plants in the state of 

 hay only, as the succulency of the grasses, — that is, the quantity of wa- 

 ter contained in the green crop, — varies so much that no correct esti- 

 mate could be made of the quantity of inorganic matter present in hay 

 or grass, from a knowledge of its weight in the green state ouly : 



52-86 74-78 91-32 95-53 69-57 



The above quantities are contained in a thousand pounds of the dry 

 hay of each plant. 



On comparing the numbers opposite to potash, lime, magnesia, alu- 

 mina, silica, and })hosphoric acid, we see very striking differences in 

 the quantities of these substances contained in equal weights of the 

 above different kinds of hay. These differences lead to very important 

 practical inferences in reference, — 



1°. To the kind of soil in which each will grow most luxuriantly. 



2°. To the artificial means by which the growth of each may be pro- 

 moted — in so far as this growth depends upon the supply of inorganic 

 food to the growing plant. 



3°. To the feeding properties of each, and to the kind of stock they 

 are severally most fitted to nourish. 



To these and other important practical deductions suggested by the 

 above tabulated analyses — as well as by those previously given — of the 

 inorganic matters contained in the several varieties of vegetable produc- 

 tions usually raised for food, we shall hereafter have frequent occasion 

 to revert. In the mean time, a preliminary inquiry demands our at- 

 tention, which we shall proceed to consider in the following section. 



§ 4. To what extent do the crops most vsually cultivated, exhaust the soil 

 of inorganic vegetable food ? 



A bare inspection of the tabular results exhibited in the preceding 

 section gives but a faint idea of the extent to which the inorganic ele- 

 mentary bodies are necessarily withdrawn from the soil in the ordinary 

 course of cropping. 



