20 THE SOIL OF THE FARM. 



dominance in them either of sand, clay, or lime, as sand 

 loams, or clay loams, etc. Soils are also popularly desig- 

 nated from their texture as light or heavy, porous or im- 

 pervious; from tlieir relations to heat and moisture as 

 wet or dry, cold or warm; and from their measure of fer- 

 tility as rich or poor, fertile or infertile, etc. Again, the 

 class of croj^s respectively best adapted to each, has led to 

 clays being spoken of as wheat and bean soils, and friable 

 soils as barley and turnip land. 



The Composition of tlic Soil is one of the conditions 

 on which the fertility of a soil depends. 



On this composition depends its supply of plant food. 

 Fertility does not altogether depend on the quantity of 

 organic matter i^resent in the soil. There are some allu- 

 vial soils nearly destitute of organic matter, and yet of 

 almost inexhaustible fertility; and there are peaty soils 

 which are rich in organic matter, yet very barren. The 

 organic matter of the soil, however, is of great value. 

 It is constantly yielding by its decay matters which 

 nourish the organic parts of the plant, and it is setting 

 free, little by little, the earthy matters of its own ashes. 

 It is also, by its decay, inducing chemical changes which 

 tend to set free other matters held in combination in tlie 

 particles of the soil. It renders clay soil more friable, 

 and sandy soils more retentive of substances in solution; 

 and these are certainly great uses. 



The mineral matter of the soil is of equal importance. 

 All naturally fertile soils contain a notable ([uantity of 

 each of the different mineral substances which have been 

 named, which are indeed essential to fertility, for a soil 

 destitute of any one of them is more or less barren : fer- 

 tility being limited by the minimum of anyone necessary 

 ingredient, even though the maximum of the others be 

 present. 



However fertile a soil may be, not more perhaps than 



