HORTUS GRAM1NEUS WOBURNEiYSIS. 125 



Alumina - - 9.7816 



Oxide of iron - - 39.418 



Soluble saline matter 4.0876 



Carbonate of magnesia 0.0973 



The quantity of clay necessary to effect the above alteration in 

 an acre of the siliceous soil to the depth of six inches, and the 

 probable expense attending it, appear to be as follows : 



One acre of land, six inches deep, contains 37635840 cubic 

 inches. A cart-load, or one ton of clay, contains 21479.43 cubic 

 inches, which, applied in the proportion of one part to 19, as above, 

 shews that 60 cart-load, or 745.8J cubic feet of clay, are requisite 

 to effect that change in its nature. 



In ordinary cases, the expense of digging, filling, and spreading 

 the clay, is three-pence three-farthings per cart-load ; consequently 

 the expense per acre would be eighteen shillings and nine-pence, 

 exclusive of cartage. Now if the soil thus improved be compared 

 with any of the preceding soils that are mentioned as fitted for the 

 growth of the superior perennial grasses, it will appear to be still 

 very far from their natural composition, and proportionally less 

 adapted to the growth of these grasses. Even to bring it near to 

 the nature of the sandy loam (No. VI.), it would require 800 load 

 per acre : therefore, though this soil is unfit for the growth of the 

 superior grasses, it is capable of great improvement for the pro- 

 duction of grain or bulbous crops, by the application of clay and 

 calcareous matter ; it will thereby require less manure, and bettej 

 sustain the effects of a continuance of dry weather. 



The rich siliceous soil may have its nature changed, to resemble 

 that of the sandy loam, by the application of two parts of clay to 

 twenty-nine of soil, or 120 load to the acre. 



The above facts and observations may likewise shew, in some 

 measure, one out of many of the very useful practical purposes to 

 which the results of a chemical examination of soils may be made 

 subservient. 



The subsoil is of as much importance in determining the fitness 

 or unfitness of a soil for the growth of the superior grasses, as the 

 nature of the surface soil ; and, indeed, when it is considered that 

 the latter may have its nature completely changed, under favour- 

 able circumstances, with little trouble and at a moderate expense, 

 while the nature of the subsoil can only be partially corrected 

 under any circumstances, it may therefore be said to be of the 

 first importance in this inquiry. 



