THE 



TROPICAL AGRICULTURIST 



AND 



MAGAZINE OF THE 



CEYLON AGRICULTURAL SOCIETY. 



Vol. XXXII, COLOMBO, JUNE 15th, 1909. No. 6. 



Reviews. 



NITRO-BACTERINE AND GREEN 

 MANURING. 



Legume Bacteria. 

 By S. P. Edwards and B. Barlow. 



Bulletin No. 169 of the Ontario Depart- 

 ment of Agriculture. 



A somewhat heated controversy has 

 recently been raging in the pages of 

 gardening and scientific papers at home 

 as to the precise value of certain cultures 

 intended to encourage the growth of 

 the nitrogen-absorbing nodules upon the 

 roots of leguminous plants. As most of 

 those interested in agriculture are now 

 well aware, the majority of plants of 

 the pea and bean family, which includes 

 such well known local representatives 

 as Crotalaria, Albizzia and Dadap, pos- 

 sesses the singular pcwer of absorbing 

 and fixing the free nitrogen of the air and 

 making use of it as food. This power 

 depends upon the presence, within cer- 

 tain lumps or nodules borne upon the 

 roots of the plants, of particular forms 

 of minute bacteria, which are gifted 

 with the exceptional faculty of accumu- 

 lating nitrogen. Within the last few 

 years it has been found possible to iso- 

 late these bacteria from the leguminous 

 plants which constitute their natural 

 habitat, and to induce them to grow and 

 multiply in artificial surroundings and 

 upon artificial food. 



So far the matter was one of purely 

 scientific interest. The question next 

 arose whether these artificial cultures 

 might not be made use of to encourage 

 the growth of the nodules upon the 

 roots of leguminous vegetables and 

 other useful plants belonging to the 

 same family. Although a series of 

 attempts had already been made to pre- 

 pare useful artificial cultures of these 

 bacteria, the problem was still in a purely 

 experimental stage when journalistic 

 eyes chanced to fall upon it, with the 

 r esult that the cultures were imme- 

 diately spread abroad, with much 

 flourish of advertisement, under the 

 name of nitro-bacterine. 



As regards the value of nitro-bacterine 

 in horticulture and agriculture, opinions 

 are still much divided. Careful compara- 

 tive experiments have been carried out 

 by several competent workers with a 

 view to determining the relative growth 

 and yield of leguminous crops treated 

 with nitro-bacterine and of similar crops 

 untreated. The results have been some- 

 what contradictory. The truth seems 

 to be that in some cases the soil 

 in which the seeds were sown was 

 already well provided with the neces- 

 sary bacteria, and that when this was 

 the case the addition of further supplies 

 made little or no difference to the growth 

 of the plants. On the other hand, in 

 soils which were poor in the particular 

 bacteria required, inoculation of tb e 

 seeds with cultures of the bacteria 



