60 



INORGANIC SUBSTANCES IN SOILS. 



TABLE FIRST. 



It will at once be noticed, that these are the very 

 substances which were named and described when we 

 were upon the inorganic part, or ash, of plants. To 

 this coincidence I shall return in the next chapter. 



At the head of the first column is named organic 

 matter; this has already been disposed of. The other 

 substances making up the inorganic part, follow in 

 different proportions, the silica being largest. It will 

 be seen that these three soils are different in their 

 qualities, one being fertile without manure, another 

 fertile with the addition of manure, and last quite 

 barren. Every one at all conversant with agriculture, 

 knows that these differences in soils actually exist. 

 We find occasionally, though not often, tracts of large 

 extent, where the most exhausting crops may be 

 grown for many years in succession without the aid 

 of manure, their power of production not seeming to 

 decrease even under such severe cultivation. Now 



