38 CONTROL SERIES No. 45 



Definition of Products Secured by Heating Calcium 

 Phosphate with Alkali Salts Containing Potash. 



These products are not potassium phosphate. They may be called non-acid 

 phosphates with potash. 



Unleached Wood Ashes. 



Unleached wood ashes are ashes that result from burning unleached wood, 

 that have had no part of their plant food removed, and that contain four per 

 cent (4%) or more of water-soluble potash (K2O). 



Nitrate of Soda (Commercial Sodium Nitrate). 



Nitrate of soda is a nitrogen salt containing not less than fifteen per cent 

 (15%) of nitrogen, chiefly as sodium nitrate. 



Kainit. 



Kainit is a potash salt containing potassium and sodium chlorides and some- 

 times sulfate of magnesia, with not less than twelve per cent (12%) of potash 

 (K2O). 



Dried Blood. 



Dried blood is the collected blood of slaughtered animals, dried and groimd 

 and containing not less than twelve per cent (12%) of nitrogen in organic form. 



Fertilizer Grade. 



The grade of a fertilizer shall represent the minimum guarantee of its plant 

 food expressed in terms of nitrogen, available phosphoric acid, and water-soluble 

 potash. 



VEGETATION POT EXPERIMENT TO DETERMINE NITROGEN 



AVAILABILITY OF PROCESSED LOW-GRADE MATERIALS, 



ACTIVATED SEWAGE AND OTHER ORGANIC FERTILIZERS. 



This is a report of results of a vegetation pot experiment and is a continuation 

 of work begun four years ago in an effort to study the actual availabiUty of the 

 nitrogen in processed low-grade fertilizing materials valued chiefly for their 

 content of organic nitrogen. The present experiment includes some materials 

 not suspected of being processed or containing nitrogen of inferior quality. 

 They were included in order to secure reliable data as to their nitrogen avail- 

 ability as compared with dried red blood, the nitrogen of which is known to have 

 a high crop producing value as well as high nitrogen activity by both of the labo- 

 ratory methods. For those materials under experiment for more than one year 

 the samples employed the previous season were not used in 1928; new samples 

 were secured which in most cases represented the products as manufactured 

 in January or February of 1928. 



Description of the Products under Experiment. 



Dried Red Blood of quality used for feeding domestic animals. This is the 

 standard and is generally recognized as a domestic source of quickly available 

 nitrogen. Analysis: total nitrogen 13.70%, ammoniacal and nitric nitrogen 

 none, water soluble nitrogen .46%, water insoluble nitrogen 13.24%, total phos- 

 phoric acid .66%. 



Dark Dried Blood, fertilizer grade, dried at a higher temperature than the 

 dried red blood, and is more hard and brittle. Received through trade channels 

 Feb. 26, 1928. Analysis: total nitrogen 14.14%, ammoniacal and nitric nitrogen 

 none, water soluble organic nitrogen .28%, water insoluble nitrogen 13.86%, 

 total phosphoric acid .51%. 



Foreign Nitrogenous Tankage, manufactured by Anglo-Continental Guano 

 Co., London, England. Sample secured through trade channels Feb. 26, 1928. 



