[371] SCIENTIFIC MANUAL. &6 



be mingled by the action of frosts and rains, with the sur- 

 face sand. 



The clay fills the interstices between the grains of sand, 

 increases its retentive and absorptive power for moisture 

 and gases, improves its capillary action, and facilitates root 

 action. The addition of vegetable matter in conjunction 

 with the admixture of clay, will more effectually correct 

 its mechanical defects. 



If clay is not in reach of the plow, the use of lime with 

 vegetable matter is the most economical and effectual 

 means to be employed to ameliorate the defective mechan- 

 ical condition of coarse sandy soils, and thus increase their 

 productive capacity. 



Clay soils are called heavy on account of the difficulty at- 

 tending their cultivation, though their specific gravity is 

 less than that of sandy soils, which are called light, on ac- 

 count of the facility with which they are cultivated. 



The stiffness and tenac.ity of clay soils is remedied by an 

 application of lime and vegetable matter, which serve as 

 divisors, preventing the adhesion of the particles under 

 the influence of either drouth or excessive wet. 



Clay soils are often injured by being plowed when too 

 wet, especially in the spring, when drying winds, and a 

 baking sun, cause a harshness, which continues through- 

 out the growing season, and often, in our mild climate, 

 lasting through several years. 



Though more difficult to cultivate than sandy soils, clay 

 has a much greater capacity for absorbing and retaining 

 moisture and fertilizing gases from the atmosphere. 



Clays deficient in vegetable matter, or without an ad- 

 mixture of sand, often contract, when dry, to such an ex- 

 tent as to break the rootlets of plants, and thus cause seri- 

 ous injury. This does not occur in sandy soils or loams. 



Dry, pulverized clay may be advantageously used as an 

 absorbent in stables, to fix fertilizing gases, and especially 

 ammonia, which would otherwise escape into the atmos- 



