14 REPORT— 1898. 



I have said that starvation may be averted through the laboratory. 

 Before we are in the grip of actual dearth the Clieniist will step in and 

 postpone the day of famine to so distant a period that we, and our sons 

 and grandsons, may legitimately live without undue solicitude for the 

 future. 



It is now recognised that all crops require what is called a 'dominant' 

 manure. Some need nitrogen, some potash, others phosphates. Wheat 

 pre-eminently demands nitrogen, fixed in the form of ammonia or nitric 

 acid. All other necessary constituents exist in the soil ; but nitrogen is 

 mainly of atmospheric origin, and is rendered ' fixed ' by a slow and 

 precarious process which requires a combination of rare meteorological 

 and geographical conditions to enable it to advance at a sufficiently rapid 

 rate to become of commercial importance. 



There are several sources of available nitrogen. The distillation of 

 coal in the process of gas-making yields a certain amount of its nitrogen 

 in the form of ammonia ; and this product, as sulphate of ammonia, is a 

 substance of considerable commercial value to gas companies. But the 

 quantity produced is comparatively small ; all Europe does not yield more 

 than 400,000 annual tons, and, in view of the unlimited nitrogen required 

 to substantially increase the world's wheat crop, this slight amount of 

 coal ammonia is not of much significance. For a long time guano has 

 been one of the most important sources of nitrogenous manures, but 

 guano deposits are so near exhaustion that they may be dismissed from 

 consideration. 



Much lias been said of late years, and many hopes raised by the 

 discovery of Hellriegel and Wilfarth, that leguminous plants bear on 

 their roots nodosities abounding in bacteria endowed with the propertj- 

 of fixing atmospheric nitrogen; and it is proposed that the necessary 

 amount of nitrogen demanded by grain crops should be supplied to the 

 soil by cropping it with clover and ploughing in the plant when its 

 nitrogen assimilisation is complete. But it is questionable whether such 

 a mode of procedui'e will lead to the lucrative stimulation of crops. It 

 must be admitted that practice has long been ahead of science, and 

 for ages farmers have valued and cultivated leguminous crops. The four- 

 course rotation is turnips, barley, clover, wheat — a sequence popular more 

 than two thousand years ago. On the Continent, in certain localities, 

 there has been some extension of microbe cultivation ; at home we have 

 not reached even the experimental stage. Our present knowledge leads 

 to the conclusion that the much more frequent growth of clover on the 

 same land, even with successful microbe-seeding and proper mineral 

 supplies, would be attended with uncertainty and difficulties. The land 

 soon becomes what is called ' clover sick ' and turns barren. 



There is still another and invaluable source of fixed nitrogen. I mean 

 the treasure locked up in the sewage and drainage of our towns. 

 Individually the amount so lost is trifling, but multiply the loss by the 



