514 Agricultural Journal of Victoria. 



BACTERIA AND THE NITROGEN PROBLEM. 



By Geokue T. Moore, 



Physioloyisf in Charge uf Lah oratory of Plant Physiology, 

 Bureau of Plant Industry, U.S.A. 



Introduction- 



There is probably no fact iu plant pliysiology which has been 

 more firmly established than that all plants must have nitrogen in 

 order to thrive, and that undei' normal conditions this nitrogen must 

 be obtained through the roots in some highly organised form. It is 

 not necessary to discuss this point, for practical experience 

 demonstrates its truth every time a soil is exhausted by any crop, and 

 the farmer testifies to his belief in this fact when he tries to re- 

 establish the fertility of his ground by adding some fertilizer rich in 

 nitrogenous matter. While there are certain other substances, such as 

 ])hosphoric acid, potash, iron, etc., which plants must have and can 

 only obtain through the soil, the demand for nitrogen is so much 

 greater and in one sense so much more important, that the question 

 of the available nitrogen supply in the world has come to be looked 

 upon as lying at the very foundation of agriculture and demanding 

 the most careful consideration. Since the conditions of life in the 

 civilized quarters of the globe are such as to cause a constant loss of 

 nitrogen, there have been some who have predicted what has been 

 termed a "nitrogen famine," which is to occur within the next forty 

 or fifty years, and the possibility of such a catastrophe has been very 

 graphically portrayed. On the other hand, there are investigators 

 who feel that the possibility of such a condition has been much 

 exaggerated and that the amount of nitrogen in the soil can never be 

 exhausted to such an extent as to affect the crop-producing power of 

 the earth. In order that we may be able to form a more definite 

 opinion upon the subject, it may be well to look at some of the ways 

 in which nitrogen is lost, and then see how it may be reclaimed. 



How Nitrogen is Lost. 



In the first place, the conditions of life on the ordinar}^ farm are 

 such as to cause the constant loss of this valuable element through 

 the removal of the crops taken from the soil. If every crop that 

 grew on the land could be returned to it, nature has made provision 

 for getting it back in suitable form for plant food. In the case of 

 nitrogen neither plants nor animals are able to produce this substance 

 directly in an available form. It is necessary that certain bacteria 

 take hold of plant and animal products, and by means of peculiar 

 changes produce nitrates from their fats, sugars, starches, etc. With- 

 out these bacteria everything would have come to a standstill long 



