Miscellaneous Fertilizing Materials 115 



have deposits of marl upon their own farms, or within 

 short distances of them, or can secure it at a low price, 

 its application is a desirable method of improving land. 



The results from the use of marl are frequently due as 

 much to the improvement of the physical condition of 

 soils as to the fertility constituents added. Marl may be 

 carted and spread upon the land when other work of the 

 farm is not pressing, thus making it possible to get a con- 

 siderable addition of fertility at a small expense. 



Agricultural salt. 



Agricultural salt which is chiefly common salt or sodium 

 chlorid, is frequently used as a manure. It supplies 

 no essential plant-food constituent. Its value is still 

 disputed, though it is admitted that where its use is 

 favorable, it is due to indirect action in aiding the decom- 

 position of animal and vegetable matter, increasing the 

 absorbing power of soils, and by its reaction with lime 

 acting as a solvent for phosphates. Its most important 

 function is in bringing the reserves of insoluble potash 

 in the soil into solution. 



Upon heavy soils, the use of common salt may prove 

 injurious. If carbonate of lime is present in the soil, com- 

 pounds are formed which deflocculate clay and render it 

 wet and sticky. 



In view of the advantages enumerated there is no good 

 reason for paying from $4 to $6 a ton for this substance, 

 when practically the same effect can be obtained from the 

 salt contained in the crude potash salt, kainit, one-third 

 of the total weight of which is common salt. This, too, 

 may be had free of charge, or for the handling, as the 

 market price of the kainit is based upon its content of 

 potash. 



