72 
Journal of Agricultural Research 
Vol. XXIX, No. 2 
ferences in the percentage of crude 
protein among the three chief groups 
of peat materials. There is a consider¬ 
able increase in the amount of crude 
protein, from 14.95 to 24.44 per cent, 
in the reed peat from Ohio in its raw 
condition, and after it has been trans¬ 
formed into “muck” by cultivation. 
In the present state of our knowledge 
concerning the particular type of 
nitrogenous compounds in different 
types of peat the term crude protein 
is inadequate to cope with the accumu¬ 
lated facts. For reasons given in the 
following section not much significance 
can be attached to the amounts of 
crude protein obtained, at least in so 
far as the agricultural use of this 
material is concerned. 
The proteins and amides are sub¬ 
divided on the basis of the nature of 
their products of hydrolysis and upon 
the solubilities of the individual com¬ 
pounds. For a rough division the nitro¬ 
gen insoluble in lead-acetate solution 
is considered protein nitrogen. The 
nitrogen that is evolved as ammonia 
upon treatment with acid, subse¬ 
quently distilled by potash but not by 
calcium carbonate, is considered as 
amide nitrogen. However, it is not 
yet well understood to what extent 
these terms may be applied to the 
fractions obtained from the different 
kinds of peat. 
A review dealing with the study of 
proteins and amides in soils and peat is 
available in the literature given be¬ 
low; hence it is unnecessary to go 
into any detail here. As early as 
1844 Mulder (84), continuing the in¬ 
vestigations made by*Einhof, Sprengel, 
and others, pointed out that the organic 
nitrogenous material in soils is largely 
of protein origin. Later, Detmer 
(10) observed that a considerable por¬ 
tion of this nitrogen could be liberated 
by adding nitrous acid. Jodidi (21) 
determined the relative quantities of 
mono- and diamino-acid nitrogen to¬ 
gether with the nitrogen obtained as 
ammonia from a fibrous sedge peat. 
Similarly Suzuki (51) reported that he 
isolated such compounds in a material 
derived from peat. Robinson (38) 
found that treatment of peat with 
acid, and lengthening the time of hy¬ 
drolysis increased the amount of 
amino nitrogen, until it reached a 
constant maximum. Robinson con¬ 
cluded that in comparison with ordi¬ 
nary proteins the amino group of peat 
nitrogen did not exist free but in some 
resistant form of combination which 
differed radically from the acid amides. 
Gortner (16), working with three differ¬ 
ent but undetermined kinds of peat, ob¬ 
tained a maximum of 7.5 per cent of total 
nitrogen soluble in 1 per cent hydro¬ 
chloric acid, and an average of 3.78 per 
cent; in five samples of unchanged 
vegetable materials (oat straw, alfalfa 
hay, oak leaves, sweet-fern leaves and 
grasses from a peat bog) he found a 
maximum of 34.58 per cent and an 
average of 20.10 per cent. According 
to Gortner, these findings would in¬ 
dicate that in the humification of 
vegetable materials there is a decrease 
in total nitrogen soluble in very dilute 
acids. Later, Morrow and Gortner 
(33) studied the amounts of the various 
forms of nitrogen isolated from samples 
of sphagnum peat and from material 
to be identified, it seems, as sedge and 
sedimentary types of peat. It is quite 
possible that the material designated 
by the authors as “sphagnum peat and 
subsoil” would be found to consist of 
a layer of sphagnum on sedge peat, 
and that the “calcareous black peat” 
is of pond-formed origin, while the 
analyzed “muck” is sedge peat under 
cultivation. 
Mdller and Robinson (89) divided the 
acid soluble nitrogen in peat materials 
into ammonia nitrogen, acid amide nitro¬ 
gen, and amino nitrogen, calling atten¬ 
tion to the fact that the largest two frac¬ 
tions are the acid amides and the mono¬ 
amino acids. They further point out 
that, contrary to a statement fre¬ 
quently found in the literature, there 
is no regular increase in nitrogen con¬ 
tent with depth or age of the peat 
material, the fluctuations being de¬ 
termined rather by differences in the 
botanical composition of the various 
layers of peat. These results are in 
accordance with those of Zailer and 
Wilk (53), Bersch (2), Minssen (32), 
and others, outlined in Bulletin 802 (8 ). 
In regard to the decomposition of 
peat materials, the results of both 
American and Eurasian peat investi¬ 
gations are of much interest. They 
indicate that during the accumulation 
of plant remains as peat, the protein 
bodies are profoundly altered. Con¬ 
tinued submersion of layers of peat in 
water renders difficult the conversion of 
their nitrogen into ammonia. A high 
water level precludes both oxidation of 
the compounds involved and favorable 
bacterial activity. When submerged, 
the transition of the plant remains to 
peat materials is usually a rapid one; 
this also accounts for the greater 
stability of peat nitrogen. Many of 
these substances remain unavailable 
even after the water-logged layers of 
peat have been drained and aerated. 
Some of the nitrogen may be split off 
by heating, steaming, or treating the 
