CHAPTER 6 



Lime and other Soil Amendments 



Soils Need Lime^ — Lime is an essential element of plant food. Many- 

 plants are injured by an acid condition of the soil. Soil acidity is most 

 cheaply corrected by one of the several forms of lime. The beneficial 

 effects of liming have been demonstrated by the agricultural experiment 

 stations in a dozen or more of the states. Observations by farmers in all 

 of the Eastern and Southern States, and in the Central States as far west 

 as the Missouri River, show that on many of the farms soils are sour. 

 This sourness of the soil is due to a deficiency of lime, and often occurs 

 in soils originally rich in lime. 



Lime Content of Soils. — Soils vary greatly in their original lime 

 content. Some have very little lime to begin with. Others, such as the 

 limestone soils, are formed from limestone rocks, some of which were 

 originally more than 90 per cent carbonate of lime. The lime content of 

 soils is determined by treating them with strong mineral acids. This 

 removes all of the lime from the soil, and the content is then determined 

 chemically. The following table shows the lime content of a number of 

 typical soils in different parts of the United States: 



Lime Content (CaC0 3 ) per Acre 7 Inches of Soil in Some Typical Soils 

 of the United States. 



How Soils Lose Lime. — The greatest loss of lime from the soil is 

 due to leaching. Lime is slowly soluble in the soil solution, and is carried 

 downward by the gravitational movement of the soil water. The rate 

 of loss of lime in this way depends both upon the rate of solubility and 



(115) 



