RELATION OF GREEN MANURES TO THE FAILURE OF 
CERTAIN SEEDLINGS 
By E. B. Fred, 
Agricultural Bacteriologist , Agricultural Experiment Station of the 
University of Wisconsin 1 
INTRODUCTION 
In a previous report it has been shown that if green manures are turned 
under and the soil planted immediately, a decrease in germination may 
result. For example, a 20-acre field, half in crimson clover {Trifolium 
incarnatum) and half in fallow, was plowed and planted to cotton (Gos- 
sypium spp.) (17, p. 26). 2 On the crimson-clover plot the cotton failed 
almost completely to germinate. Here and there a few crippled seedlings 
appeared, while on the fallowed plot normal germination occurred. Seed 
from the same lot was used on both plots. The green manure in some 
way seriously affected the germination of the cottonseed. Three weeks 
later the green-manure plot was again seeded to cotton. Germination at 
this time was perfectly normal. Apparently the harmful factor disap¬ 
peared during the interval of three weeks. 
A more extensive study of the substances affecting seed germination 
and of the factors involved was deemed advisable. The controlling idea 
in this investigation was a study of the effect of green manures on the 
germination of different seeds. In determining the percentage of germi¬ 
nation, only those seedlings that appeared above the surface are recorded. 
The amount of green manure used was determined from the following 
calculation: A good crop of clover should yield from 4 to 5 tons of undried 
green hay per acre. If 1 acre of soil 3 inches deep weighs 1,000,000 
pounds, then 1 per cent of green clover is comparable to the amount 
employed under field conditions. Except in rare cases this amount of 
green manure was used in all of the laboratory studies. The green plant 
tissue was cut just before blooms began to form, finely chopped, and 
mixed thoroughly with Miami silt loam soil from the Experiment Station 
farm. The soil moisture was maintained at 50 per cent saturation. 
All tests of germination are recorded in percentages. Photographs were 
made of the young seedlings two weeks after planting. 
EFFECT OF GREEN MANURES ON THE GERMINATION OF VARIOUS 
SEEDS 
Since it has been shown that seeds of different plants vary widely in 
chemical composition, it is very probable that they will react differently 
toward green manures. This experiment was planned to test the effect 
1 Published with the permission of the Director of the Wisconsin Agricultural Experiment Station. 
* Reference is made by number to " literature cited," p. 1175-1176. 
Journal of Agricultural Research, Vol. V, No. 25 
Dept, of Agriculture, Washington, D. C. Mar. 20,1916 
ct Wis.—4 
27467°—16 - 2 
(n6i) 
