LIME AND MISCELLANEOUS FERTILIZERS 201 



254. Physical Action of Lime. — The addition of 

 lime fertilizers to sandy soils improves their general 

 physical condition. Heavy clays lose their plasticity 

 when limed ; the fine clay particles are cemented 

 and act as sand, which improves the mechanical 

 condition of the soil. The physical action of lime 

 upon soils is well illustrated in the case of 'loess soils,' 

 which are composed of clay and limestone. The 

 lime cements the clay particles and forms compound 

 grains, making the soil more permeable, and more 

 easily tilled. The improved physical condition alone 

 which follows the application of lime fertilizers, is fre- 

 quently sufficient to warrant their use. 



255. Application of Lime Fertilizers. — Lime is 

 generally used as a top-dressing on grass lands at the 

 rate of 200 to 500 pounds per acre. Excessive appli- 

 cations are undesirable. Lime as gypsum is particu- 

 larly valuable when applied to land where crops are 

 grown which assimilate large amounts of lime. It 

 should be remembered that it is not a complete, but 

 mainly an indirect, fertilizer. 



If used to excess it may get the soil in such a con- 

 dition that no more plant food can be rendered avail- 

 able. A common saying is " Lime makes the father 

 rich but the son poor." 21 This is true, however, only 

 when lime is used in excess. When used occasion- 

 ally in connection with other manures, it has no inju- 

 rious effects upon the soil and is a valuable fertil- 



