Salt As A Fertilizer

Salt is but little used now by commercial asparagus growers, though it

has been recommended for this crop from time immemorial. About the

principal advantage to be derived from its use is that of killing weeds

without injuring asparagus, although it may be applied in sufficient

quantities to injure the asparagus. The indirect fertilizing value of

salt is mainly due to the fact that it has the power of changing

unavailable forms of plant food into available forms; but this object

may be secured cheaper and better by the use of kainit. In sandy soils

it may encourage the supply of moisture, but on naturally moist and

retentive soils heavy dressings of salt may do more harm than good.



Much of the benefits to asparagus for which salt gets credit is its use

in a small way in the home garden, due to the fact that not dry salt,

but the brine and residue of the pork and corned beef barrels is applied

to the asparagus beds. This brine is rich in animal matter extracted

from the meat, and usually also in saltpeter, which has been used in

pickling. The latter substance alone, without the addition of salt,

exerts a strong fertilizing effect upon the plants.



After a series of carefully conducted experiments by Mr. Charles V.

Mapes, he writes:



"Salt was only effectual as a fertilizer in proportion as the soil

contained accumulated supplies of plant food, either from previous

manurings or from natural strength. Asparagus, unlike nearly all other

crops, will stand almost unlimited quantities of salt without injury. It

also thrives near the seashore, and it was therefore generally believed

that liberal quantities of salt were a necessity to its successful

growth. Experience has shown, however, that its presence is not at all

necessary for its growth, and that the reason that a bed to which salt

has been applied shows quickened and improved growth is that the salt

dissolves out of the soil plant food which, without the presence of the

salt, would have become too slowly reduced to available condition for

producing good crops. The salt acted practically as a stimulant and

added nothing except chlorine and soda, neither of which in any

considerable quantity is essential for growing this crop. It is this

dissolving action that takes place in the soil whenever any soluble salt

or fertilizer, like kainit, potash salts, acid phosphates, etc., be

applied to the soil, that is often mistaken for a manuring one. The

result is an exhaustion, not a strengthening, of the soil. The crop is

grown at the expense of the limited supply of food that the soluble salt

can act upon. The fertilizer has acted practically as a stimulant."