n66 
Journal of Agricultural Research 
Vol. V, No. 25 
Tabi<E VII .—Effect of oats on the germination of various seeds 
No. 
Seed. 
Germination of seed. 
Planted immediately af¬ 
ter turning under. 
Planted 25 days after 
turning under. 
With oats. 
Unplanted. 
With oats. 
Unplanted. 
I 
Cotton. 
IOO 
210 
134 
140 
2 
.do. 
117 
2l8 
12$ 
131 
3 
Com... 
62 
75 
72 
73 
4 
Hemp. 
45 ° 
1,130 
210 
320 
5 
Oats. 
Many. 
Many. 
Many. 
Many. 
6 
Soybean. 
35 
88 
39 
40 
From these tables it will be seen that green manures seriously injure 
the germination of cotton, soybeans, and hemp, while com and oats are 
not affected. The diminished germination is not confined to clover 
tissue, but is noted with oats. This effect of the plant tissue on germi¬ 
nating seeds is also observed in the weight of harvest. Unfortunately, 
because of climatic conditions, the cotton could not be grown to matu¬ 
rity. On adjoining plots, where the green manure was allowed to decom¬ 
pose for 25 days before planting, no injury was observed. 
The field data show (1) that green manures largely prevent the germi¬ 
nation of certain oil seeds, and (2) that the unfavorable condition is 
only temporary. 
NATURE OF THE INJURIOUS AGENT 
There are a number of possible causes that might account for the 
destructive influence of green manures on seed germination: 
First, the green manure greatly increases the number and variety of 
micro-organisms. The organisms on the plant tissue may be harmful, 
or conditions proper for the development of harmful organisms may 
arise. 
Second, the large gain in number of organisms, after the addition of 
green manure, results in a possible accumulation of substances toxic to 
germination—for example, poisonous by-products of decomposition, as 
alkali or acid. 
Third, the rapid multiplication of micro-organisms, which results in an 
increased metabolism, causes soil oxygen to be consumed and carbon 
dioxid to be given off. Such loss in oxygen and gain in carbon dioxid 
might conceivably retard or prevent germination. If it is assumed that 
oil seeds require more oxygen for germination than starch seeds, the 
third supposition should apply particularly to seeds rich in fat (16, p. 173). 
