346 CAUSES OF THK FAILURE OF COMMON SALT. 



Cause of these failures. — It is not, indeed, to be wondered at, that 

 amid conflicting statements as to its value, the practical farmer should 

 have hesitated to incur the trouble and expense of applying it — so long 

 as no principle was made known to him by which its application to this 

 soil rather than to that, and in this rather than the other locality, was to 

 be regulated. 



1°. We know that plants require for their sustenance and growth a 

 certain supply of each of the constituents of common salt, which supply, 

 in general, they must obtain from the soil. If the soil in any field 

 contain naturally a sufficient quantity of common salt — or of chlorinv'i 

 and soda, in any other state of combination — it will b^nnecessary to 

 add this substance, or, if added, it will produce no benencial effect. If, 

 on the other hand, the soil contain little, and has no natural source of 

 supply, the addition of salt may cause a considerable increase in the crop. 



Now there are certain localities in which we can say beforehand that 

 common salt is likely to be abundant in the soil. Such are the lands 

 that lie along the sea coast, or which are exposed to the action of pre- 

 vailing sea winds. Over such districts the spray of the sea is constantly 

 borne by the winds and strewed upon the land, or is lifted high in the 

 air, from which it descends afterwards in the rains.* This considera- 

 tion, therefore, affords us the important practical rule in regard to the 

 application of common salt — that it is most likely to he beneficial in 

 spots which are remote from the sea or are sheltered from the prevailing 

 sea winds. 



It is an interesting confirmation of this practical rule, that nearly all 

 the successful experiments above detailed were made in localities more 

 or less remote from the sea, while most of the failures on record were 

 experienced near the coast. This consideration, it may be hoped, will 

 induce many practical men to proceed with more confidence in making 

 trial of its effects on inland situations. It is very desirable that the 

 value of this practical rule, which I suggested to you in a former lec- 

 ture (see p. 190), should be put to a rigorous test.f 



2°. But some plants are more likely to be benefitted by the applica- 

 tion of common salt than others. This may be inferred from the fact 

 that certain species are known to flourish by the sea-shore, and where 

 they grow inland to select such soils only as are naturally impregnated 

 with much saline matter. Observations are still wanting to show which 

 of our cultivated crops is most favoured by common salt. It is known, 

 however, that the gas of salt marshes is peculiarly nourishing, and is 

 much relished by cattle, and that the grass lands along various parts of 

 our coast produce a herbage which possesses similar properties. It is 

 also said that the long tussaclc grass which covers the Falkland Islands, 



* Dr. Madden has calculated that the quantity of rain which falls at Penicuick in a year, 

 brings down upon each acre of land in that neighborhood more than COO lbs. weight of com- 

 mon salt. This would be an enormous dressing were it all to remain upon the land. 

 Heavy rains, however, probably carry off more from the soil than they impart to it. It is 

 the gentle showers that most enrich the fields with the saline and other matters they con- 

 tain. 



t A number of failures are described in the sixth volume of the " Transactions of the 

 Highland and Agricultural Society." Dr. Madden has recently shown that to nearly all 

 these cases the above principle applies— the farms on whic ■, they were tried being more or 

 less freely exposed to the \tiviis from the east or west sea —Quarterly Journal of Agri- 

 culture, Sept. 1842, p. 574. 



