COMMERCIAL FERTILIZERS 497 



DOUBTFUL 

 Trimethylamine 



,,/XH . NH 

 para-H-Urazme CO^V-TT 



Hexamethylenetetramine 



NOT ASSIMILATED 



Ethyl nitrate Hydroxylamine hydrochloride 



Propionitrile Methyl carbonate 



Toxic 

 Tetranitromethane 



This list comprises only those substances that have been 

 used in experiments with peas. Many other substances 

 remain to be tested, and those already tested may act 

 differently with other plants. 



One of the organic compounds isolated from soils by 

 Shorey, 1 called creatinine, has been shown by Skinner 2 

 to be used directly by plants as a source of nitrogen, 

 and to have produced a better growth of wheat seedlings 

 than did an equivalent quantity of nitrogen in the form 

 of sodium nitrate. Histidine, arginine, and creatine 

 have also been found in soils and shown to be a direct 

 source of nitrogen for wheat seedlings (par. 92) . 



These and numerous other investigations of this subject 

 show that amine as well as amide nitrogen is assimilated 

 by at least some agricultural plants, but to w r hat extent 

 most of these compounds may successfully replace the 



1 Shorey, E. C. I. The Isolation of Creatinine from Soils. 

 U. S. D. A., Bur. Soils, Bui. 83, pp. 11-22. 1911. 



2 Skinner, J. J. III. Effects of Creatinine on Plant Growth 

 U. S. D. A., Bur. Soils, Bui. 83, pp. 33-44. 1911. 



2K 



