112 THE ESSENTIALS OF AGRICULTURE 



minerals, makes the plant food available. Therefore on stingy 

 soils quicklime may be the form needed ; on friendly soils lime- 

 stone may be more satisfactory and is always safer. 



140. How and when to apply lime. Quicklime is usually 

 thrown into small piles in the field and covered with moist soil. 

 In the course of a few days it absorbs sufficient water from the 

 soil to slake it and falls to a fine powder, after which it can be 

 scattered. In some sections the quicklime is ground to a meal, 

 scattered with a special spreader, and allowed to slake on the 

 soil. Lime in any form is applied on plowed land and should be 

 thoroughly mixed into the soil. Quicklime is applied at the rate 

 of from 20 to 40 bushels of 75 pounds each, and ground lime- 

 stone is applied at the rate of from I to 3 tons per acre, 2 tons 

 being the usual amount. In a rotation lime is usually applied 

 just before seeding to wheat. This is especially to be recom- 

 mended if clover is to be sown on the wheat the following spring. 



141. Do commercial fertilizers and lime hurt the soil ? Quick- 

 lime has long been regarded as a soil stimulant in the sense that 

 it helps to release plant food contained in the soil. It should not 

 be used except in a rational system of crop rotation and where 

 manures have a prominent part ; otherwise, it is likely to be 

 positively hurtful to the soil. This idea is well expressed in 

 the old saying "The use of lime enriches the father and 

 impoverishes the son," but this statement applies less to lime- 

 stone than to lime. 



It is a common notion that commercial fertilizers, too, act as 

 soil stimulants and that their continued use is injurious to the 

 land. They are, however, in no sense soil stimulants, and their 

 value lies not in unlocking food already contained in the soil, 

 but in the plant food they themselves supply. If the farmer is 

 careful to maintain a proper supply of organic matter in the soil 

 through the use of barnyard and green manure, he may safely 

 use commercial fertilizers indefinitely. The rational use of 

 commercial fertilizers requires that they be used in connec- 

 tion with, and not as substitutes for, green crops and barnyard 

 manures. 



