Again, the very fact that salt acts as an antiseptic may serve to
explain its beneficial action in certain cases where it prevents
rankness of growth. No doubt this was its function when applied along
with Peruvian guano. This it might do by preventing too rapid
fermentation (nitrification) of the manure, or by actually weakening the
plant. Its action when applied with farmyard manure may also be similar.
But while its effect in many cases may be towards retarding
fermentation, on the other hand its action, when applied along with lime
to compost-heaps, is towards promoting more rapid decomposition.
Probably a reaction takes place between the lime and the salt, the
result of which is the formation of caustic soda.

Such are some of the ways in which salt may act. It must at once be seen
how its action in one case will be favourable and in another case
unfavourable. There must be fertilising matter present in the soil if it
is to act favourably. Again, it will only be under such circumstances,
where rankness of growth is likely to ensue, that its antiseptic
properties will act favourably and not unfavourably.

_Best used in small Quantities along with Manures._

Probably it is for these reasons that its action has been found to be
most favourable when applied along with other manures and not alone.
Applied along with nitrate of soda, as is commonly done, it doubtless
increases the efficiency of the nitrate. Some plants seem to be
undoubtedly benefited by salt: of these flax may be mentioned. The
application of salt to plants of the cabbage tribe seems also to be
highly beneficial. On mangels, along with other manures, it has also
been found to have a very favourable effect. But with many crops its
action has been proved to be less favourable.

_Affects Quality of Crop._

Although salt has often been found to increase the quantity of a crop,
the quality of the crop has been made to suffer. Its action on beetroot
has been more especially studied. The effect of its application is to
lessen the total quantity of dry matter and sugar in the plant. This has
been found to be the case both when the salt was applied alone and along
with nitrate of soda and other manures. On potatoes, again, its action
has been found to be deleterious, lessening their percentage of starch.
The deleterious action of chlorides on the quality of potatoes is also
seen when potassium chloride is applied. It is for this reason that
potash shoul