EVENING DISCOURSE. 



THE NITROGEN INDUSTRY AND 

 OUR FOOD SUPPLY. 



BY 



Dr. Pv. E. SLADE. 



Thirty-two years ago Sir William Crookes, in his presidential address to this 

 Association, reviewed the problem of feeding the ever-increasing population of the 

 world, and he devoted particular attention to the supply of wheat, which is the staple 

 food of the white races. He concluded that : — 



(1) Only about one hundred million acres of uncultivated land in the world were 

 suitable for growing wheat. 



(2) If the average yield of wheat from the land remained stationary at 12-7 bushels 

 per acre, all the available wheat lands would be required by 1931, and after this there 

 would be a world shortage of wheat. 



(3) Some means of fixing atmospheric nitrogen must be found by the chemist so 

 that the yield of wheat over the whole world could steadily rise from 12-7 bushels 

 per acre to provide for the bread-eaters. 



The conclusion that only one hundred million acres of uncultivated land were fit 

 for growing wheat was based on a very careful estimate, and I do not think that 

 any better estimate could have been made at the time. 



Actually the world has now an area producing wheat much in excess of that 

 predicted by Crookes. 



The excess area suitable for wheat is due to : — 



(a) Improvement in agricultural methods making it possible to grow wheat in 

 dry areas. 



(6) The discovery and use of breeds of wheat which will ripen in a shorter summer, 

 thus pushing the wheat-growing area further north. 



(c) The invention of improved agricultural machinery — especially the petrol 

 tractor and the reaper, binder and thresher, which have made it possible for large 

 areas to be brought under cultivation with the minimum of man power, and therefore 

 with the minimum of population on the land. 



Dr. Slade then dealt with the effect of the development of the nitrogen industry 

 on agriculture. 



For many centuries he said nitrogen was used as a fertiliser in the form of farmyard 

 manure, and certain rotations of crops, which kept up the nitrogen in the soil, had 

 been popular ; but it was not until 1840, when Liebig first pointed out the true 

 function of nitrogen, potash and phosphorus, that fertilising became an art based on 

 science. Liebig's work became widely known in a very short time. If you read the 

 novels of Surtees you may remember that, when Mr. Jorrocks gave up hunting and 

 devoted himself to farming, we find him toasting nitrate of soda, and in his election 

 address to the electors of Hillingdon he declares himself an enthusiastic supporter 

 of ' guano, nitrate o' sober or anv of them artificial compounds.' This was written 

 in 1844. 



A little later Lawes and Gilbert started their experiments at Rothamsted, which 

 definitely proved the part taken by nitrogen in agriculture. 



From 1840 the use of nitrogen in the form of Chili nitrate steadily increased, and 

 about 1880 sulphate of ammonia became available from bye-product coke-ovens, 

 and by 1903 the world consumption of these two fertilisers had increased to 

 1,975,000 tons, equivalent to 351,000 tons of nitrogen. 



In 1905 calcium cyanamide was manufactured on a commercial scale for use as 

 a fertiliser, and in the same year the arc process for combining the oxygen and uitrogen 



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