METHODS OF LIMING 115 



lime spreader may be used in applying lime to the field. Bags or 

 old grain sacks may be allowed to drag back of the delivery tubes 

 at the surface of the ground to prevent much of the disagreeable 

 cloud of dust for the driver and team. Pulverized limestone is 

 not caustic and is usually not so dusty. It can aso be hauled 

 directly from the car to the field and requires no extra handling. 

 Burned lime must be handled twice to accomplish the slaking and 

 spreading. 



Lime is usually spread on top of the plowed field, and should 

 rarely be plowed under. Its tendency is to work downward through 

 the soil too rapidly. Quick lime, or calcium oxide, should not be 

 applied long in advance of the time when it is to be used. Pulver- 

 ized limestone may be hauled at any time when teams are not 

 busy, as its loss upon the field is much slower. 



COMMERCIAL FERTILIZERS 



It is sometimes said in reference to rich humus soils of the 

 western prairie states that "They do not need commercial fertili- 

 zers." This might also have been said regarding the newly 

 cleared lands of the timber states farther east. But after soils 

 have been used by man for a generation or more they deteriorate 

 in the actual amount of available plant food. Analyses of old 

 soils usually show an abundant supply of potash and phosphate, 

 but little of them in available forms. The amount of potash and 

 phosphate is usually greater in heavy soils containing much clay or 

 silt. The nitrogen may have almost entirely disappeared unless 

 some system has been used for its special maintenance. 



Because of the deterioration of soils in long use for farming 

 purposes, it has usually been found very profitable to resort to 

 the use of commercial fertilizers. The greatest profit from their 

 use is usually found in the growing of special crops, such as truck 

 crops, cotton, tobacco and potatoes. Indeed when a farmer is 

 making a specialty of any particular crop he usually finds it very 

 profitable to use fertilizers. American farmers are using at the 

 rate of between 200 and 300 million dollars' worth annually. 



In one form or another commercial fertilizers contain nitrogen 

 or phosphoric acid or potash perhaps two or all three of them. 

 These are applied to the soils at the time the crops actually need 

 them for the purpose of directly feeding and stimulating the crops. 

 As a general rule they should not be used with the hope of perma- 

 nently improving the soil itself, except when they are used to 



