220 The Soil— Its Properties, etc. [May, 



and they possess this power in the greatest degree if they be alumi- 

 nous. 



If the silicious or sandy particles are in excess, sterility is the 

 consequence. Neither must the soil be too much comminuted ; a 

 certain proportion of coarse particles seems to be requisite. No one 

 ingredient should be in excess in any fertile soil, not even of organ- 

 ic matters. So that the best soil for general purposes is that where 

 an equable admixture of the general ingredients is present, with a 

 portion of the particles in a state of minute comminution. Much of 

 the fertility of soils depends upon their power of absorbing moisture 

 from the air. When this power is great, the plant is supplied with 

 moisture in dry seasons, and the effects of evaporation during the 

 sunshine is compensated by the absorption of moisture at night. — 

 Stiff clayey soils which absorb a great proportion of rain water, are 

 not however, the best suited for absorbing it in dry weather, as the 

 surface becomes hard, and separates into deep fissures, which assist 

 the evaporating effects from the interior. The best absorbing soils 

 are those in which there is a due admixture of sand, clay, and lime, 

 with animal or vegetable matter, and of lose and light texture, 

 freely permeable to the air and moisture. 



Carbonate of lime, and animal and vegetable matter, are highly 

 useful in this respect to soils ; they impart an absorbent power with- 

 out giving the soil too great tenacity. The absorbent power of soils 

 ought to be adapted to the climates. A sandy light soil will be more 

 productive than a deep clayey one, and the contrary. The subsoil 

 also has great effect in modifying the quantity of moisture. Shal- 

 low soils situated on a gravely base, soon lose their moisture and 

 fertility, and are the most difficult to preserve, or once exhausted to 

 recover ; while deep clay, subsoils retain moisture for a long time, 

 and are the most lasting and improveable. A soil exposed for cen- 

 turies to all the influences which effect the disintegration of rocks, 

 but from which the alkalies, thus rendered soluble, have not been 

 removed, are able to afford for many years, the means of nourish- 

 ment to vegetables requiring a considerable amount of alkalies for 

 their growth ; but it must gradually become exhausted, unless those 

 alkalies which have been removed are again replaced ; a period 

 therefore will arrive when it will be necessary to expose it from 

 time to time to a further disintegration, in order to obtain a new 

 supply of soluble alkalies. 



LiEBiG says, the first colonists of Virginia found a soil rich in 



