THE LIMING OF THE SOIL 221 



than others, and this gives us a test for the lack of lime. If 

 red clover fails where it once grew, it is a sure indication that 

 lime should be applied to the soil. 



The sources of lime are limestone and gypsum, but the 

 limestone, or calcium carbonate, is more desirable. When 

 roasted, this changes into unslaked lime, the material that is 

 used on the soils. There it unites with the water, forming 

 slaked lime, which is rather soluble. In this way the lime can 

 be carried throughout the grains of the soil. A small applica- 

 tion of lime lasts for a long time. On the other hand, an ex- 

 cess of lime does no harm. 



In Section 163, Plant Roots, it will be learned that the roots 

 of growing plants give off an acid. Lime neutralizes this 

 acid. 



References : 



1. 1205:10. Acids in Soil Water. 



2. 1601 : 30. Effects of Lime on Soil. 



3 1605 : 126-128. Lime, its Functions and Forms. 



4. Farmers' Bulletin No. 77. The Liming of Soils. 



5. Farmers' Bulletin No. 259 : 7-9. Spreading Lime. 



6. Farmers' Bulletin No. 374 : 5-7. Inoculation and Lime for 



Alfalfa. 



7. Bureau of Plant Industry No. 71. Legume Inoculation and 



the Litmus Reaction of Soils, 



a. 1603 : 26. Action of Lime in ttie Soil. 



6. 1606 : 97-98. Lime as an Amendment. 



c. 1607 : 71. Action of Lime. 



d. 1610 : 64-67. Use and Application of Lime. 



e. 1611:146-147. Liming the Soil. 

 /. 1612 : 99-107. Liming the Land. 



Experiment 75. The Effect of Lime Acid Soils. 

 Apparatus: Beaker 150 c.c., battery jar 6"X8", ring 

 stand, burner, asbestos mat. 



