38 
Journal of Agricultural Research 
Vol. XXVIII, No. 1 
various crops to the products produced. However, only a few of these which 
throw light on the nature of the cyanamid changes, particularly those resulting 
from biological action, are mentioned here. The work is discussed approximately 
in the order reported. 
Lohnis (IS) 2 stated that on laboratory culture media cyanamid was converted 
into ammonia by bacterial action in the same manner as that of urea but at a 
slower rate. Dicyanodiamid was also formed in the absence of microorganisms 
by the action of water. Perotti (22) obtained results quite similar to those 
reported by Lohnis. 
Kappen (9) found that in loam soil the transformation of cyanamid was 
very rapid and only small percentages of dicyanodiamid were formed. He at¬ 
tributed the first poisonous effects on plants following top dressings of cyanamid 
on acid soils to cyanamid, the later effects to dicyanodiamid. 
Muntz and Nottin (21) obtained a* lower rate of nitrification of calcium cyan¬ 
amid than of ammonium sulphate when used in relatively large amounts but found 
little difference at the lower rates. They attributed the retardation to the cyan¬ 
amid, itself, and not to the caustic lime present. Likewise, Lipman and Brown 
(12) found that cyanamid was injurious to nitrifying bacteria. 
Lohnis and Sabaschnikoff (16) stated that cyanamid is not converted to any 
appreciable extent into ammonia in sterile soils but microorganisms are neces¬ 
sary for the change. Contrary to the opinion of Lohnis, Ulpiani (26, 27) con¬ 
cluded from his studies that cyanamid is not converted into ammonia by bacteria, 
but easily changes into dicyanodiamid, urea, and other compounds. The 
dicyanodiamid and urea are both converted into ammonia. In a subsequent paper 
(15) Lohnis and Moll agreed with Ulpiani that there is no direct bacterial action 
on cyanamid, but that microorganisms are responsible for the formation of 
ammonia from the urea, first produced from cyanamid by soil colloids. On the 
other hand, Kappen (10) claimed to have found five species of fungi which 
readily attacked cyanamid. 
Stutzer, Reis, and Soli (25) believed that the formation of ammonia from 
cyanamid was due chiefly to chemical action but, nevertheless, claimed that 
cyanamid but not dicyanodiamid can be utilized by microorganisms as a source 
of nitrogen. Brioux (2) found that in soil some cyanamid polymerizes into 
dicyanodiamid but that the latter is quickly converted into ammonia. 
The importance of colloids was emphasized by several investigators, Henschel 
(7) having obtained a somewhat more rapid decomposition of cyanamid in dry 
sterilized soils and colloids than in the unsterilized. The presence of humus 
was of especial importance. Milo (20) studied the decomposition of cyanamid in 
soils and states that in heavy, strongly absorbent soils, high in colloidal matter 
urea is quickly formed by chemico-physical action. The urea is in turn changed 
to ammonium carbonate probably by microorganisms. In light soils the calcium 
cyanamid formed basic calcium cyanamid salts and free cyanamid. Ammonia 
was formed from these very slowly, thus giving time for dicyanodiamid forma¬ 
tion. Lohnis (14) as a result of further studies, similar to those mentioned,, 
agreed with Kappen that soil fungi are able to attack cyanamid directly but 
emphasized that normally cyanamid is changed into urea by means of colloids 
and that this is in turn changed into ammonia and nitrates by biological action. 
Maze and Lemoigne (19) found that a number of common soil bacteria are 
capable of converting cyanamid into urea. This change takes place rapidly in 
fertile soils, rich in humus, but slowly in acid soils. The urea is quickly changed 
to ammonia and nitrates. 
Cowie (S) in a study of the chemistry of cyanamid changes in soil reported 
that cyanamid is readily changed to ammonia and nitrates in the absence of 
dicyanodiamid. When the latter compound is present ammonia accumulates 
2 Reference is made by number (italic) to “ Literature cited,” p. 68-69. 
