The amounts of ammonia recovered from the different materials 
after two days and the relative rates of ammonincation throughout 
bear similar relations to those of the previous series. In the cases 
of casein, dried blood, and soy bean cake meal, from which the largest 
yields of ammonia were obtained in the sand cultures, still greater 
amounts accumulated in the soil. The ammonincation of cotton- 
seed meal and linseed meal was more nearly equal at each period, 
being practically the same as that which took place in sand. The 
losses by evaporation were considerably less than from the sand, due 
probably to the high absorbing power of the clay. A small amount 
of nitrification took place, but it was not proportional to ammonifica- 
tion. The data for the total ammonincation show a wide difference 
in the decomposition of the materials; 50.2 per cent of the nitrogen 
in casein was converted into ammonia, 42.4 per cent in dried blood, 
40.9 per cent in soy bean cake meal, 27.1 per cent in cottonseed 
meal, and 26 per cent in linseed meal. Thus the availability of these 
materials as measured by ammonincation varies greatly. 
Direct distillation with magnesia, especially in those instances 
where comparatively large amounts of ammonia had accumulated, 
yielded considerably more ammonia than the distillation of hydro- 
chloric-acid extracts; but, again, distillation of the latter with mag- 
nesia yielded as much ammonia as distillation with caustic soda." 
It would seem, therefore, that direct distillation with magnesia 
affords a truer measure of ammonincation in clay soils than indirect 
distillation of hydrochloric- acid solutions. In all of the subsequent 
series reported in this bulletin the former method was used. 
SERIES III — AMMONIFICATION OF EQUAL AMOUNTS OF NITROGEN. 
In this series the nitrogenous materials were added so as to furnish 
equal amounts of nitrogen (132.9 milligrams). These and 1 gram of 
calcium carbonate were mixed with 100 grams of the same fresh soil. 
After bringing the moisture content to 25 per cent and incubating 
as before the yields of ammonia were as follows: 
Amount of ammonia from equal amounts of nitrogen. 
[Average of 2 samples.] 
Period of incubation. 
2 days 
4 days 
6 days 
9 days 
Per cent of total N converted into NH 3 
Nitrogen as ammonia from- 
Casein, 
L.072gm. 
Mg. 
58.3 
74.9 
75.7 
75.2 
56.9 
Dried 
blood, 
1.000 gm. 
Mg. 
4.0 
38.5 
59.6 
65.6 
49.3 
Soybean 
cake 
meal, 
1.605 gm. 
Mg. 
14.9 
47.1 
64.8 
58.6 
48.7 
Cotton- 
seed 
meal, 
2.606 gm. 
Mg. 
17.3 
37.9 
42.6 
40.3 
32. 
Linseed 
meal, 
2.658 gm. 
Mg. 
3.5 
32.9 
39.9 
46.0 
34.6 
