200 SOILS AND FERTILIZERS 



251. Quicklime and Slaked Lime. — When it is de- 

 sired to correct acidity slaked lime is used. Air- 

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

 Quicklime cannot be used on land after a crop has 

 been seeded. Both slaked lime and quicklime 

 should be applied some little time before seed- 

 ing and not to the crops. The action of quicklime 

 upon organic matter is so rapid that it destroys vege- 

 tation. Slaked lime is less injurious to vegetation. 



252. Pulverized Lime Rock. — In some localities 

 pulverized 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 perforins the 

 function of fine clay as well as being beneficial in its 

 chemical action. Not all soils are alike responsive to 

 applications of limestone, and before using, it is best 

 to determine to what extent it will be beneficial. 

 There are no conditions where limestone is injurious 

 to soil or crop. 



253. Marl. — Underlying beds of peat, deposits of 

 marl are occasionally found. Marl is a mixture of 

 disintegrated limestone and clay, and contains varia- 

 ble amounts of calcium carbonate, phosphoric acid, 

 and potash. When peat and marl are found together 

 they may be used jointly with manure as described in 

 Section 175. Many sandy lands in the vicinity of peat 

 and marl deposits would be greatly improved, both 

 physically and chemically, by the use of these materials. 



