1S6 



DRY FARMING CONGRESS. 



to be the only explanation for this great difference in fertility. By subse- 

 quent re-inoculation of the second half of the field with soil from the 

 old field again, the second half was made a productive field. 



Now, from what Dr. Widtsoe told me the other day, I think you 

 have some of the conditions of that sort in some of the lines here. Gen- 

 erally^ speaking, however, I don't think that' the introduction of special 

 bacteria is the point to strive for, as we have decided from a few ex- 

 periments to strive mainly for the best conditions where the desirable bac- 

 teria are present. In most soils the bacteria that you w^ant are there, 

 if you give them the proper show. 



I have spoken of the nodule-forming bacteria. I just want, b^ way 

 of parenthesis — I am not going to discuss that here tonight — that is a 

 subject very, distinct from soil bacteria proper — but I want to say that 

 if any of you are interested in that there is a little bulletin issued by the 

 Department recently I think will cover all of the questions you may want 

 to ask about that, giving some plans that people have used in inocula- 

 tion of the legumes. Inoculation is not the panacea for the troubles of 

 growing legumes; it is merely one of the elements in growing them. 



These examples, I think, will show you the necessity for keeping bac- 

 teria of a desirable type in soils, to show you just what the bacteriologist 

 hopes to find out, what he may be able to do for farmers in the dry land 

 region and in other regions. 



I think I will confine myself to a little thing I have written out. 

 If I keep talking as long as I wish to I don't know when I will be able 

 to stop talking to you. 



The soil bacteriologist must learn to recognize the unfertile condi- 

 tions caused by undesirable bacterial growth, such as is represented by 

 the portions of soil in which red clover was grown. You may have seen 

 similar results in fields manured too heavily. The bacteriologist must 

 point out what changes must be brought about to re-establish the normal 

 bacteriological flora. The manner of making these changes can then be 

 investigated in co-operation with the chemist, physicist, or agronomist. 

 For his second duty the soil bacteriologist must determine if certain types 

 of bacteria w^hich could be of benefit in the soil are lacking, and where 

 this is the case he must discover how the desired bacteria may be intro- 

 duced. In the example quoted a moment ago the introduction of desirable 

 bacteria was brought about by bringing in soil from a productive field. 

 This, of course, is subject to the same mechanical difficulties and dangers 

 attendant upon the inoculation of legumes by the use of old soil, and, 

 of course, it would be much more convenient, as well as much safer, to 

 depend upon the use of pure cultures for these special types of soil bac- 

 teria where their introduction is necessar}^ to enhance the fertility of a 

 soil for any given crop, just as we now depend, to a large extent, at 

 least, upon the use of the pure cultures of nodual-forming bacteria to in- 

 crease the productivity of legumes. 



Here I want to interrupt myself to say wherever we can get condi- 

 tions sufficiently known so that we can scientifically, in the laboratory, 



