Apr. 5,1924 
Studies with Cyanamid 
41 
soil in 200 or 300 cc. beakers, to which were added the various materials being 
studied. The soil used for all of the experiments was a Susquehanna loam, well 
supplied with organic matter and quite productive. It had been in constant 
eultivation for about 15 years. As shown by the experimental results, it con¬ 
tained a sufficient supply of basic elements to show a high nitrifying efficiency 
<even without additions of calcium carbonate. 
In preparing mixtures, usually the required amount of the dry salt or fertilizer 
was thoroughly mixed with the soil sample by means of a small aluminum shaker 
of the type commonly used in soda fountains. In a few cases the soluble salts 
were added in solution. The moisture content was brought up to the optimum 
of 21 cc. per 100 gm. of soil, except in one instance where this was made the 
variable factor. The water lost by evaporation was replaced at intervals of 
four or five days. During the incubation period the soils were maintained at room 
temperature, usually about 20° to 22° C., except where the temperature was 
made the variable factor. 
The analyses of the nitrogenous compounds used is given in Table I. The 
untreated cyanamid was used unless otherwise stated. 
ANALYTICAL METHODS 
DETERMINATION OF AMMONIA NITROGEN 
To a 25-gm. sample of soil were added 50 cc. of a solution of sodium carbonate 
and sodium chlorid (108 gm. Na 2 C0 3 and 150 gm. NaCl per liter) and about 1 cc. 
of paraffin oil. The mixture was then aerated for six hours in the apparatus 
devised by Matthews (18). The ammonia evolved was absorbed in N/20 
sulphuric acid and the excess titrated with N/20 sodium hydroxid, using methyl 
red as an indicator. 
Table I .—Total nitrogen content of materials used 
Total nitrogen (per cent) 
-Cyanamid, hydrated and oiled. 18. 32 
Cyanamid, untreated_20. 61 
Urea_46. 44 
Ammonium sulphate_20. 90 
Dicyanodiamid_66. 31 
Total nitrogen (per cent) 
Guaaiylurea sulphate_ 34 92 
Guanidin nitrate_ 45. 44 
Guanidin carbonate_46. 62 
Nitro guanidin_53. 84 
Biguanid nitrate_51. 00 
Table II .—Determination of ammonia by the aeration method 
Nitrogen recovered as ammonia 
Material 
Mgm. 
N 
added 
1.5 hours 
3 hours 
5 hours 
6 hours 
NHj 
mgm. 
N 
Aver¬ 
age 
NHs 
mgm. 
N 
Aver¬ 
age 
NHs 
mgm. 
N 
Aver¬ 
age 
NH 3 
mgm. 
N 
Aver¬ 
age 
Blank_ 
0.00 
/ .00 
1 .00 
/ 10.40 
\ 10.40 
/ 10.40 
\ 10.40 
2. 54 
0.04 
.19 
.17 
10.37 
10.40 
9.64 
9.89 
0.04 
.19 
.21 
10.38 
10.38 
10.27 
10.22 
.005 
0.19 
.18 
oOU.. 
Ammonium sulphate from 
solution. _ _ _ 
0.18‘ 
0.18 
0.20 
9.07 
9.73 
9.40 
10.38 
10.38 
Ammonium sulphate from 
soil__ 
10.21 
10.17 
9.76 
10.19 
10.24 
Dicyanodiamid.. _ 
88285—24f——4 
