BKEEDING FOR NITROGEN. 43 



than now and under far wider ranges of conditions. Red clover, for 

 instance, has been improved comparatively little since it was biought 

 from P^nrope. Tt thrives well under some conditions, yet it does not 

 meet all the difiicnlties and is not profitable in some localities where 

 it should be made very useful. If it could be grown under conditions 

 where it is not now hardy, its use as a fertilizing agent would be 

 greatly extended, and if it were bred to extract still larger amounts 

 of nitrogen from the air, it would be more valuable as a fertilizer and 

 also as a food for domestic animals. Mr. W. T. Swingle i)roposes 

 that the nitrogen-gathering bacteria associated with the nodules on 

 the clover roots could also be bred so as to be more actively useful; 

 and since brewers have successfully bred special varieties of brewing 

 yeast for making beers of different qualities, the breeding of these 

 bacteria would seem also to be a practical undertaking. The field 

 pea, likewise, is a crop worthy of most serious effort, both that varie- 

 ties may l)e secured which will produce profitable crojis in localities 

 where it is not now successfully grown, and that the contents of its 

 seeds and its vines and leaves may have a larger percentage of this 

 most valuable element, protein. Alfalfa, cowpeas, and soy beans, for 

 like reasons, should be improved. These are the five principal nitro- 

 gen-producing plants of this country, each with its special very large 

 field of usefulness. To change each plant so that its range of suc- 

 cessful production would be enlarged 10 per cent, its jirotein content 

 increased 10 per cent, and its yield increased 10 per cent where now 

 grown, would cost only a very small fraction of the resulting increase 

 in value. Increasing the protein content in this manner would in the 

 aggregate be a very large increase of the nitrogen annually' gathered 

 from the air into the soil of the country. Since the sugar content in 

 sugar beets has been so greatlj^ increased, an increase of the protein 

 of clover from 15 per cent of the dry matter to 16.5 per cent or even 

 to 20 per cent should not be impracticable. But, important as may 

 be the increase in nitrogen, breeding so as to adapt these croj^s to 

 conditi(ms where they now partially or wholly fail, and increasing tlieir 

 general yield and other good qualities in localities where they are 

 now used, are tlie more important problems and probabh' should 

 receive the first attention. 



There is no reason why tlie nitrogen (content of a variety can not be 

 increased as well as the sugar content, the flavor, tlie hardiness, tlie 

 height, or any other measurable chai'acteristic. The Kansiis experi- 

 ment station found that ears of corn of a variety grown for thirty 

 years on the same farm varied in protein content from 9 to 13 per 

 cent, and that dilTerent varieties of corn varied al)out tln^ same. 

 Professor Hopkins, of the Illinois station, proved that corn plants with 

 grain high in percentage of nitrogen generally produced grain with 

 more nitrogen, thus proving that this quality can be impi-ovcd, and 

 he sliowed that something can be done at making the selections bv 



