284 



THE SOIL OF RICH ARABLE LAISDS. 



2°. Arable. — The following table exhibits the constitution of three 

 soils, celebrated for yielding successive crops of corn for a long period 

 without manure. 



100 



100 



100 



100 



Of these soils, the first had been cropped for 160 years successively, 

 without either manure or naked fallow. The second was a virgin soil, 

 celebrated for its fertility. The third had been unmanured for twelve 

 years, during the last nine of which it had been cropped with beans 

 —barley — potatoes — winter barley and red clover — clover — winter bar- 

 ley — wheat — oats — naked fallow. 



Though the above soils differ considerably, as you see, in the propor- 

 tions of some of the constituents, yet they all agree in this — that they are 

 not destitute of any one of the mineral compounds, which plants necessa- 

 rily require in sensible quantity. You will also observe how compara- 

 tively small a proportion of vegetable matter, less than half a per cent., 

 is contained in the fertile Belgian soil — a fact to which I shall by-and- 

 by recall your attention. 



3°. Soils which have a natural source of fertility. — Some soils, which 

 by their constitution are not fitted to exhibit any great degree of fertility, 

 or for a very long period, are yet, by springs or otherwise, so conslantly 

 supplied with soluble saline, and other substances, as to enable them to 

 jrield a succession of crops, without manure, and without apparent dete- 

 rioration. Such is the case with the following soil from near Rotlien- 



