208 EXPERIMENT STATION RECORD. 



now that the Leguminosa? are able, by means of root tubercles and 

 probably through the microorganisms contained in them, to convert 

 the atmospheric nitrogen into combined forms and thereby to enrich 

 the soil in the nitrogenous compounds so useful in plant nutrition. 

 Hence the Leguminosre are rightly called the nitrogen gatherers among 

 cultivated plants, and are widely cultivated both as a crop to be har- 

 vested and as a green manure, either as the principal crop or as a catch 

 crop. 



There are many questions in connection with these nitrogen gatherers 

 which are not yet settled. It remains to be studied what leguminous 

 plants are the most active nitrogen gatherers in" the different soils, and 

 under what conditions this assimilation is most active. The question of 

 inoculation is an important one in this connection. It was first used 

 practically by Salfeld, and was worked out scientifically by ISTobbe. 

 The latter found that the microorganisms in root tubercles could be 

 grown artifically, and that they could be transplanted to the different 

 leguminous plants when the latter were grown in soils containing no 

 microorganisms or an insufficient number. Nobbe calls the pure cul- 

 tures prepared by him Nitragin. He proposes by introducing the pure 

 culture into the soil near the germinating plant to stimulate the plant 

 to an active tubercle formation and consequent assimilation of nitrogen. 

 His experiments show that under certain conditions this actually takes 

 place, but the application of this in practice has not been tested to any 

 considerable extent. It is for the experiment stations to study this 

 matter thoroughly, and they are already extensively engaged with it. 



Such investigations as these are concerned with the important ques- 

 tion of a cheap supply of nitrogen for cultivated plants. This question 

 is for Europe at present a most important one, since all old soils, as 

 explained above, are very deficient in nitrogen and require for their 

 cultivation large applications of expensive nitrogenous fertilizers — 

 nitrates, ammonia salts, etc. 



Of equal importance in this connection is the conservation of the 

 nitrogen in barnyard manure. Since in Germany stall feeding is the 

 rule and pasturage the exception, the barnyard manure is naturally of 

 unusual importance and is quite indispensable, both on account of its 

 mechanical and chemical action and especially because it provides the 

 soil with nitrogen. 



Recent investigations have demonstrated that with the present 

 method of preserving and handling barnyard manure, there are very 

 large losses of nitrogen, which may be estimated at about 25 kg. annu- 

 ally per head of live stock. The tremendous loss which this represents 

 in the aggregate may be realized from the fact that there are in Ger- 

 many about 20 million head of live stock (large animals), which means a 

 total loss of 500 million kg. (550,000 tons) of nitrogen each year. If 

 only a small part of this loss could be prevented, it would be a great 

 addition to the national wealth and the experiment stations are in the 

 best position to accomplish this desirable result. Their experiments 



