DRY FARMING CONGRESS. 



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improve conditions in the field, that we are in a fair way to handle and 

 consider conditions which, were we in the field, and able to consider 

 conditions in the field alone, might seem unintelligible. 



I have used advisedly the words fertility in regard to a certain crop,, 

 for it is necessary to consider the fertiliy of a field as entirely relative. 

 A field may be highly productive in respect to a certain crop, such as 

 clover, but have a very low productivity for another crop, such as pota- 

 toes. In other words, the fertility of this field would be high with re- 

 spect to clover and low with respect to potatoes. There is, therefore, a 

 third possibility open to the soil bacteriologist; it is possible, even proba- 

 ble, that the conditions of optimum fertility for any crop is paralleled Dy a 

 certain definite balance among the types of bacteria in the soil. To be 

 able to recognize these different associations would make it possible for 

 a man in the laboratory after a short laboratory examination and test 

 to tell exactly what could be grown to the best advantage and what crops 

 could not succeed, or to determine what method of cultivation must be 

 used successfully to produce a given crop. This must necessarily be done 

 in co-operation with the agronomist, provided it can be done at all, as 

 it may sound visionary. We have found a curious parallel, however, it 

 the sensitiveness of the nodule-forming bacteria of any species of legumes 

 and the legume itself. For instance, in fields where clover would grow 

 but poorly even after it had been inoculated, we have found that the 

 extract of the soil moisture of that soil was injurious to the bacteria of 

 the red clover, and conversely, in soil where red clover grew very well 2fter 

 it had been inoculated in that soil solution, the bacteria of the soil 

 would grow very well. In this way, in a great many instances, we have 

 been able to foretell results and to predict failures, and in a few instances 

 have been able to outline methods of soil handling to make a crop a 

 success. 



This will give you some idea of that branch of science which has 

 most recently come to the aid of the agronomist. The field is a big one, 

 and the problems are very complex. Our progress, therefore, will prob- 

 ably be slow and tedious but I think it will be sure. To briefly recapitu- 

 late, there are certain hypotheses I wish to impress upon you. 



1. Soils cannot be productive unless they support a well-balanced 

 bacteria flora. 



2. The proper- balance of the bacterial flora of a once fertile field 

 may be destroyed and the productivity of the field destroyed until the 

 normal balance is re-established. 



3. A field may never be properly fertile, due to the lack of a certain 

 type of bacteria, until this special type is introduced into the soil. 



Now I am not urging that every farmer should become a bacteriolo- 

 gist. This is merely a question of finding out more or different condi- 

 tions. What we are after is an explanation of why some of these things 

 happen that now seem unexplainable. After we find why they happen, 

 whether bacteriologically or for any other reason, on a great number of 

 different kinds of soils, then we will ^probably be able to formulate a 



