FOOD FROM AIR

Evening Post, Volume CX, Issue 154, 29 December 1930, Page 4

FOOD FROM AIR

SAFETY FROM FAMINE

ASSURED BY NITROGEN

Thirty-two years ago Sir William Crookes reviewed the problem of feeding the ever-increasing population of the world. He concluded that only about 100 million acres of uncultivated land in the world were suitable for growing wheat, and that, if the average yield of wheat remained stationary at 13.7 bushels per acre, all the available wheat lands would be required, by 1931 (nest year, that is), and after that there would be a world shortage of wheat. The only cure for this promised shortage, he foresaw, would bo the discovery of some means of fixing atmospheric nitrogen so that the yield of wheat could rise steadily above 12.7 bushels per acre. "The fixation of nitrogen is vitai to the progress of civilised humanity," he said. "The fixation o£ nitrogen is a question of the not far distant future. Unless we can class it/. ainqngst the certainties to come, the ■great Caucasian race will cease to be the-foremost-in; the world, and will be squeezed out of existence by the races to whom wheat bread is not the staff of life.!' Science' and industry, however, have completed:, the- task that Crookes set them. They have assured .the food supply of the world for several generations to come. •To start, with, there is now a far greater area of land suitable for wheat growing than ' was anticipated by Crookes. This is due to improvements to agricultural methods, making it possible to grow wheat in dry areas; to the discovery and use of breeds of wheat which will ripen in a shorter summer, thus extending the limits of the wheatgrowing area farther north; and to the invention of improved agricultural machinery (petrol tractor, reaper, binder, and thresher), which makes 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. The yield of wheat per acre for the last 40 years has been almost 13.5 bushels per acre on a world average. It has been higher in-' some countries through the use of nitrogen fertilisers, but in others extensive cultivation has made smaller yields profitable, and these-, two factors seem just about to balance each other. NITKOGEN LONG USED. For many centuries nitrogen has been used as a fertiliser in the form of farmyard manure, and certain, rotation of crops, which kept the nitrogen in the soil, had been popular. But it was not until 1840 that the true function of nitrogen was realised, and fertilising became an art based on science. When Mr. Jorrocks gave up hunting and devoted himself to farming, in his election address he declared himself an enthusiastic supporter "of guano, nitrate o' sober, or any of them artificial compounds." This was 90 years ago nearly, and since that time the agri' cultural chomist has more and more come to realise the supreme importance of nitrogen in fertilisers for the soil. It is reckoned by Dr.'B. E. Slade that in 102S the value of nitrogen used in fertilising throughout the world was for that year £83,000,000. The development of the nitrogen fixation industry, he points out, has lowered the price of nitrogen fertilisers, so that wo can expect the needs of the increasing populations of the world to be met first,by more intensive fertilisation of land close to the markets for food, rather than by extension of the cultivated area. : Less capital is required to build a nitrogen factory than to bring new ground under cultivation. The world's consumption of nitrogen in 192S was nearly two million tons, three-quarters of which amount was consumed as fertilisers. About a million tons were produced by synthesis, needing five arid a half million tons of coal. This quantity of coal is-almost negligible when compared with the 1500 million tons mined every year. The rest of the nitrogen was produced by by-product coke ovens or tis nitrate of soda from Chile. THE NITEOGENOUS CYCLE. When we obtain increased yields of' crops with artificial nitrogen fertilisers we are making use of the storcd-up energy of the sun in past ages. Is it inexhaustible? Of the world's nitrogen cycle little is known. How much atmospheric nitrogen is combined by electrical discharges? How much by bacteria? How much by synthetic ammonia processes? How much humus changes to give nitrate? How much nitrate is washed away, and how much goes into the crop? What happens to that going into the crop, and how much of it forms humus? What happens to the dissolved nitrogen going down the rivera into the sea, and how much comes back to the land in the form of fish? Questions are endless, and answers scarce. There is no doubt that in the past, nitrogen was stored up in coal and in natural nitrate, and this is being liberated now. It is, however, a mere drop.in the ocean of nitrogen, and wo do not know whether nitrogen is being stored up anywhere at the present time. As to the nitrogen in the air we' do not know whether we are gaining or losing it. . All that does seem certain is that the world's food supply, owing to the fixation of nitrogen by the chemist, is assured for a very long time to come.