Jefferson (1955) reported that the "mowrin" of mowrah meal was 
the active earthworm expellent. He used it in preference to other 
expellents in his earthworm population studies in England. However, he 
did not report the specific methods of application. He recommended that 
any expellent be used only during the spring or fall, when soil moisture 
and soil temperatures were conducive to earthworm activity in the upper 
soil levels. 
Rotenone 
Rotenone (derris root) also has been used as an expellent as 
well as a toxicant. Bingley (1949) reported its value as an expellent, 
but also commented on its cost. 
Harris (1949) reported "optimum" kills of earthworms 24 hours 
after application of 4% rotenone at the rate of about 6 pounds of chemi- 
cal per acre. This treatment remained toxic to worms for 6 more days. 
No further information was given concerning soil type, season, species 
of worm, or other factors. 
INORGANIC CHEMICALS 
Ammonium Sulfate 
Rodale (1948) reported that 500 1b/A of 4-12-4, ammonium 
sulfate, or superphosphate reduced populations, activity (as shown by 
casts), and reproduction of worms. Worms were kept in 6-inch pots where 
activity and populations were checked in detail after 2 months. At 
rates of 1,000 and 1,500 lb/A, the chemicals reduced populations further, 
sometimes killing all worms present. 
Jefferson (1955) used experimental plots to determine the 
effects of various fertilizers upon earthworm population numbers, species, 
and reproduction. The results often were difficult to measure quanti- 
tatively because of climatic changes and the apparently normal popula- 
tion fluctuations. However, the smallest number of species (two) was 
found on plots treated with ammonium sulfate. Plots treated with dried 
blood (considered excellent fertilizer) contained up to 10 species. 
The higher acidity that followed the use of ammonium sulfate was tolerated 
only by Lumbricus rubellus and Allolobophora caliginosa. Jefferson 
concluded that "a comparison of the population estimates in 1947 and 
1953-54 suggested that a real population decline had taken place in 
some habitats, e.g., complete fertilizer plots (ammonium sulfate)}...." 
