80 Practical Farming 



their soil have jumped to the conclusion that all they have 

 to do to make their soil rich and productive is to keep 

 using Hme on it, not reahzing that the effect of the Hme 

 is to make available the supply of potash that already 

 exists in their soil. Hence, there came about the proverb 

 that "lime enriches the father and impoverishes the son." 

 While this is true when lime is incautiously used, with the 

 idea that it is simply a manure, lime is of great value in 

 improved agriculture, as we shall see later. 



Plants cannot grow in any soil which does not contain 

 nitrogen, phosphorus, potassium, calcium, iron, magne- 

 sium, sulphur, sodium (for some species), chlorin, and 

 sihcon. Most of these exist in inexhaustible amounts in 

 all cultivable soils. Those which are liable to become 

 exhausted or deficient from cultivation are nitrogen, 

 phosphorus, potassium, and sometimes calcium. The 

 crops we grow take these in larger amounts than other 

 elements. If any one of these is in the soil in a smaller 

 percentage than a proper development of the plant re- 

 quires, the crop will be smaller even though the other 

 elements are in full supply. The soil that has a very 

 small percentage of potassium and phosphorus may have 

 a large supply of nitrogen; and the plants may make a 

 rank growth and yet fail to perfect grain, since the per- 

 fection of the grain depends on these elements. In like 

 manner there may be a full supply of these available and 

 yet a deficiency of nitrogen, and the plants will make a 

 feeble . growth, and lack the healthy green of flourishing 

 crops. Hence it is necessary that the plant food in the 

 soil shall be as well balanced as it has been found neces- 

 sary to balance the rations for our domestic animals. 



