Mar. ao, 1916 Relation of Green Manures to Failure of Seedlings 
1167 
EFFECT OF SOIL TYPE 
In order to ascertain the relation to soil type of the agent causing a 
decrease in germination, a series of tests was made. Four soil types 
were used; Colby silt loam, Miami silt loam, Sparta acid sand, and neutral 
sand. The results of the first test are given in Table VIII. 
Table VIII .—Effect of green manure on the germination of cottonseed 
Germination. 
Rela¬ 
tive. 
No. 
Soil. 
Treatment. 
1 
week. 
2 
weeks. 
weeks. 
I 
Colby silt loam (acid)........ 
None... 
Per ct. 
90 
Per ct. 
90 
Per ct. 
90 
Per ct. 
IOO 
2 
3 
4 
Miami silt loam. , . . 
1 per cent of clover. 
None. 
35 
75 
35 
45 
75 
35 
50 
75 
35 
55 
100 
.do. 
1 per cent of clover. 
5 ° 
5 
Miami silt loam, half sand.... 
None. 
95 
95 
95 
IOO 
6 
.do. 
1 per cent of clover. 
45 
45 
45 
50 
7 
8 
^and . 
None. 
80 
80 
80 
IOO 
.do. 
1 per cent of clover. 
90 
90 
90 
112 
9 
10 
Sparta acid sand. 
None. 
80 
80 
85 
70 
IOO 
.do. 
1 per cent of clover. 
70 
70 
82 
For the purpose of securing variation in texture, dilutions with Miami 
soil and quartz sand were made. From the data obtained, it seems that 
the property of reducing seed germination is common to both silt loams, 
but is absent or almost inactive in the sands. Since the relative decrease 
in germination is approximately the same with Miami or Colby silt loam, 
it appears that soil reaction is not one of the controlling factors. In 
neutral or acid sand no decided injury was noted. The results of a 
second series of tests confirm the above statement. Just why sandy 
soil should prove less efficient than the loams is not evident from the data, 
unless it is due to the absence of the injurious factor. 
EFFECT OF POSITION OF GREEN MANURE 
It was arranged to study the effect on seed germination of plant 
tissue at different depths. Green clover was added at the rate of 1 per 
cent. The results secured were as follows: When the green manure 
was placed in the bottom of the jar, 80 per cent of cotton germinated; 
in the middle, none germinated; on top, 10 per cent germinated. It is 
evident that green clover must be in close contact with the seed in order 
to be effective. This may be shown by wrapping cotton seeds with clover 
leaves. One or two clover leaves greatly injured seed germination. 
Plate LXXXIII, figure 4, shows the effect of position of green manure 
on seed germination. 
