COBALT DEFICIENCY IN SOUTHLAND

Southland Times, Issue 23816, 13 May 1939, Page 18

COBALT DEFICIENCY IN SOUTHLAND

Top-Dressing With Treated

Mixtures

RESULTS OF LATEST RESEARCH BY CAWTHRON INSTITUTE

Further study of the soil deficiency problem in Southland made by the Cawthron Institute has shown that'satisfactory results can be obtained from applications of top-dressings containing considerably smaller quantities of cobalt than were previously recommended by the institute. Investigations into the failure of stock to fatten satisfactorily in parts of Southland have been carried out by the institute over a period of several years. A deficiency of cobalt was held to be responsible and farmers were recommended to use salt licks containing cobalt, cobalt drenches and top-dressing mixtures including small quantities of cobalt. , In a news article contributed by the institute the latest progress made in the investigation is surveyed and special consideration is given to the use of cobalt in top-dressing mixtures. A statement prepared by the institute and published two years ago contained the following recommendations: (1) A lick containing 4oz cobalt chloride (or soz cobalt sulphate) to the ton of dairy salt is a very satisfactory method of preventing' the onset of the sickness. The lick can be put out any time, but certainly not later than June for next season’s lambs. The cobalt salt should be dissolved in water and sprayed on to the correct quantity of salt. During the period 1 when the ewes are on turnips or other green feed there will be no difficulty in getting them to take the salt, but later in the season, if the salt intake is lowered, it may be desirable to add a few drops of aniseed, or sprinkle oats or meatmeal on to the salt. At locations near the sea-coast less salt will be taken; in these cases the cobalt content of the lick may be increased up to four times the recommended amount.

(2) Drenching with a drench gun is a safe and effective method, but more laborious than the provision of licks. Using a modem drench gun more than 200 lambs an hour can be drenched by a competent man. Where the lambs are already sick this method is recommended because lambs unaccustomed to licks may be slow to take them and the sickness may temporarily become worse. It is recommended, therefore, in these cases that a drench be given twice a week for a few weeks and that a lick be put out when drenching begins. It must be emphasized that cobalt is not given as a worm drench, but to supply a deficiency of cobalt in the animal, and since the lamb can absorb only a small percentage of cobalt from any one dose it is desirable to supply cobalt in small regular supplements rather than in one or two big doses. DRENCH SOLUTION To make a drench solution containing the requisite amount of cobalt the following procedure is recommended: Dissolve loz of cobalt chloride in one quart of water, then take 1 fluid oz of this solution and make up to 2 quarts with water; J fluid oz of this solution would be a satisfactory dose for sheep. This doge will supply 1.64 mg. cobalt, and two doses a week would give cobalt 'approximately at the rate of J mg. a day.

(3) Farmers making hay could incorporate cobaltized salt in the hay if desired.

(4) The sickness, while apparently confined to certain localities in Southland, may easily appear on farms hitherto regarded as healthy, especially where top-dressing keeps the carrying capacity high. Much of Southland is covered by the same type of soil and farmers should watch carefully for symptoms of sickness. Since cobalt is inexpensive to use there is no reason wjiy they should not play safe and incorporate cobalt in licks which are already in use.

(5) Excellent results with lambs have been obtained this year (1937) by holding them on a pasture top-dres-sed with 101 b of cobalt chloride to the acre. While the cost of cobalt chloride prevents the extensive top-dressing of pastures at this rate of application, there is a good deal to be said for the topdressing of a small field which would serve as a hospital paddock for those lambs which show symptoms of ailment. | FURTHER EXPERIENCE In paragraphs 1 to 4, the recommendations given 1937 still stand in 1939, but in paragraph 5 the Cawthron Institute has had further experience with top-dressings and it is the purpose of this communication to summarize the results with cobaltized fertilizers obtained in the last two seasons.

Replicated plots were established in conjunction with the 101 b of cobalt chloride top-dressing mentioned above and regular monthly grass samples were taken from these plots. The analyses showed that a month after top-dressing, the cobalt plots had 30 times as much cobalt in the gress as the control while even after 18 months the cobalt plots were five times the control. Since pasture analyses in Southland and elsewhere have suggested for health in lambs a figure about twice the un-top-dressed figure is entirely satisfactory, the inference is that a much

smaller dressing than 101 b an acre of cobalt chloride will be effective. With this idea in mind, top-dress-ings have been made at the rate of 21b cobalt chloride equivalent an acre, at lib, at Jib and this season at 4lb an acre. In each case analyses of-the pasture have shown that the cobalt content has been sufficiently enhanced to bring the level to a desirable figure. Unfortunately, from this aspect, it has been difficult to get authentic cases of lamb sickness in Southland during the past two seasons, even when no cobalt Mains, so that it has not been possible to make the ultimate test whether animdls would stay healthy on Jib cobalt chloride application, although there is every expectation that they Would do so if there had been a widespread occurrence of the sickness.

On the experimental plots at Morton Mains no lambs have gone sick in the past two seasons, even when no cobalt has been given them. It is not known yet what factors govern this seasonal incidence of the sickness. SMALLER QUANTITIES From the pasture analyses it seems possible that even smaller quantities than Jib cobalt chloride equivalent an acre may be effective in raising the cobalt content to a satisfactory level, but this has still to be proved by animal tests. Since pasture took up cobalt so effectively, other fodder plants were tested to ascertain if they also weije able to absorb cobalt from the soil. Rape leaves, both the bulb and the tops of turnips and swedes have all been shown to have a higher cobalt analysis after top-dressing. These results suggest that the usual practice of putting cull lambs on to rape to fatten for the works might be improved in certain cases by using cobaltized superphosphate rather than ordinary superphosphate. The dressings of |lb cobalt chloride cannot be expected to last longer than a few months. It should be the aim of the farmer, therefore, to top-dress his lamb paddocks with cobalt in the spring so that he has a good cobalt supply throughout the spring and summer. By this means he should get the maximum cobalt to his lambs from the minimum of top-dressing. Since his object is usually to get fat lambs into the works early in the New Year, it is of no great moment to him if his grass paddocks get low in cobalt then, because the store lambs would be going on to rape, and so on, and a dressing could be given there if.it were necessary. In most of the Cawthron Institute experiments superphosuhate has been used as a carrier for the cobalt, but basic slag appears to be equally effective. MAKING COBALT SOLUBLE Originally, it was expected that a Rhodesian product containing 10 per cent, cobalt would prove the cheapest cobalt source for the manufacture of cobaltized superphosphate, and a process was devised for rendering the cobalt in this material soluble during the course of superphosphate manufacture. However, for the time being, Rhodesian slag of this quality is not procurable and cobalt monoxide has been substituted in recent experiments of the institute. No difficulty has been experienced in a works test in manufacturing a cobaltized superphosphate containing over 90 per cent of the added cobalt in a water soluble t state.

Many fertilizer vendors will find it more convenient to prepare cobaltized fertilizers by mixing the required amount of cobalt salt direct into superphosphate or other phosphatic fertilizers. Cobalt chloride and cobalt sulphate could both be used for this purpose. It must |be emphasized, however, that different cobalt salts contain different percentages of cobalt. Cobalt chloride for example contains about 25 per cent and cobalt sulphate about 20 per cent of actual cobalt.

If 51b of cobalt chloride to the ton of cobaltized superphosphate be accepted as a desirable cobalt concentration, 6|lbs of cobalt su’nhate to the ton must be used to give an equivalent cobalt concentration if the latter salt is used for preparing cobaltized fertilizers.

At present-day prices cobalt sulphate is the cheaper a unit of cobalt—a recent quotation for indent orders on bulk quantities being' at the rate of 2/3 a lb C.I.F.- sterling New Zealand main ports. LATEST RECOMMENDATION In conclusion, the points mentioned under paragraphs 1-4 at the beginning can be emphasized again. The following recommendations can be made about the use of cobalt top-dressing: — (1) Analyses have shown that cobalt salts incorporated into fertilizers such as • superphosphate and basic slag and then applied as a top-dress-ing at a rate equivalent to as low as lib cobalt chloride an acre, result in a very material increase in the cobalt content of the pasture. Although, owing to unfavourable seasons, confirmation of the successful use of this material top-dressing of cobalt in actual lamb trials has not yet been obtained, a consideration of data from other experimental work of the institute indicates that a dressing of cobalt salt at the above rate will be effective in a season when lamb sickness is prevalent. On the acre basis one cwt of a cobaltized superphosphate containing 611bs cobalt sulphate a ton should prove an effective dressing on affected pastures in Southland. (2) In order to obtain the maximum benefit from the cobalt topdressing it should be applied in the spring. (3) Cobaltized fertilizers can be used to augment the natural supply of cobalt in rape, swede and turnip crops.