PRINCIPLES OF AGRICULTURAL CHEMISTRY 



In heavy clay soils, the fine clay particles are present in large 

 quantity. Such soils are very retentive of moisture, require 

 much labor in cultivation, are likely to be tough and sticky when 

 not ploughed at exactly the right time, are not easily penetrated 



UNITED STATES DEPARTMENT OF AGRICULTURE, 



)l VISI..N >F AGRICULTURAL SO 



THE TEXTURE OF A TYPICAL TOBACCO LAND AT HATFIELD. MASSA 



Par Cent of Gravel. Sand. Silt, and Clav in 2O Cirams of Subsoil 



DIAMETER OF THE GRAINS IN MILLIMETERS. 



Fig. 27. Physical analysis of a soil sample. Bureau of Soils. 



by water, and do not warm up rapidly in the spring. Twenty per 

 cent, clay particles usually make a soil difficult to work. 



Soils with much silt and little or no clay, are likely to adhere 



