IQ2 SOILS AND FERTILIZERS 



condition of the soil. The physical action of lime 

 in 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 frequently 

 sufficient to warrant their use. 



257. 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 ferti- 

 lizer but simply an amendment and an indirect ferti- 

 lizer. 10 If used to excess it may get the soil in such 

 condition that plant food is not easily 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 injur- 

 ious effect upon the soil and is a valuable fertilizer, 

 especially where clover is grown with difficulty. 



MISCELLANEOUS FERTILIZERS 



258. Salt is frequently used as an indirect fertilizer. 

 Sodium and chlorine, the two elements of which it is 

 composed, are not absolutely necessary for normal 

 plant growth. When salt is applied to the soil and 

 the sodium undergoes fixation, potassium may be lib- 

 erated. An early experiment of Wolff illustrates this 



