62 



ON INCREASING THE GROWTH 



in a less degree than those of potash. This may be 

 explained from the fact, that plants, as the examina- 

 tion of their mineral constituents has already shown, 

 absorb soda only in very inconsiderable quantities 

 from the soil, although for the most part richer in 

 soda than in potash. For this reason the salts of 

 soda possess, as elements of manure, a lower value 

 than those of potash, and are seldom wanting to 

 plants, inasmuch as their diffusion is almost univer- 

 sal. By high winds and storms, sea-water con- 

 verted into fine spray, and with it common salt, is 

 scattered widely over the earth, and the latter ingre- 

 dient is found, in greater or smaller quantities, in al- 

 most every spring. If the farmer believes that the 

 application of salt will be beneficial to his fields, he 

 wdll proceed most advantageously by mixing the salt 

 with the food of his cattle. In this way he will pro- 

 cure a manure abounding in salt, and reap a two- 

 fold benefit. The so-called " manuring salt " of the 

 salt-boiler consists in great part of gypsum, and its 

 action upon the land may in many cases be ascribed 

 to this substance rather than the salt. 



4. Phosphoric Acid. This, next to nitrogen, must 

 be pronounced the most important and valuable con- 

 stituent of manure ; because upon it ihe formation of 

 the seed essentially depends, and because it is found 

 only in scanty quantities in the soil, although every- 

 where present. If plants cannot absorb it in suffi- 

 ciency from the ground, they bear little seed. The 

 gain in quantity and weight of grain after manur- 



