WINNING NITRATES.

Otago Witness, Issue 3829, 2 August 1927, Page 7

WINNING NITRATES.

PROPOSED UTILISATION OF LAKE MANAPOURI. ESSENTIAL FERTILISER FOR FARMERS. The company to exploit the manufacture of ierro-chromium at Deep Cove in the Western Sounds of Southland also proposes to produce the fertiliser nitrate of lime and by-products by the electric arc system (says the Southland Times). Cheap and abundant power is - the ilrst essential. The company holds a Government license for » term ot 60 years oi one of the finest water powers in tho world, contiguous to ’ll ideal deep water harbour. 'Hie license provides for drawing 250,000 horse-power from Lake Manapouri by means of a tunnel, nearly six miles in length, as well as su,Cut) horse-power from waterfails adjacent to the outlet of the tunnel bi Deep Cove, at the head of hnnth Soundon the south-west coast. Lake Manapouri is- fcOJlt above sea level. it lias an area of 56 square miles m addition to 131 square miles of Lake he Anau which discharges through Manapouri, and the com bined annual outflow averages over 20,(X)0 cub.c feet per second. 11 further power was required, a dam three miles below the outlet of Lake Manapouri would enable the whole of the ■ discharge to be utilised, providing a gross continuous power approximating I,\aW,Cvo h.p. The cost of the tunnel is estimated at £1,140,060, to provide lor 125,000 h.p. Ihe cast of the hydro-elect lie machinery and buildings would amount to £682,01X1. Owing to natural advantages, such as cheapness in harnessing the power, an unlimited supply of limestone m the foun of marbie almost adjacent to the site of the works, as well as ample supplies of timber suitable for packing qases, there is probably no other position m the world so advantageously situated for the production of nitrate of lune. The only raw materials required are air, water, and limestone, or marble, together with power. Although the arc piocess absorbs a great deal of power it involves only a minimum of labour. All the labour required is in procur.ng the limestone and in packing the finished article. Apart from the Australian and outside world demand for nitrates there will soon be a considerable Dominion demand for topdressing worn out pastures in connection with dairy farming and the sheep industry. Recent experiments in Germany and elsewhere have demonstrated the great advantage to be gained by top-dressing grass lands with nitrates. It should be noted that New Zealand is the largest exporter ot dairy produce of any country in the world, and that some millions of acres of grazing country arc steadily going back for want ot the needful fertiliser. The experience in Germany during the last decade has demonstrated the fact that sulphate of ammonia, owing to its toxic effect on the soil, does not prcauce the same results as nitrate nitiogeu. 'Hie official statistics show that the German harvests in IS2I-25 as compared with those of 19j9 13 showed a decreased yield of 19g to per cent, on the various crops, the money loss being about £4I,(XD,OK> per annum. '1 he figures come from official sources and may be accepted ascorrect, and it is an undoubted fact that this great loss in agricultural returns coincides with the virtual disuse of Chilean nitrate in Germany. The suggestion is that the disuse of nitrate and its substitution by sulphate of ammonia and cyanamide are the chief causes for the decrease in the crop yields.

No doubt recognising that nitrate nitrogen is so much superior to ammonium nitrogen the Germans arc now largely oxidizing their ammonia to form nitric acid which can be converted to nitrate of lime. In face cf the fact that it practically costs as much to produce nitrogen in the form of synthetic ammonia as it does to produce it in the form of nitric acid by means of the direct arc process with cheap and abundant power the extra cost of oxidizing the ammonia to nitric acid is very suggestive. The Germans do not possess any large and <?heap water-power and they are thus tied down to chemical synthetic processes for obtaining their nitrogen from the air. The Leuna works alone consume 4,000,000 tons of brown coal per annum in the production of synthetic ammonia.