18 
superiority of ammonium sulphate over organic forms of nitrogen 
are discussed in greater detail on page 21. In this connection it is 
of interest to point out that the plant absorbs the principal part of 
its nitrogen during the early period of its growth ; 1 readily available 
nitrogen therefore is' needed when the rice is young, and since the 
production of available nitrogen from organic forms requires consid- 
erable time the application should be made some time in advance of 
planting, a precaution that was not taken in the above experiments. 
Through a period of years, however, the total effects would probably 
become more nearly equal. 
AMMONIFICATION AND NITRIFICATION IN RICE SOILS. 
The analysis of a number of rice soils taken from the field when 
wet and analyzed immediately has shown that rice soils contain con- 
siderable quantities of ammonia, varying from a few parts up to as 
much as 50 or 60 parts per million. 2 On the other hand, in the sub- 
merged condition nitrate is rarely found in more than mere traces, 
frequently being entirely absent. 
Since good effects are known to follow the use of organic manures, 
and, furthermore, that ammoniacal nitrogen is especially effective 
with rice, it becomes a matter of interest to ascertain whether or not 
ammonia is formed in rice soils at rates sufficient to supply the needs 
of rice. 
Accordingly a series of ammonification experiments were carried 
out with dried blood as the source of nitrogen, using varying amounts 
of water, starting in with the air-dry condition and increasing the 
amounts of water applied up to and beyond the saturation point. 
One hundred gram portions of soil were placed in tumblers with 2 
grams of dried blood added to each. After an incubation period of 
seven days the ammonia was determined by distilling with mag- 
nesium oxid into standard acid. The results obtained were as fol- 
lows : 
Influence of varying amounts of water on the ammonification of dried hlood. 
Water added. 
Nitrogen found as 
ammonia. 
Water added. 
Nitrogen found as 
ammonia. 
Soil 292. 
Soil 461. 
Soil 292. 
Soil 461. 
Mg. 
2.2 
2.2 
37.8 
Mg. 
3.9 
5.1 
4.3 
25.5 
41.2 
53.2 
59.0 
35 cc 
Mg. 
131.1 
Mg. 
86.8 
40 cc. . 
90.5 
<54.5 
:>n. 7 
85.4 
10 cc... 
71.2 
15 cc 
164.9 
85. 3 
20 cc 
165.5 
164.6 
140. 1 
55 cc 48.2 
65 cc 
52.4 
25 cc 
< 15.1 
30 cc 
70 cc 
16.1 
1 Hawaii Sta. Bui. 21. 
2 Fraps also showed in 1908 that ammonification takes place much more vigorously 
rice soils of Texas than does nitrification (Texas Sta. Bui. 82). 
8 Each soil contained about 5 per cent moisture. 
4 Saturated. 
