LIME AND MISCELLANEOUS FERTILIZERS 22/ 



The indirect action of land plaster upon western 

 prairie soils in liberating plant food, particularly potash 

 and phosphoric acid, is unusually marked. Laboratory 

 experiments show that small amounts of gypsum are 

 quite active in rendering potash, phosphoric acid, and 

 even nitrogen soluble in the soil water. 5 Occasionally 

 applications of superphosphate fertilizers give large 

 yields, due to the gypsum which they contain, and not 

 to the phosphorus. 



267. Quicklime and Slaked Lime. When it is de- 

 sired to correct acidity, slaked lime is used. Air-slaked 

 lime is not so valuable as water-slaked lime. Quick- 

 lime cannot be used on land after a crop has been 

 seeded. Both slaked lime and quicklime should be 

 applied some little time before seeding, and not to the 

 crop. The action of quicklime upon organic matter 

 is so rapid that it destroys vegetation. Slaked lime is 

 less injurious to vegetation. 



268. Pulverized Lime Rock. In some localities pul- 

 verized lime rock is used. It may be applied as a top 

 dressing in almost unlimited amounts. It is most 

 beneficial on light, sandy soils, where it performs the 

 function of fine clay as well as promoting chemical 

 action. Acid soils also are benefited by its use. Not 

 all soils are alike responsive to applications of lime- 

 stone, and before using it is best to determine to what 

 extent it is needed. There are no ordinary conditions 



