438 



EVENING DISCOURSE. 



The population of the world increased by 10,000,000 each year from 1913 to 1928. 

 If we had to feed this increase of population by increased nitrogen fertilisation we 

 should have to build each year a works about one and a half times as big as BUUngham. 

 This works would fix 300,000 tons of nitrogen per year, and would cost upwards of 

 £30,000,000. In order to run the works we should require 1.6 million tons of coal per 

 year. If we built a works of this size every year for a hundred years we should then 

 be consuming 160,000,000 tons of coal a year for nitrogen fixation, or only 10 per cent, 

 of the coal which is being used in the world to-day. At least two-thirds of the coal 

 consumed in the fixation of nitrogen is used for power production, so we could reduce 

 the coal required to one-third the value mentioned if other sources of power were 

 available. 



There are still large areas of the world suitable for cultivation, and many of us 

 saw such areas last year in South Africa and Central Africa. It is therefore improbable 

 that all the food requirements for the growing population of the world will have to be 

 supplied exclusively from nitrogenous fertilisers for some time to come. 



Even if some generations hence such a time does come I feel assured we can look 

 with confidence to our agriculturists, our chemists and our engineers being capable of 

 finding a solution to the problem of supplying food for the growing population. 

 Perhaps before long the present tendency of the birth rate to decrease with a higher 

 standard of living will have spread to all nationalities and peoples, and the problem 

 of over-population will never occur. 



The Distbibution of Nitbogen Febtiliser. 



Let us now investigate the use which the world makes of the nitrogenous fertilisers 

 which are now available. I have already mentioned that of the 1,843,000 tons of 

 nitrogen consumed in 1928, 1,658,000 tons or 90 per cent, was used in agriculture. 



In Table III are shown the quantities of nitrogen consumed in the different countries, 

 during the year 1928. 



Table III. 



I wish that I could present to you a yearly flow sheet of the world's nitrogen cycle. 

 How much atmospheric nitrogen is combined by electric discharges ? How much by 

 bacteria ? How much by our sjmthetic 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 



