SALT AS A MANURE. 37 



are concerned, that in most cases of experiments with salt, where 

 negative* results have been obtained, the soil might be reason- 

 ably suspected as having contained already a sufficient amount 

 of soda compounds and of chloride of sodium to answer all 

 practical purposes. All these recommendations of a direct use 

 of salt as an efficient fertilizer have one important feature in 

 common, namely, they caution to use but little at a time, to 

 apply it in a finely divided state, and to use it only at intervals 

 of years. As directly injurious effects on the other hand are 

 pointed out : its serious influence, for instance, on the tobacco 

 leaf and on the juice of the beet-root. It is claimed {Nesslar') 

 that its presence interferes with a ready combustion of the 

 former, favoring its charring, an effect in which it acts quite 

 reverse to potassa compounds ; in the case of the juice of beet- 

 roots it has been proved ( Grouven) that it increases, in a con- 

 siderable degree, its percentage of soluble saline compounds, 

 and thus reduces the value of the beet juice for the manufac- 

 ture of sugar. The fact that larger quantities of salt are death 

 to our common flora, and that it merely supports a vegetation 

 of its own, becomes at once manifest to those who glance at the 

 vegetation in the immediate vicinity of salt-springs and marine 

 inlets. In sight of these statements we are obliged to sum up 

 our case thus far in the following verdict : the direct use of salt 

 alone, as an artificial fertilizer, requires great precaution in the 

 manner of its application, and in the selection of crops, for its 

 beneficial effects seem to be due in a great measure at least to 

 its indirect action. 



More detailed and well planned inquiries of a later date con- 

 cerning the causes of the peculiar workings of the salt tend to 

 confirm the previous verdict ; they gave us besides, some valu- 

 able information in other directions. Our whole system of 

 manuring our farm lands is based mainly upon the principle to 

 restore to the soil those substances which we carry off by our 

 crops in larger proportion than nature can supply. The im- 

 portance of an artificial fertilizer is therefore due to its rate of 

 consumption. Numerous analyses of soil have taught us that 

 soda and potassa compounds are almost invariably accompany- 

 ing each other, and are in most cases more or less constant 

 admixtures of the soil. Thousands of analyses have demon- 



* These localities were along the seashore, and within access of oceanic spray, etc. 



