II.] SOIL INOCULATION 37 



* 



commercially at the present time and have in some 

 cases been somewhat unscrupulously boomed as 

 dispensing with the need for nitrogenous fertilisers. 

 Undoubtedly cases may be quoted where the use of 

 these pure cultures of nodule-forming bacteria has 

 been of great service, generally on newly-reclaimed 

 soils, which have thus become for the first time capable 

 of carrying a leguminous crop. But in old cultivated 

 soils the organism is already present, and sufficient 

 evidence is not yet forthcoming to show that the new 

 introductions have had any effect ; certainly the results 

 obtained in the British Isles are almost wholly negative. 

 Doubtless the useful soil bacteria will be domesticated, 

 improved, and made more effective, just as our flocks 

 and herds have been tamed and developed, while the 

 useless ones will be stamped out as vermin ; but at the 

 present time we cannot be satisfied that any improved 

 race of bacteria introduced artificially into the soil has 

 managed to persist and get a real footing in face of the 

 competition of the enormous natural bacterial flora 

 already existing there. So the picture of the farmer 

 carrying the manure for a field in his waistcoat pocket and 

 applying it with a hypodermic syringe, is still a vision 

 of the future. 



These natural processes for the recuperation of our 

 stock of combined nitrogen have, during the last year 

 or two, been supplemented by one or two manufacturing 

 processes of great interest in themselves, which are on 

 the point of becoming factors of importance in the 

 fertiliser market. 



Speaking broadly, there are two ways of bringing 

 free nitrogen gas into combination : first, at extremely 

 high temperatures, such as are attained in the electric 

 arc or sparks, nitrogen will combine with oxygen to 

 form various oxides from which nitric acid will eventually 



