PHYSICAL PROPERTIES OF THE SOIL. 405 



sition of the enriching matter with which its waters are charged. 

 The effect of too much Avater is to reduce the temperature of 

 the soil, to obstruct the access of the external air to the roots 

 of the plants, and, in fact, to macerate and destroy the texture of 

 the finest kinds of herbage. Perhaps it would be a more simple 

 statement, and equally just, to say that the aquatic plants are, 

 with some exceptions, not adapted to the nourishment of animal 

 life, and that those which are most suited for the food of man 

 or beast, are not suited to be grown under water. Water is of 

 great importance to their sustenance and growth. They cannot 

 live without it ; but they cannot live in it. As to the human 

 being, it may be of the highest benefit, both as an internal and 

 external application ; but there is soon an end to the matter when 

 man is plunged into water, and kept under it. 



All hope of cultivation or improvement must be abandoned, 

 where land is under water any considerable portion of the time, 

 or where it is fully saturated with water, like a sponge. 



2. POWER TO ABSORB MOISTURE IN A SOIL. I may remark, 

 in the next place, that the fertility of a soil very greatly depends 

 upon the power of the soil to absorb and to retain moisture. 

 Some very distinguished men have maintained that the fertility 

 of a soil may be measured by this power, an opinion which, it 

 may be said, (without meaning a pun.) has much ground to rest 

 upon, but which cannot be admitted without considerable quali 

 fications. Moisture and wetness are in this case to be carefully 

 distinguished. A soil consisting almost wholly of sand possesses 

 no retentive powers ; and though of all other soils the most 

 absorbent, yet the water passes through it as through a sieve. 

 Clay, on the other hand, is extremely retentive of water, often to 

 the prejudice of the vegetation which grows upon it. Liebig. 

 in a recent treatise upon artificial manures, to which I have 

 already referred, seems to be of opinion that the system of drain 

 age now prosecuted with so much enterprise in England may be 

 carried to an injurious extent, so as to induce the too rapid pas 

 sage of the soluble manures which are applied, and before they 

 can be taken up by, or have performed their proper office to, the 

 growing plants. As every thing which this distinguished gen 

 tleman asserts is now deemed oracular in the agricultural world, 

 1 will quote his observations at large. 



