Transactions of RHASS Volume 1940 - Page 016
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| Year | 1940 |
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| OCR Text |
20 STOCK-FEEDING UNDER WAR CONDITIONS. STOCKFEEDING UNDER WAR CONDITIONS. 21 time the solution is drawn off and retained for further use; An alternative system is to use two tanks, one for soaking the straw is then thoroughly washed with cold water, the and another for washing. A convenient arrangement is to first of the washings being retained because it contains _an appreciable amount of soda. The washed material, which contains about 20 per cent of dry matter, is ready for feeding. Coming to details, the one alternative is to carry out'the process in a single tank which may be of ungalvaniscd iron (soda attacks zinc) or concrete. Soda has no action on concrete, and the type of tank required would be easier to construct, by means of farm labour, than 6.9., a sheep dipper. The amount of soda solution required approaches one gallon for each pound of straw. Thus to treat 200 pounds of straw daily (which would provide a daily ration for about twenty feeding cattle) the tank should hold 200 gallons .w1thout risk of spilling. For convenience in handling, stirring, and draining, a long, narrow, and fairly shallow tank is best. To obtain 200 gallons’ capacity when filled to Within nine inches of the brim, the tank might be 12 ft. long, 2 ft. 6 m. wide, and 2 ft. deep. The bottom should have a slight slope from end to end, and there should be a V-shaped gutter along the bottom to assist drainage. This gutter should be covered with a small-meSh grid, or a sheet of perforated 1ron, to prevent its blocking. With the single-tank system there must be a sump of the same capacity as the tank, with preferably a hand-pump to lift the solution from the sump back into the tank. The procedure in operating the plant is as follows. Two hundred gallons of water is run into the tank and 30 lb. of caustic soda, in flake form, is dissolved in it. Two hundred pounds of chopped straw is now added, and the mixture is well stirred. On the following day (after about twenty hours) the pipe connecting to the sump is opened, and the solution is allowed to drain off. The treated straw is now sprayed with water, and the washings are allowed to run into the sump until the latter contains 200 gallons. When the sump , is full the remaining washings are allowed to run to waste. About ‘five waters’ are required to ensure that the soda will be completely removed, and the washing should not be hurried, but should be done at intervals over a period of some three hours. When washing is complete the pulp is removed in pails or feeding-boxes, and may be fed either immediately or later; it will keep fresh, if desired, for two or three days. The next batch of chopped straw is now placed in the tank. The solution in the sump is brought up to strength by adding about fifteen pounds of soda, and it is then pumped back into the tank. The process is repeated for the next day’s supply.” Once a week the whole of the stale solution is allowed to run to waste and a fresh start is made. have these placed parallel to each other, with the washing- tank at a higher level than the other, and with a sloping concrete ramp, about seven feet wide, between the two. The straw pulp, after soaking, is thrown on to the concrete ramp to drain, and is afterwards pushed into the upper tank for washing. Complete instructions for building and running such a plant have been drawn up by Imperial Chemical Industries. The soda solution is not dangerous to work with if due precautions are taken. Care must be taken to prevent the access of animals to it, as if drunk it would cause severe burns to the gullet, and might very likely be fatal. A splash of the liquor in the eye might cause blindness unless immediate treatment was given. In case of such an accident the worker should lie down and water should be poured from a jug into the eye over a period of an hour. The liquor will also cause burns on the skin unless it is thoroughly and immediately washed. The liquid freezes at a few degrees below the freezing- point of water, so that the plant should be under cover. Obviously, a plentiful supply of water is essential, for the treatment of every pound of straw requires a gallon of solution, and the proper washing of the product requires two or three gallons more. One other point is that the crude washing water will kill fish if it is allowed to run direct into streams. A soak-away should therefore be provided. As regards costs, detailed figures are not yet available, but a fairly close estimate may be made. At the time of writing (February 1940) caustic soda in suitable flake form can be bought at 13s. per cwt. On the single-tank system described above, the consumption of soda is about 190 lb. for each ton of straw treated. The cost of material would thus be 22s. per ton. To this we may add, perhaps, 5s. per ton for chopping the straw and probably less than 10s. per ton for labour; the latter figure assumes that about an hour a day would be spent in running a plant of the size that has been used as an example. A larger plant would no doubt give a lower labour cost per ton. Where water is paid for by volume, the cost of this must be added. The amount required will be six or seven thousand gallons per ton of straw treated. The capital cost of the plant is obviously small; if gravel and sand can be obtained locally and if the concrete work can be done by farm labour, the direct expense (for cement and a small hand-pump) need not exceed seven or eight pounds. At the other extreme, the cost by contract might be nearly £20. The charge for interest and depreciation would in any case be practically negligible. The total cost of the process is therefore estimated at 37s. per ton of straw. |
| Title | Transactions of RHASS Volume 1940 - Page 016 |
