24 AMERICAN AGRICULTURE. 



ble nutrition. Gypsum is also a valuable manure for peaty 

 soils. 



SUBSOILS AND THEIR MANAGEMENT. 



The efficiency of soils in producing good crops, depends 

 much on the subsoil. If this consists of impervious clay or 

 hard-pan, which prevents the drainage of the water, it is 

 evident, the accumulation of heavy rains will materially in- 

 jure the vegetation above ; for it is certain, that while no- , 

 thing is more essential to productiveness than an adequate 

 supply of moisture for the roots, nothing is more injurious 

 than their immersion in stagnant water. If this description 

 of subsoil be deep, the only remedy is thorough underdrain- 

 ing ; if shallow, the crust may be broken up with the subsoil 

 plow and gradually mixed with the surface soil, when the 

 water will readily escape below. 



A variety of plows have been constructed for this purpose ; 

 but unless it be intended to deepen the soil by an admixture 

 of manures, they must not be used for bringing up the 

 subsoil too rapidly, to mix with that on the surface. In ad- 

 dition to the more ready escape of water, thus secured by 

 breaking it up, the air is also admitted, which enables the 

 roots to strike deeper, and draw their nourishment from a 

 much greater depth. The increased distance through 

 which the roots penetrate, furnishes them with additional 

 moisture during a season of drought, thereby securing a lux- 

 uriant crop when it might otherwise be destroyed. This is 

 frequently a great item in the profit of the farmer ; as, be- 

 sides the increase of crop which follows a dry, hot season, 

 when a full supply of moisture is furnished, the product is 

 usually of better quality ; and the general deficiency of agri- 

 cultural produce, which ensues from seasons of drought, 

 makes his own more valuable. 



As a result of this practice, there is also a gradual increase 

 in the depth of the soil ; as the fine and more soluble parti- 

 cles of the richer materials above, are constantly working 

 down and enriching the loosened earth below. In time, 

 this becomes good soil ; and this, in proportion to its depth, 

 increases the area from which the roots derive their nutri- 

 ment. So manifest are the advantages which have followed 

 the use of subsoil plows, that they have been extensively 

 introduced of late years, among the indispensable tools of 

 the better class of agriculturists. 



