Bacteria (iiid th.e Nitrogen, Problem. 515 



agx), for unless decay takes place and the decomposed elements are 

 rearranged into definite nitrogenous salts no plant is able to use them. 

 Thus it will be seen that certain bacteria in the soil play as im- 

 portant a ])art in the food supply of the earth as do the animals and 

 larger plants upon which we think we are so dependent. 



It is hardly necessary to refer to the vast waste of nitrogenous 



matei-ial that is involved in modern sewerage methods. Millions of 



dollars' worth of nitrogen which would naturally return to the soil 



under the action of nitrifying bacteria is every year carried oft' in 



various waterways and ultimately reaches the ocean, where, of course, 



it is of no benefit to man. More than fifty years ago Liebig said on 



this subject : — 



Nothing will more certainly consummate the ruin of England than the scarcity of 

 fertilizers. It means the scarcity of food. It is impossible that such a sinful violation 

 of the divine laws of nature should forever remain unpunished, and the time will pro- 

 bably come for England, sooner than for any other country, when with all of her 

 wealth in gold, iron, and coal she will be unable to buy the one-thousandth part of the 

 food which she has during hundreds of years thrown recklessly away. 



A third great source of nitrogen loss is through the action of a 

 group of bacteria which have the power of breaking down nitrates, 

 depriving them of oxygen, and reducing them to ammonia or nitrogen 

 gas, when they are, of course, unavailable for plant food. This pro- 

 cess of denitrification, while very useful in the septic tank, which is 

 the most sanitary method of sewage disposal, is the source of con- 

 siderable loss to the farmer, and manures may often be rendered 

 pi'actically worthless hx the action of these bacteria. 



Other means by which nitrogen is lost so far as plant foods are 

 concerned, are the washing out of nitrogen salts from the soil and 

 the burning of explosives which are largely composed of some nitric 

 salt that would be directly valuable to the vegetable kingdom. Tlie 

 action of nitrate of soda, or saltpeter, has been studied experimentally, 

 and it is known that up to a certain maximum about 23 pounds of 

 nitrate of soda will yield an increase of 1 bushel of wheat per acre. 

 Thus, when hundreds of thousands of tons of ex])losives are used in 

 waging war, every battle liberating nitrogen which, if applied to the 

 soil, would increase the yield of wheat by thousands of bushels, the 

 actual cost of war should l)e estimated at considerably more than is 

 usually calculated ; and if there is soon to l)e a nitrogen famine, war 

 becomes more serious than ever before. 



With all of these destructive forces at work and nitrogen being- 

 liberated on every hand, it is no wonder that thinking men have 

 l)ecome alarmed at the prospect, and have endeavoured in every way 

 possible to discover some means of increasing the world's supply of 

 this most necessary element. 



How Nitrogen is Gained. 



The most valuable compound containing sufficient fixed nitrogen 

 to be used in any quantity as a nitrogenous fertilizer is the nitrate of 



