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solution, to percolate through a stratum of arable 

 soil, we fail to recover from the water, after its 

 passage through the soil, the elements which it 

 contained in solution. This power of the soil to 

 abstract from their solutions the elements of plant- 

 food, is ascribed to a peculiar force of attraction, 

 which may be called the capillary absorbing power 

 of the soil. 



This faculty is of the greatest importance, and 

 seems to be specially bestowed on the soil for the 

 purposes of agriculture. For, were it otherwise, all 

 the elements of plant-food which became soluble in 

 water would be carried away into the subsoils, and 

 thence into the rivers, leaving the soil itself incapable 

 of supporting vegetable life. According, then, to 

 this provident law of nature, the pores of the surface- 

 soil attract the elements of plant-food immediately 

 they become soluble. 



Each particle of earth has a certain point of 

 saturation ; when this is attained, it loses all 

 further absorptive power, and passes the unchanged 

 solution on to the next particle ; but it regains this 

 power when the nutritive processes of plants dimi- 

 nish the store of these elements. The action of 

 water as a solving power ceases as regards these 

 absorbed elements of plant-food ; the physical force 

 of attraction prevents their being dissolved again, 

 until another and stronger power counteracts this 

 attraction and restores them to a state of solubility 



