Using Salt as Chemical Fertilizer or Garden Manure?

Salt as Chemical Fertilizer or Garden Manure

Common salt (sodium chloride) is probably the oldest chemical fertiliser and yet little or nothing seems to be known about how and why it acts. In fact, sometimes it doesn’t and certainly an excess will kill plants as effectively as any weedkiller. In this connection it is rather interesting to note that if a heavy application of salt is used as a weedkiller, after a period of time the weeds come back with double their original vigour.

chemical fertiliser

The recognition of the manurial uses of salt dates back to the very earliest recorded times. There are many allusions to its use in the Old Testament, and again in the New, whilst according to writers such as Pliny, it was well known as a manure in Roman Italy. The Persians and the Chinese are recorded as having used it from time immemorial as a fertiliser, particularly for dates.

It seems, too, on looking through ancient books that it was used for a number of purposes some beneficial and some as punishment. For example, it was customary for  the ancient Jews and the Romans after a total conquest of a city or a nation, to spread salt thickly on the fields, after razing the buildings. Having access to considerable quantities in the ‘salt’ sea, one could follow their logical reasoning.

It has been described as an insecticide, a germicide and as an antiseptic. The Romans also used salt to spread on a spot where some great crime had been committed. I have traced its use in England back for hundreds of years and Lord Bacon had a lot to say about it – whilst Coke of Norfolk used it in considerable quantities.

Before 1914, large quantities of salt together with herring heads and insides, were carted on to the fields, especially where sugar beet were grown. With this in mind, my father used to tell me stories of two old village rustic characters, ‘Old’ Bob Davidge and ‘Old’ Betty Carlidge, who used to stock up on salted herrings when they were scattered on the land. Old Bob, a hedger and ditcher, used to toast many a herring over his breakfast fire and most appetizing they smelt too on a cold frosty morning.

I have been intrigued with the use of salt in the garden and on various crops ever since that time. Broadly, my experience has been that it makes poor land poorer but heavily-manured land better. It assists in the flocculation of fine particles, much in the same way as lime, but it seems to act perhaps more as a digestive by making solutes (solution of chemicals) more readily available and more easily assimilated.

It appears to me that the action of salt as a manure is indirect and not direct. This is in a line with sugar and yeast residues which are often used to put girth on exhibition leeks. Salt, of course, went out of favour as a fertiliser with the introduction of more precise chemical fertilisers but for some crops I still use it, particularly on asparagus and beetroot. I also use it on over-wintering brassicas such as sprouts, savoys and cabbage, as well as spring-maturing broccoli.

The old gardener’s measure was a cubic inch of salt to the square yard of soil. The cubic inch was measured by making a square hole in a potato or turnip; I used a heaped teaspoonful. The main advantage as far as I’m concerned seems to be that it acts a bit like anti-freeze and makes the foliage less liable to damage by the alternate freezing and thawing which plays havoc with overwintering brassicas.

I found the following quote in an old book:

‘common salt – chloride of sodium – applied in the spring at the rate of 20 bushels per acre has been found very beneficial to asparagus, broad beans, lettuce, onions, carrots, parsnips, potatoes and beets. Indeed, its properties are so generally useful, not only as promoting fertility but as to destroying slugs, that it is a good plan to sow the garden every March with this manure’.

The flower garden is included in this recommendation:

‘for some of the best practical gardeners recommend it for the stock, hyacinth, amaryllis, ixia, anemone, colchicum, narcissus and ranunculus.  And in the fruit garden it has been found beneficial to almost every one of its tenants, especially the cherry and the apple.

There must be fertilising matter present in the soil if it is to act favourably.  Studying the experience of Norfolk farmers of 100 years ago, it would seem that by greed they ultimately did more damage than good. They found, as many other people have found, that a small quantity of salt applied with heavy dressings of manure produced beneficial results on virtually all crops. They then reduced the quantity of manure and sold this and increased the quantity of salt, which was cheap, the result being that the crops and the soil became poor, hence the old jingle ‘salt and lime without manure makes both land and farmer poor’.

In the early days of artificial fertilisers, salt was often used as an adulterant, especially in the fertiliser known as muriate of potash, sometimes described as agricultural salt. Salt can be found naturally in virtually everything, animal and vegetable alike. More and more we are finding out that it is the tiny microscopic amounts of a substance that can make or mar man, animal or vegetation and so it would appear to be the case with salt.


23. August 2010 by Dave Pinkney
Categories: Garden Management, Manures and Fertilisers, Soil Cultivation | Tags: , , | Comments Off on Using Salt as Chemical Fertilizer or Garden Manure?

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