THE NITRIFICATION OF PHOSPHORUS NITRIDE 1 
By F. E. Allison 
Soil Biochemist , Fixed Nitrogen Research Laboratory , United States Department of 
Agriculture 
Phosphorus nitride has recently received some attention as a possible fertilizer 
product from the fixation of atmospheric nitrogen. A survey of the literature 
furnished no direct information as to the fertilizer value of this material. As a 
result of vegetation experiments, Stutzer 2 found that silicon nitride and oth^r 
nitrides were of little or no value as fertilizers. The article does not state whether 
phosphorus nitride was included in this work. In order to secure definite infor¬ 
mation on phosphorus nitride, the experiment reported below was made. 
This work was based upon the well-known fact that materials which do not 
nitrify readily do not serve as satisfactory nitrogenous fertilizers, although in 
unusual cases it is possible that such materials may have some plant food value. 
The phosphorus nitride used in this study was prepared by the action of 
ammonia on phosphorus pentasulfide and contained 40.03 per cent nitrogen. 
The purity of the sample on the basis of the formula P 3 N 5 was, therefore, 93.3 
per cent. It was shown that the sample contained an excess of phosphorus 
and it is probable that this element accounts for the greater part of the remain- 
ng 6.7 per cent. It was probably present largely as free phosphorus, but some 
compounds of the type PNS and PNO may have been present also. 
The experiment was made with a Susquehanna loam soil, using 100-gm. 
samples in 300-cc. beakers. In order to provide optimum conditions for nitrifi¬ 
cation, 0.5-gm. calcium carbonate was added to each soil sample. The phos¬ 
phorus nitride and the ammonium sulphate used for comparison, as well as the 
calcium carbonate, were thoroughly mixed with the dry soil and 21 per cent 
distilled water added. The soil samples were maintained at room temperature 
during the course of the experiment and any water lost by evaporation was re¬ 
stored frequently. At intervals, nitrate determinations were made on a group of 
samples, using the phenoldisulphonic acid method. These results are given in 
Table I. 
1 Received for publication Apr. 28, 1924—issued November, 1924. 
1 Stutzer, A. ueber nitride in ihren wirkungen auf pflanzen. (Abstract) Chem. Ztg. 34: 
1015. 1910. 
Journal of Agricultural Research, 
Washington, D. C. 
(1117) 
Vol. XXVIII, No. 11 
June 14, 1924 
Key No. R-2 
