Physical Properties Of Salt

Sun (Auckland), Volume III, Issue 922, 15 March 1930, Page 27

Physical Properties Of Salt

THE IMPORTANT PART THEY PLAY IN AGRICULTURE A T ONE TIME common salt was considered to be an essential factor in many branches of farming. It was used both as a manure arid a stock food. In view of this a recent article reviewing the agricultural uses of agricultural salt, published in the “Journal of the British Ministry of Agriculture,’’ makes interesting reading.

For many years common salt has been regarded as a useful fertiliser for certain farm crops, and a benelieial pbysi•al action upou tne soil has also been claimed for it. Early last century cases were reported in which salt appeared to be highly valuable as a manure. In 1817 Sinclair affirmed that whereas a dressing of farmyard manure gave a 40-50 bushel crop of wheat in a particular instance, the yield was increased to 70 bushels by a light dressing of common salt and to 90 bushels by a heavy dressing. By the middle of the century salt was used regularly for. mangels and for stock in some districts. I Experiments carried '-ut ou the estates ] of the Earl of Leicester i;» 1852-51 re- i suited in the no-salt plots giving for the three years 81 bushels more wheat and tiewt more straw than plots which had received salt. Eawes carried out trials of a more j exact nature. On land carefully chosen ! for the experiment, the sal! and no-salt plots were tested for soil differences by weighing the crops for three years before the salt wss applied. Iu addi- : % tion to the three y.*ars during which 'comparisons were made he*ween treated j and untreated plots, the plots were ! cropped and *he results observed, and j crops weighed for a further period of ; 10 years to detect any possible after- i effect of salt. At the end of 1G years Eawes concluded that there was no effect whatever from the use of salt in the careful and prolonged experiments. Use on Crops md Pastures. Salt is often included in manorial dressings for many’s. A liberal supply of potash is essential for a heavy rnanKel crop, and the beneficial action of salt js probably due to its power of increasing tlie supply of available potash in the soil. It was formerly believed that mangels benefited from a dressing of salt because the wild species of mangel is a marine plant, and thus accustomed to hign concentration of , nalt. The Rothainsted experiments on the continuous growth of mangels' show that the sodium iu nitrate of soda increases the yield, and it is probable that the sodium in ccmmon salt has a similar effect. V fr’al was carried out in 1925 in triplicate at the college farm of the University College of North Wales, Bangor, t«> determine the effect of salt on n.angels when applied with Kainit, and without h'aiuit and whether a dressing of lOc-.vt was superior to one of scwt to trie acre. In this trial the salt increased the yield by an average of over six tons to the acre, or nearly *.M per cent., when u* ed without Kainit. When used with sowt of Kainit to the acre there was practically no increase in yield. In an adjoining trial Kainit proved far superior ’ o sulphate of potash as a manure for mangels, and this must have been due to the presence of salt or similar suiistarccs in the Kainit. Experiments have shown that when about scwt of Kainit is given to mangels an additional dressing of salt is not likely tc give a return. Salt Is sometimes recommended for grassland, either for helping to eradicate certain weeds, controlling certain I parasites affecting fa*n animals, or for; inducing animals to graze rough, foggy Pastures more closely and thus improve the quality of the herbage. A dressing i of scwt to Gcwt to he acre lias been | recommended for this purpose. A j dressing of salt was also recommended | for controlling Cuke disease by destroying snals, which act ns intermediate hosts. If applied in sufficient quantity to destroy the snails it also burns the Pasture. It is now known that copper sulphate provides a much cheaper and more efficient mean- for destroying snails, responsible for this disease, and : salt can be disregaided for this purpose. As a resul; of live vears* experimental "prk at 18 centres under the Agricul- . turaj^rDepartment at Read.tig. the con-j elusion was readied that there is no evi- ; dence that salt improves pasture land. Hooding b> sea water causes severe damage to land, especially to arable hind, The injury i* uot due to the

amount of sodium chloride remaining in the soil, but is attributed to its effect upon the tilth, the soil being impervious when wet and becoming leathery when drying commen cd. Gedroiz found that soil which had an original clay content of 89.9 per cent had. after treating with sodium chloride and washing, an apparent clay content of 59.8 per cent. Also, by treating a sample of soil with sodium chloride and repeating the treatment, a “sodium clay’* was finally obtained which wa** of a most marked hydrophilic character, gelatinous, bulky, and showed little tendency to flocculate. Tile harmful effect of sea water, which contains approximately 2.7 per cent, sodium chloride, is /due to the effect of tne chloride on the soil texture. It is probable that heavy dressings of salt have a similar harmful effect on soil texture. Salt for Animals. A certain amount of salt is necessary for the health of all animals. It is an essential constituent of saliva, gastric and other j-uieci, and also the source of free hydrochloric acid in the gastric juice. It helps digestion by assisting in the passage of certain substances through the walls of the stomach and intestines, and it is necessary for dissolving the proteins; it is also a necessary constituent' of blood, lymph, etc. A cow provided with an insufficient supply of salt, over a long period has been described as developing a strong craving for it, gradually los'iig vitality, becoming rough-haired, thin in the flesh, and finally suffering a complete breakdown. At the lowa Station trials the salt consumption was found to vary according to the components of the ration, ami the opinion was expressed that salt consumption probably increases as larger amounts of fibre and protein are consumed. In many parts of the United States an addition of salt to the ration of farm stock appears to be necessary for normal production of milk and meat, and for growth. It is the exception rather than the rule to feed salt to stock in Britain. Itcccnt researches on the mineral requirements of cattle indicate a very low' requirement for sodium and chlorine. A ration containing a total amount of sodium equivalent to only one-eighth of an ounce of common salt, and chlorine equivalent to only one-fifth of an ounce of salt, was fed to two heifers for a period of 18 months. Both were in excellent condition at the end of that period, and had made growth equal to those receiving a similar ration with a daily allowance of about loa: of salt. In Britain*; where no part is very distant from the sea. it is probable that salt is carried from the sea by the wind to most districts. Goitre in the human race and in cattle is prevalent üblv in those countries situated at great distances .from the sea, and this is believed to be due to the plant foods being lower in iodine (which is present in sea water) than in those grown near the coast. It is probable that in districts situated at great distances from the sea the food plants, of the animals may be lacking in salt, and that this mineral should be added to the ration. _ I During summer salt may be provided in the form of licks nlaced in the field ar in the byre in the case of milch cows. During winter the salt may be added to the meal or chaff mixture, or may be distributed by means of the haystack. The use of salt when stacking hay saves time and trouble, and improves both good and bad hay. A few pounds of salt scattered over each load of hay in the stack not __ only helps to flavour the hay hut minimises mouldincss. The Solages method of ; fodder nreservation used on the Continent is based on the use of salt in tiie stack- The hay cron is left unturned in the swath until three-quarters [irv, when it Is carted and stacked; •nnunon salt at the rate of 11b to 501 b of fodder is added when stacking. The presence of salt in this quantity is to ’-revent ex'-essive heating ; and mouldiness. The advantage -'aimed for this method is the elimination of all the processes of hay-mak-ing except mowing.