146 



THE AGRICULTURAL NEWS. 



May 15, 1909- 



results obtained by Messrs. Hellriegel and Wilfarth. 

 Although these have been fully established, it may be 

 added that the exact details of the whole process by 

 which the nitrogen of the latmosphere is first assimi- 

 lated by the bacteria and afterwards taken over and 

 utilized by the plant are not yet clearly understood. 



The importance of the whole question is indicated 

 by the large quantities of nitrogen which a leguminous 

 croj) is frequently enabled to withdraw from the air, 

 even in the course of a single season, through the 

 agency of the bacteria obtained in the nodules on its 

 roots. As examples, it may be mentioned that in 

 experiments carried out at the New .Jersey Experiment 

 Station, a crop of crimson clover was found to have 

 added over 200 lb. of nitrogen per acre to the land in 

 one year, while trials with velvet beans have shown 

 nitrogen gains amounting to 213 th. per acre in 

 Alabama, 172 lb. in Louisiana, and 141 tb. in Florida. 



In the light of the knowledge thus accumulated 

 on the subject, the question naturally suggested itself 

 to investigators as to whether the co-operation of 

 leguminous crops and nitrogen-gathering bacteria 

 might not be more extensively utilized in enriching 

 the soil and increasing its crop-yielding capacity. With 

 this object, therefore, a number of preparations for 

 inoculating the soil, all containing the bacteria 

 J'st'iiilomoiia.s niiUfifiihi, have, at different times been 

 placed on the market, and a good deal of experimental 

 work has been carried out in the United States. 

 iJerma'ny, Canada, and in England. The value of 

 inoculation under certain circumstances has undoubt- 

 ■edly been indicated, but, speaking generally, the results 

 have so far — for different reasons — been distinctly less 

 promising than was at one time anticipated. 



So long ago as 1>^'S7, .some inoculation trials were 

 undertaken in ( Jermany. In this case, the land under 

 experiment — reclaimed moor-land — was dressed with 

 soil from a field which had previously borne flourishing 

 legume crops. The results were successful, and 

 eminently encouraging, ajjd the example thus set was 

 speedily followed in many "(iistricts. In view of the 

 expense of carting soil over long distances, and of the 

 danger of introducing weeds or plant diseases, this 

 method was, however, soon substituted by the introduc- 

 tion of pure cultures of the nitrogen-gathering bacteria, 

 put up in a convenient form for inoculating either 

 a quantity of soil, or of the ^eed about to be sown. 



l'S9.5 by a Gernian experimentor, Xobbe. It was 

 known as ' Xitragip,' and consisted of pure cultivations 

 of the PsriidoiiKjnas organism on a gelatine medium. 

 ' Xitragin ' was e.xtensively tested both in Europe and 

 America, but the ijesults, on the whole, were not at all 

 satisfactory. This failure was generally believed to be 

 due to the unsuitable nature of the medium (gelatine) 

 on which the bacteria were grown, and when this was 

 changed a greater degree of success was attained- 

 Another scientist (Hiltner) brought forward a method 

 of cultivating tha bacteria on agar jelly, while Moore 

 introduced the still greater change of sending out the 

 bacteria contained in cotton wool, which had beei> 

 soaked in li(juid cultures and afterwards dried. This 

 preparation is added to a large bulk of water, with 

 which the seed to be inoculated is treated before 

 sowing. Moore's preparation was used in a very 

 extensive series of experiments carried out bv the 

 United States Department of Agriculture in 1904.. 

 The results were very confficcing, but, on the whole, 

 were unfavourable, although slight increases of crop- 

 were noticeable in many cases as the result of inocula- 

 tion. Probably many of the fadures noticed were due 

 to lack of skill in preparing, handling, and employing 

 the cultures. Culture preparations are still sent out 

 by the United States Department of Agriculture, buti 

 they are now put up in liquid form, enclosed in 

 hermetically sealed bottles. 



In 1907, Professor Bottomley, of London, brought 

 forward a new preparation of nitrogen-fixing bacteria 

 for inoculation purposes, to which the name of ' Nitro- 

 bacterine' was given. This was tried in numbers of 

 experiments, but its introduction into the soil appeared 

 to have little inHuence on the yields of the various 

 leguminous crops -treated. Sample cultures were ob- 

 tained by this Department and by one or two estate 

 owners for trials with various crops in the West 

 Indies (including sugar-cane, since Professor Bottomley 

 devised special preparations, which he hoped would be 

 useful not only with legumes, but with plants of other 

 orders as well). The experiments made are reported 

 upon on page I.tI of thi.s issue. It will be seen that 

 while inoculation had no influence on the return.s 

 obtained with cowpeas at Antigua, the crop ^uelds of 

 woolly pyrol showert, in the case of one estate at least, 

 considerable increase as the result of treatment. The 

 results at (Jrenada also show one or two points of 

 interest. Inoculation of sugar-cane at Antigua and 

 Piarbados had no "effect whatever. 



The first preparation pf the kind introduced on There are undoubtedly certain conditions under 



a commercial scale was placed on the market about which inoculation of the soil with]| nitrogen-fixing 



