Ii68 
Journal of Agricultural Research 
Vol. V, No. as 
EFFECT OF INCREASED AERATION 
In view of the different action of green manures in compact and open 
soils, it was decided to make a series of tests under conditions that tend 
to remove gaseous substances. For this purpose, specially designed 
jars with openings in their bottoms were employed. By means of a 
glass tube connected with the bottoms of the jars, air was forced through 
the soil. In these tests air was allowed to pass through the soil for 
20 to 30 minutes every day. A comparison of germination in the aerated 
and unaerated soils failed to show any difference. Change in soil air 
did not lessen the injury. 
EFFECT OF TEMPERATURE 
It is a well-known fact that slight changes in temperature often greatly 
increase or decrease the growth of micro-organisms. Accordingly a 
test was made with three variations in temperature. 
Table IX .—Effect of temperature on germination of cottonseed 
No. 
Treatment. 
Tempera¬ 
ture. 
Germination. 
Relative. 
4 days. 
8 days. 
•c. 
Per cent. 
Per cent. 
Per cent. 
1 
None. 
2 5 
85 
85 
100 
2 
1 per cent of clover. 
2 5 
55 
55 
64 
3 
None. 
30 
95 
95 
IOO 
4 
1 per cent of clover... 
30 
35 
35 
36 
5 
None. 
37 
100 
100 
IOO 
6 
1 per cent of clover. 
37 
80 
80 
80 
About 30° C. seems to give the greatest injury; lower or higher tem¬ 
peratures fail to cause so great a decrease in germination. 
EFFECT OF CERTAIN DECOMPOSITION PRODUCTS 
In the decomposition of plant tissue many substances are liberated— 
e. g., ammonia and carbon dioxid. The relation of ammonium hydroxid 
to seed germination has been studied by Bokorny (3; 4, p. 37). He 
found that small quantities of ammonium hydroxid, 0.02 per cent, 
greatly retarded the germination of cress. It seems that the active pro¬ 
tein of the cell is very sensitive to ammonia. 
AMMONIUM HYDROXID 
A series of tests was made using from 0.1 to 0.01 per cent of ammonium 
hydroxid. Four different seeds, cotton, com, soybeans, and wheat, were 
allowed to germinate between cloths saturated with the varying concen¬ 
trations of ammonium hydroxid. It was found that 0.05 or 0.01 per 
cent proved injurious, while 0.1 per cent prohibited all germination. 
