100 DEPARTMENT OF AGRICULTURE GEORGIA. [386] 



primarily from minerals, are found in the ash of plants, 

 when they are burned with free access to the air. The 

 most important are potash, soda, lime, magnesia, phos- 

 phoric acid, sulphuric acid, silica, and chlorine. Of these, 

 phosphoric acid may be said to be always beneficial, as an 

 artificial application to the soil, potash generally, lime 

 often, soda, chlorine, and magnesia, for particular plants, 

 such as tobacco, beets, etc., and the others, never. 



Phosphoric acid is derived principally from animal bone, 

 phosphate rock, as found near Charleston, S. C, and in 

 various other parts of the globe, and from the decay of 

 animal and vegetable matters. Its principal office in plant 

 nutrition, seems to be to increase the production of fruit, 

 and especially seed, rather than stalk. By reference to the 

 Tables of Analyses, in the Appendix of this work, the 

 reader will see that it is an important constituent of the 

 ash of the seeds of all agricultural plants. 



Soda is derived, principally, from the chloride of sodium, 

 or common salt, which abounds in the waters of the 

 ocean, in salt springs, and in vast deposits of rock salt. It 

 is present in sufficient quantity, in most soils, for the pur- 

 poses of vegetaiton, but may be profitably supplied, as a 

 special fertilizer, to a few plants, such as tobacco, beets, 

 turnips,' carrots, etc. 



Salt (chloride, of sodium] is especially beneficial to cab- 

 bage and asparagus, and applied to gardens, in early win- 

 ter, is destructive of injurious insects. 



Nitrate of soda is found as an incrustation on the surface of 

 the earth, in Peru. It acts finely, when applied as a top- 

 dressing, on small grain and the grasses. 



Potash is used for agricultural purposes, in the various 

 compounds of potassium, which, uniting with carbonic 

 acid, forms carbonate of potash; with sulphuric acid, sul- 

 phate of potash ; with chlorine, chloride of potassium, 

 (muriate of potash); with nitric acid, nitrate of potash, ni- 

 tre, or saltpeter, and with silicic acid, silicate of potash.. 



