33 



Nitrogenous Tankage, manufactured by the Fertilizer By-Products Co., Nor- 

 folk, Va. Two grades were furnished by the company and a composite of the two 

 was used in the experiment. The average nitrogen content was 6.215 per cent, 

 practically all of which was in water insoluble form. 



Nitrolene, manufactured by F. S. Royster Guano Co., Norfolk Va. The 

 sample was procured from the manufacturer. It contained 8.90 per cent nitrogen, 

 of which .85 per cent was in ammoniacal, and 5.38 per cent in water soluble organic 

 form. 



Omega Tankage, manufactured by the International Agricultural Corp., 

 Norfolk, Va. One sample was secured through trade channels and one furnished 

 by the company upon request; a composite of the two was used in the experiment. 

 The average content of nitrogen was 8.375 per cent, of which .22 per cent was in 

 ammoniacal, and 1.47 per cent in water soluble organic form. 



Process Tankage, manufactured by the Smith Reduction Co., Norfolk, Va. 

 This contained 7.48 per cent of nitrogen, of which 7.38 per cent was in water in- 

 soluble form. 



Outline of the Experiment. 



Each pot received 40 pounds of soil mixture (one part loam from nitrogen deficient 

 soil and two parts sifted sand) . The fertilizers were mixed with the entire amount 

 of soil in each pot, the basis of application being as follows: 14 grams fine ground 

 limestone, 5 grams each of muriate of potash and potash-magnesium sulfate, 

 lyi grams high grade sulfate of potash, 18 grams each of 16 per cent acid phosphate 

 and basic slag phosphate. The nitrogen-containing materials were applied in 

 unit quantity (sufficient to supply .42 grams of nitrogen) . 



The experiment was run in two series: one to show the availability of the total 

 nitrogen; the other to show the availability of the water insoluble nitrogen. Neces- 

 sary checks were run with double the amount of nitrogen from dried blood, the 

 standard nitrogen source; and with increased amounts of the basic fertilizer ap- 

 plication. 



By both sub-irrigation and surface application the plants were supplied with 

 water in amounts representing 50 per cent of the water holding capacity of the soil 

 until hot weather when it was increased to 60 per cent. 



Japanese millet was the crop grown. All pots had ten plants except pot No. 55 

 which had only nine. The plants were harvested on the same date, when in 

 full milk stage. 



With the exceptions noted above, the experiment was conducted according to 

 the general methods described on pages 11 and 12, Control Bulletin 25. 



The follow^ing table shows the yields of dry matter and the nitrogen recovered 

 in the above-ground parts of the plant; the nitrogen availability of each product, 

 from the standpoint of both total and water insoluble nitrogen and on the basis of 

 yield of dry matter and nitrogen recovered from dried blood being placed at 80. 

 The activity of the total and water insoluble nitrogen in each product as shown by 

 the two laboratory methods is also given. 



Series 1. — Unwashed. ^ {See footnote page si.) 



