244 Bulletin 247. 



a great wave came in from the sea and overflowed a large tract of land 

 that thereafter became sterile. Investigations by Dymond indicate that 

 the amount of salt deposited was not sufficient to cause sterility. This 

 condition was attributed in part to the killing of the earthworms. 



Of course it will be understood that should earthworms prove to be 

 an important factor in the growth of crops, as long ago pointed out by 

 Darwin, it will be primarily a matter of furnishing the best conditions 

 for their multiplication and growth. A study, therefore, of the best con- 

 ditions for the growth of earthworms may be advisable and may lead to 

 better and more rational cultural methods. 



Conclusions from alfalfa experiments. 



What are the inferences to be derived from these observations on 

 alfalfa? The reason for inoculating alfalfa is to supply it with nitrogen 

 from the air. The reason for applying lime is to make the nitrogen 

 available, although it may yet be necessary to prove whether it has a 

 direct or indirect influence. The reason for adding stable manure is to 

 supply a source of nitrogen which may readily become available. I do 

 not contend that lime and stable manure may not do other things. I 

 contend they do these things. That is sufficient for my present thesis. 



The occurrence of an excess of water-soluhle nitrogen. 



The discussion of a subject of this kind is somewhat like trying to 

 convict a man for murder on circumstantial evidence. It is only on 

 the accumulation of considerable evidence that a conclusion may be safely 

 reached. In fact, it may be well that this is not a subject that can be 

 safely electrocuted, but one in which life imprisonment only is indicated. 



I wish now to call attention to some observations of quite a different 

 character, but all apparently having some relation to the nitrogen prob- 

 lem. On the Mitchell farm there are two areas that failed to raise crops 

 in 1905. One will be called the cabbage spot because it failed to raise 

 mangel wurzels and cabbages and the other the timothy spot because it 

 failed to raise timothy. 



The history of the cabbage spot is as follows : In the spring of 1905 

 an old timothy meadow was plowed and the portion under consideration 

 was planted to mangel wurzels. On a large circular area about 90 feet 

 in diameter, the mangels died when plants were quite small. This area 

 was planted to cabbages. These cabbages lived, but at the end of the 

 season they were about the size of a man's hand while on a nearby area, 

 which three field agent experts of the Bureau of Soils declared to be 

 identical in all outward appearance, 35 tons of cabbage were raised per 

 acre. 



,iTi 



