306 MIMONIA AND NITKIC ACID. 



Nitrogen contained to the depth 0/ 10 inches^ per hectare, 



Schleissheim "Weihenstephan 



Idlogr. kilogr. 



2787 5801 



Crop. 



Com . . 115 



Straw . 282 •( 



397-6 4729 



The amount of nitrogen in the field at Schleissheim, as 

 compared with that at Weihenstephan, bears the propor- 

 tion of 1 : 2 ; whereas the crops are in the proportion of 

 1 : 14. These facts are fatal to the opinion that there 

 exists any connection between the amount of nitrogen in 

 a soil, and its powers of production ; and in truth no one 

 now entertains this behef. For since Kroker in 1846 de- 

 termined the nitrogen in 22 kinds of soil from various 

 districts, and discovered that even an unfi'uitful sand 

 contained more than a hundi-ed times, while m arable soils 

 to a depth of 10 inches there were present from 500 to 

 1000 times, more nitrogen than is necessary for a good 

 crop, similar investigations have been made in all coun- 

 tries, and Ki^oker's results have been confirmed. 



Since that period the fact has been generally admitted, 

 that the great majority of cultivated soils are far richer in 

 nitrogen than in phosphoric acid ; and that the relative 

 proportion of nitrogen present, which had been adopted 

 as the standard for calcidating the value of manure, was 

 quite inapphcable for estimating the productive power of 

 land. 



Hence, between the chemical analysis of mamu'es, and 

 that of the soil, there arose an irreconcilable contradic- 

 tion. In the chemical laboratory the effective value of a 

 manure could be accurately determined according to 

 the per centage of its nitrogen ; but when the farmer 

 had incorporated his manui-e with the soil, the determina- 



