FKRTILITY OF LAND NOT DUE TO ITS XITROGEX. 305 



Avliicli liad been removed in the harvest was again 

 supplied by it to the field. Accordingly, the unequal 

 fertility of land must be due to the unequal amounts of 

 nitrogen contained in it ; and it would follow that the soil 

 richer ui nitrogen must be more fruitful than one which 

 contained less of this element. 



This theory, too, came to a pitiful end ; since that 

 wliich was not true for manures could not possibly hold 

 good for land. 



Every one who is acquainted with chemical analysis 

 knows that amont? the constituents of the soil none can 

 be approximately determined vnth. greater accuracy than 

 nitrogen. ' In an exliausted soil at Weihenstephan and 

 Bogenhausen, nitrogen was determined by the usual 

 method, and calculated to a depth of 10 inches. 



17ie field contained, per hectare, 



Nitrogen 



On botli fields summer barley was cultivated in 1857, 

 and the following returns were obtained, per hectare : — 



1528 41S4 



Thus, the field at Weilienstephan, containing about the 

 same amount of nitrogen, yielded almost four times as 

 much com, and more than twice as much straw, as the 

 field at Bogenhausen. 



In 1858, these experiments were repeated at Weilien- 

 stephan with winter wheat, and at Schleissheim witli 

 whiter lye ; tlie result was : — 

 X 



