28 
FLORIDA STATE HORTICULTURAL SOCIETY 
The valuable ingredient of “cyanamid’’ 
is the calcium cyanamide (CaCN2). It 
is this component that kills the nematodes 
and adds the plant food to the soil. When 
moderate doses are mixed with soil, cal¬ 
cium cyanamide quickly disintegrates, 
probably changing first to urea and then 
to ammonia, and then to nitrates. In 
large doses, however, some of it may go 
into a polymeric form called “dicyana- 
mide." This disintegrates more slowly 
and has a very harmful effect on any crop 
that is planted too soon after the applica¬ 
tion of the cyanamid. This scorching is 
much more pronounced when the soil is 
dry. Too large an amount of cyanamide 
will have the same effect even if no dicy- 
anamide is formed. As stated above, our 
first experiments were with radishes. On 
November 30, 1914, six small plots, each 
containing three square yards, were treat¬ 
ed with cyanamid in quantities varying 
from three tons to 200 pounds per acre. 
The cyanamid was applied as a top dres¬ 
sing, and hoed in. Four similar plots 
were used as checks. These plots were on 
land known to be heavily infested with 
nematodes. On December 4, radishes 
were planted on these plots but a very 
poor stand was obtained and the plots 
were replanted on December 13. On 
March 18 and April 20 the radishes were 
gathered. 
This experiment seemed to indicate 
that: 
(1) Cyanamid used at the rate of 
1600 pounds or more per acre markedly 
reduced the number of nematodes pres¬ 
ent. 
(2) If used too strong or applied too 
near the time of planting it inhibits 
growth or entirely kills the young seed¬ 
lings. 
In March, T915, we started experi¬ 
ments with cowpeas on plots containing a 
hundredth of an acre each. The larger 
size of the plots were intended to reduce 
the danger of the results being obscured 
by the migration of the worms into the 
plots from the sides. To prevent the 
nematodes from being washed over the 
plots from the surrounding land, the plots 
were ridged so that they were slightly 
higher in the middle. The cyanamid was 
applied as a top dressing and worked into 
the soil with a disk harrow. The dosage 
varied from 300 pounds to a ton per acre. 
Cowpeas were planted three weeeks af¬ 
ter the application of the cyanamid. They 
did well until dry weather set in when all 
of those on plots that had received 600 
pounds or more per acre showed signs of 
scorching. On those plots that had re¬ 
ceived 1500 pounds or more per acre the 
cowpeas were not as good as on the check 
plots that had received nothing. On those 
plots that had received 1500 pounds or 
more per acre, there were at first, few 
knots on the roots that did not extend 
to a depth of more than six inches, while 
on the check plots the roots were knotted 
to the very crown. Three months later 
the nematodes had worked up so that 
on the treated plots there began to be 
knots nearer the surface. Evidently we 
had failed to get the material down to a 
sufficient depth. However, the plots that 
had received but 300 pounds per acre 
showed fewer knots than the checks. 
EXPERIMENTS IN GREENHOUSE 
A bench in the Station greenhouse was 
filled with infested soil and then divided 
