300 Soda- Salts in Agriculture. 



Way, and other chemical authorities, Avho have failed to find 

 soda in the ashes of some crops and only insignificant quantities 

 in others. 



It is further worthy of notice that whilst the amount of phos- 

 phoric acid or potash in our crops within certain limits varies 

 but little, the proportion of common salt in green crops and 

 grass, and cereals in an unripe condition, appears to be regulated 

 entirely by accidental circumstances and to vary greatly. Thus 

 in land like the salt-marshes the herbage is richer in this con- 

 stituent than in upland districts, and on this account more 

 relished by cattle than ordinary herbage. Again, mangolds that 

 have received a heavy dressing of salt invariably contain a good 

 deal of salt, more especially in their leaves, whilst roots grown 

 without salt are comparatively poor in it. 



The difference between potash and soda in this respect is 

 striking. No plant as yet has been found in which potash was 

 entirely absent, and though a soil may contain but little of this 

 alkali, plants have the power of extracting it and assimilating it 

 — that is, using it for the building up of their own organism. Soda 

 and its combinations, on the other hand, when present, occur in 

 variable proportions in the sap of plants. Soda compounds do 

 not appear to enter into such intimate organic combinations with 

 carbon, hydrogen, nitrogen, and other elements, as potash and its 

 combination. It is worthy of notice that common salt never 

 occurs in perfectly ripe seeds, such as the grain of wheat, barley, 

 oats, even when the land upon which they are grown has been 

 heavily top-dressed with common salt, and the analysis of the 

 whole plant, root, stem, leaves, and unripe seed, shows its pre- 

 sence in considerable quantities. Common salt, and soda-salts in 

 general, as it would appear, circulate in the plant, assisting, in all 

 probability, the assimilation of other inorganic or soil consti- 

 tuents without becoming themselves integral parts of the living 

 plant. 



It may further be mentioned that Professor Knop of Leipzig 

 has succeeded in growing and maturing peas, beans, Indian 

 corn, oats, barley, wheat, and other plants, in watery solutions 

 from which he excluded all salts of soda. Lastly, it is well 

 known to every practical agriculturist that soda compounds as a 

 class certainly do not belong to our most efficacious manures ; 

 and it is certain that the beneficial effects which nitrate of soda 

 and a few other soda-salts produce are mainly due to their acid, 

 and not to their basic constituents. 



In the preceding remarks I have sufficiently stated the reasons 

 which induce me to regard soda as a non-essential ash-constituent 

 of plants. I have dwelt rather longer on this matter than 

 may be deemed necessary, because I think the time has arrived 



