Mar. so, 1916 Relation of Green Manures to Failure of Seedlings 1169 
Since it was established that ammonia is harmful to seed germination, 
another test was carried out to study the ammonia produced by micro¬ 
organisms. The results of this study are shown in Table X. 
Table X.— Effect of sugar and of clover on armnonification 
Time in 2-day intervals. 
Ammonia nitrogen in 100 gm. of soil. 
No treat¬ 
ment. 
1 per cent of 
sugar added. 
1 per cent of 
clover added. 
Mgm. 
I. 98 
Mgm. 
2 . 0 
2. I 
I. 96 
1.4 
1. 4 
2. 5 
Mgm. 
3-3 
4.3 
2. 8 
2.4 
2. 5 
2. 6 
0 * " ' 
6 . 
1. 90 
Total . 
11. 36 
17.9 
Since ammonia formation is largely a product of bacterial action, it 
was thought that sugar or green manure would cause an enormous 
increase in this substance. The data of Table X show a slight gain in 
ammonia in the treated soils, but the amount is far too small to affect 
germination seriously 
CARBON DIOXID 
It was found that carbon dioxid, when added in large quantities, re¬ 
tards germination but does not cause the seeds to decay. As soon as 
the carbon dioxid is removed, germination proceeds in a normal manner. 
In Table XI is given the periodic evolution of carbon dioxid from soil 
treated with i per cent of sugar and i per cent of clover. 
Table XI.— Effect of sugar and clover on carbon-dioxid evolution 
Carbon dioxid in 100 gm. of soil. 
Time in days. 
No treatment. 
1 per cent of 
sugar added. 
i per cent of 
clover added. 
Mgm. 
4. 62 
6. 82 
9. 46 
7. 21 
7 - 57 
7 * 74 
7 - 65 
9. 68 
Mgm. 
22 . O 
17. 2 
36. 5 2 
37-84 
33 - 97 
29.35 
26. 40 
25 * 30 
Mgm. 
16. 02 
12. 7 
22. O 
22. 75 
22. 7 
24, 2 
24.42 
22. 22 
6. 
8.. 
Total. 
60.75 
228. 58 
167. 01 
