300 



PRINCIPLES OF AGRICULTURAL CHEMISTRY 



table gives some determinations made on some ordinary nitro- 

 genous materials : 



COMPARATIVE AVAILABILITY OF NITROGEN FERTILIZERS. 



Comparative Availability. The availability of nitrogenous fer- 

 tilizers for different series of experiments made by the same in- 

 vestigator exhibit considerable differences. Some workers have 

 studied only the effect upon the first one or two crops, while 

 others take into consideration the effect on several succeeding 

 crops. The results of the Connecticut Station 1 given in the table, 

 were secured in three series of experiments with (i) corn, (2) 

 oats and corn, and (3) corn, in 10 pounds artificial soil composed 

 of coal ashes and 3 per cent, moss, the root and fertilizer residues 

 remaining in the soil from year to year. A fourth series, with 



1 Connecticut State Station Report, 1897, p. 257. 



