The organic nitrogen of Hawaiian soils

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Material Information

Title:
The organic nitrogen of Hawaiian soils
Series Title:
Bulletin / Hawaii Agricultural Experiment Station ;
Physical Description:
22 p. : ; 23 cm.
Language:
English
Creator:
Kelley, W. P ( Walter Pearson ), b. 1878
Merrill, Alice Ranney Thompson, 1883-
Publisher:
G.P.O.
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Soils -- Hawaii   ( lcsh )
Soils -- Analysis   ( lcsh )
Soils -- Nitrogen content -- Hawaii   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references.
Statement of Responsibility:
by W.P. Kelley and Alice R. Thompson.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029613269
oclc - 10055802
Classification:
lcc - S399 .E2 no.33
System ID:
AA00014538:00001


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tNDER THE HUPERVIBION OF

OFFICE OF EXPERIMENT STATIONS,

U. S. DEPARTMENT OF AGRICULTURE.


WASHINGTON:

GOVERNMENT PRINTING OFFICE.

1914.


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STATIONN STAFF.
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HAWAII AGRICULTURALT EXPERIMENT STATION' H0TOs

[Under the supervision of A. C. TRUz, Director of the Office, olX xp,'i t Statlons, -TZt.d i
apartment of Agriculturl .', :,

WAMEBR H. EVANS, Chiefof Divimon of Insular 8tationm, Offi of Exp r'
.. ... .. ... '.... .
STATION STAFF. :
:


E. V.. Wacox, Special Agent in Charge.
J. EDGAR HIGGINS, Horticulturist.
W. P. KELLEY, Chemist.
C. K. MCCLELLAND, Agronomist.
D. T. FULLAWAY, Entomologist.
W. T. MCGEORGE, Assistant Chemist.
ALICE R. THOMPSON, Assistant Chemist.
C. J. HUNN, Assistant Horticulturist.
V. S. HOLT, Assistant in Horticulture.
C. A. SAHR, Assistant in Agronomy.
F. A. CLOWES, Superintendent Hawaii Substations.
W. A. ANDERSON, Superintendent Rubber Substation.
J. DE C. JERVES, Superintendent Homestead Substation.
JOSEPH K. CLARK, Superintendent Waipio Substation.
GEORGE COPP, Superintendent Kula Substation.

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Ilct .of various vegetable proteids when acted upon by bacteria.
Respectfully,
SE. V. WILCOX,
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SDirector ffice of Experiment Stations,
SD8. r A Department of Agriculture, Washington, D. C.

Publication recommended.
A. C. TauE, Director.

Publication authorized.
D. F. HousTON, Seretary of Agriculture.








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CONTENTS.


.,. _' : l
.. .. ... ...
Introduction.... ..--..------.. ---- -------------- ...... ....,- .. :..
The nitrogen of Hawaiian soils. -.... ......."......... ........ .
Nitrate and ammonia-......................................... ..
Organic nitrogen..........................................ia...... .-------------------------------- -T
Organic nitrogen ........ ....... ........ ............. ..... ...
Amids .... ... ................- ....... ........ ................ ,. ...
Basic nitrogen
Nonbasic nitrogen. .................. .... ....... ..............
Effects of aeration on soil nitrogen.....................................
HEumus nitrogen.................................... ........:
Humus nitrogen-. -------------------------------.......................;. t^-*W
Nitrogen dissolved in the preliminary 1 per cent hydrochloric acid extra,- I
tion. ................................... .. ................... ... I.
Separation of different forms of nitrogen in humus........- ........... 3
Amid nitrogen--------------------------- i
Amid nitrogen........................................... ......... ... 10'l.
Basic nitrogen............ .. ......................-- .............. 1I
Nonbasic nitrogen....--.....----..-.----.-------------------......................---- 1
Determination of humus nitrogen....................................... ..-i I'..
Percentage of nitrogen in humus of Hawaiian soils ................... .- -
Summary... ... ............ ......................................... ........
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..GANIC NITROGEN OF... HAWAIIAN SOILS,


INTRDUCTION.
greater part of iaoil nitrogen may reasonably be assumed to hitve
bound up at one time or another in -protein, combinations, smice-
Afroe in -the mai has been derived: from vegetable sources.
aMounts, of other. nitrogerubodies, such -as alkaloids, etc.,
A"'ul their way into soils but -the nitrogeA from.such compounds
'Odhardly he expected to amount to more than:&.9mall percentage
'OPAMtotWlintrogen present.. The chemistry of soil nitrogen and the
~that, it undergoes, therefore% must be largely those of plant
brought about, under complex and indeed extremely varlia-
iiA great host of organisms inhabiting soils are asso-
with the transformtatons of the o'rganic nitrogen bodies, and
Owxditons and environmet in which the organisms- function
p* Wl msterialy alter the: rates of their action but also determine
6'arb.Th rsneoly -what, the end products shl be h rsneo various,
leglet ubtances, both organic .and .inorganic, the acidity or
ty andthe degree of porosity of: the soil, all exert important
Seces on the activity-of soil organisms,
*1F*1Dd~ g -the past: few years considerable study has been devoted
Vw the nitrogen compounds of the soil. In 1905-6, Shorey,' while
4hemist: at: this stations, applied to a coffee soil from the island of
Uawaii :the. methods formerly used in the study of protein, and thus
Aeaermned. the amounts of basic, nonbasic, ammonia nitrogen, etc.,
agilit off by means of boiling acid&. In connection with his studies
a pyrdin derivative, -picolin carboxylic acid, was isolated and identi-
fody this being the first definite organic nitrogen compound to be
isolted. from a soil. Recently -a number of other studies on soil
vitroen have. been reported.2
The researches previously made on this subject naturally divide
theselesinto two classes, as indicated by the work of Shorey.

-soils-eond, a study of the products formed by acid hydrolysis.

$'11w& t&. Rfpt UNA6 pp. 37-Mi.
SOS*ffebigan M6a Tech. Bul. 4 (1909); Iowa Sts Research Bols. I and 3 (1911); Robbinon MI&hiad
00aekSL. 74(1911); Lahopad B~rown Pennsylvania Sta. Rpt 1910, RP. 11S120 lour. Indus. =4
xadn, 8&0 (191)" pp. 067-M40
U.&Dp g. M d 31 7 o709, 7
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compounds split off in the treatment, and although only aff
tively small number of soils have been studied, these, n, it
have been found to yield the greatest amount of nitrogMe in th.
of monamino acids. Approximately 25 per cent of the .ii
split off was in the form of amids, while the diamino ni
been found in still smaller amounts, usually not more than .10.p
of the total nitrogen dissolved.
It is not necessary to discuss in detail the studies previously
on this subject. It is sufficient to say that too much import i.,
hardly be given to the nitrogen of soils. The element lieft :;.
foundation of plant growth. The use of nitrogenous foe i
assumed enormous proportions throughout the world. In ..
extremely heavy applications have been made for many yeawv;iI
the tendency during the past few years has been toward even p.
applications. Many of the soils, however, contain a relativelyi4
percentage of nitrogen. In some instances, even where veryJui
applications of nitrogenous fertilizers are made, the soils contoainqi
per cent or more of nitrogen.. '. :
Investigations on nitrification and ammonificatfon in differM
Hawaiian soils have been under way in this laboratory for some tin
and the results obtained have been of such nature as to emphasize t
need for a better understanding of the chemical nature of the nitrog(
bodies contained in these soils. Studies have accordingly been uni
taken on this subject, employing the process of acid hydrolysis. .i
this work the nitrogen as a whole has been studied by subjeotinfl
hydrolysis weighed portions of the original soils. On account of .
great importance generally attached to humus, and the limited ,.j
of knowledge concerning the chemistry of this material, some stui
was devoted to the alkali soluble nitrogen bodies.
Since the substances to be investigated originally came from aM
ber of plants, the protein of which has not been sufficiently studio
and have probably already undergone much change through the aoti
of bacteria, there are no definitely understood materials to start wi
The hydrolytic products obtained, therefore, leave much room f
speculation. Just how far the cleavages had already gone in theb-i
previous to treatment remains a matter for much further workbefo.
definite conclusions can be drawn.
1 Loc. cit.
















































of Oahu, and have been devoted to aquatic agriculture for many
the former to rice and the latter to taro.

NITRATE AND AMMONIA,

na deemedi .interest to determine the amounts of nitrate and
E present in the soil preliminary to a study of the organic
tituents. Nitrate was determined from water solutions, by the
.i...f the phenol-disulphonic acid method, while the ammonia was
...... by the direct distillation of separate portions of the soil
inbi mangneinum oxid. The results calculated to the water-free basis
;igipvenI in the following table:
.' To2tal nitrate and ammonia nitrogen in Hawaiian soils.


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;i Nitrate nitrogen. Ammania nitrogen.
Total
percent. Partsper t l P oftotal
.i...BollNo nitroge,



S .... ..................................... 0 1002 10 0.189 10 0.100
........-........................................ .770 45 .584 220 2.857
r.............. ................................ .354 62 1.751 10 .328
."...........................---- -..-- .. .12-2 4 .328 10 .819
i .... ............................................. 220 0 .000 22 1.000
................................... .......... .21 0 .000 D 32 1.468
.................................................. 1 0 .64 130 .
: ........ ........ ............................ .195 1 .050 50 2.564
... ..................................... .456 15 .329 60 1.310


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nitrogen compounds occurring in soils must necessarily be
undertaking. It has been shown, however, that by means
hydrolytic method as used in the study of proteikche ndst !
conception can be obtained regarding the make-up of the
bodies of the soil. By the use of this method the amounts of A
split off in the form of amids, diamino, and monamino. i
relatively easily determined. ,
Partly on account of the readiness with which these determine
can be made, and partly for the reason that the soil nitrogen :A
reasonably be supposed to have originated largely from vegbta
proteins, many of which are known to be susceptible to compi
hydrolysis, use has been made of the process of hydrolysis i~:n
work. In addition it seems probable that the action of bacteria 0l
soil nitrogen is progressive and of a hydrolytic nature. ; .
On the other hand, the work of Osborne 2 and others show thAt i
the hydrolytic products vary widely with the different proteins an di
indicate that the results obtained in soil studies by the use of o
hydrolytic agents must be of the most general nature. Neverthdle ,
it is believed that much valuable information can be obtained in, tk
w ay. ... ..:
In the work reported in this bulletin the Osborne-Harris3 mod :..
cation of the Hausmann method, as outlined by Jodidi in h: '
studies on Iowa soils, has been used. The hydrolysis was condud"-..t;
by heating to boiling under a reflux condenser for 10 hours 50-get I:
portions of the air-dried soils with 750 cubic centimeters strong hydrb :
chloric acid, filtering, and making the filtrate to 1 liter. Aliquo*t
of the solution thus obtained were used for the determination of ti:';
amid, basic, and nonbasic nitrogen. The amid nitrogen, determined
as ammonia by the direct distillation of the solutions after mal:daIt
alkaline with magnesium oxid, would also contain the ammonia ori.
SThe occurrence of large quantities of ammonium compounds is a phenomenon common to ma ;l .r
Hawaiian soils. .
2 The Vegetable Proteins. London and New York, 1909.
' Jour. Amer. Chem. Soc., 25 (1903), p. 323. "
SZtschr. Physiol. Chem., 27 (1899), p. 95.
* Iowa Sta. Research Bul. 1 (1911). ;i







































........ 71.96 0. Q05 0.00 0.800 0.426 22.30 7.04 70.42
.715a .. .141 .028 .368 .559 24.79 5.01 66.27
.-."S, .... 7.51 .074 .033 .131 .239 30.96 13.81 54.82
f---.-. 91.8 .024 .012 .075 .112 21.43 10.71 66.96
... 90.91 .054 .020 .124 .200 27.00 10.00 62.00
-5i2....3 ... 88S 5- .042 .017 .131 .193 21.76 8.81 67.88
3. ........ 80.42 .225 .097 .663 .998 22.55 9.72 66.43
... 84.2 .042 .019 .099 .165 25.45 11.51 60.00
... ...... 1.22 .079 .055 .276 .416 18.99 13.22 66.35
L .......: .i...iiv.isi iHL.gp *~.1 sl- ...... 23 91 9.981 64.57

above table shows that there is considerable variation in the
oof soluble 'nitrogen in different soils. In soil No. 447 only
per cent of the total nitrogen was dissolved, while No. 292
.80 per cent. Concerning the insoluble nitrogen very little

AMIDB.

distilling the solutions after making them alkaline with mag-
o oid approximately 25 per cent of the nitrogen in solution was
i t ed in the form of ammonia, here referred to as amid nitrogen,
..ll the soils studied, with the exception of Nos. 447, 343, and 406,
,i isd approximately the same relative amounts of nitrogen as
mi1. It '1 of interest to note that the amids constitute a

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With the results obtained by Jodidi, hawevr, oeur data.a..t
able, and from his work on Michigan peat and Iowa eoils s
of amid nitrogen found were approximatey the same as the
in Hawaiian soils.
BASIC NITROGEN. ....
The percentage of nitrogen precipitated by phosphotungti
was found to vary considerably in the different soils studied,.
on the average to be similar to the amounts reported by JodidV1
these studies no attempt was made to prove the nature of thesenittq
compounds, but from the work of others it seems permissiW
consider them as being composed principally of diamino acids. I
noteworthy that the percentages of basic nitrogen'in soils fi a4
below the percentages found in the majority of vegetable prote"iq
With the exception of glutenin from wheat, gliadin from wheat s&
rye, hordein from barley, and zein from maize, the basic niti
comprises more than 20 per cent of the total nitrogen in the vegetau
proteins previously studied, and in a number of instances even up
than 30 per cent of it. The basic nitrogen compounds of la1 l|
soils comprise only about 10 per cent of the total nitrogen.
Since the principal diamino acids that occur in vegetable pro
are arginin, histidin, and lysin, each of which can be preci
from dilute solutions by phosphotungstic acid, it may be aSA
that these compounds contain the principal diamino nitrogen ap
off in the hydrolysis of soil organic matter. The amounts fLi
vary considerably. This may be accounted for in part by 4th0 A
that the phosphotungstic acid method, in order to give reliable resj
must be conducted under as definite conditions as posai"e. iai
of the presence in the solution of various inorganic aitso la 4olj"
the hydrochloric acid digestion, it is hardly to be supposed ,hAwk
conditions of this precipitate were indentical with the different seil
The precipitate is slightly soluble in the solutions employed, a.








me !iw the, solution. For teerseesm aito

NONBABIO NITWOE*.
frenagsOf non1basic virge fwth fbh'e eteeption (if -that
No. 447, wmr found to be r~e'metkab sibiffir in every k"-
skmounting to about two-thirds of the bitwrogn dissolved by
ky&96eblerle add. 1It this respct the solvble nitrogen of soils
Amarto thst of vegetable proteidk. 116 nonbasic nitrogen
166elb *rpon AN being composd largel, but -not entirelyj of
iiw ftd hobal w6k sr obtie in the hydrolysis
F bbkblnshn, for 6XSWple, isolated: IeMci -and isolenicint
*0io" adid solktion of Michgn peat. Dbubtless- other
o id h ri n 'he :lutaions. ft 'is claimed, however, that
blrportion Of the nonb askc nitrogen of soils occurs in forms
has as Wlnaitno Acidir. Rfobinsou, by the use of the Van S1yke
",idmethod -for the determinationm Of Iftolamino, acids, found
bmy feos monsmino adid.in solktion thah was necessary to ac-
theo iobasie. group, whie Jodidfi arAid it Nimilar conclusions
"0 of the formildehydef titrAtion tfnethod. ONbatne,2 has pre-
",sqwporting the ides thal the noubasic nitrogen obtained
**tlible proteina Acually occurred as monanino ncids. As
00 xI Mata of t"i dference betweenf the nitrogen of soils
*4a Of Vewghtable proteins has been proposed. The soluble non-
nitogn i Iawaiwan stoi&.approitimates thd amounts found in

EFFETS V AMAATION ON SOIL NITMOGES.
Some refereces have already been made to the fact that a wide
p,#Xivein the degree of seration- prevails in different Hawaiian soils,
7 that some of the soils studied in this investigation represent ex-
ih twi respet. BY reference to the previous description of
otit ig seen that soils Nos. 379,; 428, and 447 represent aersted
Mi -Smd 4 .47 particularly so, since they are taken from well
Itad 10 sections where semiarid conditions have prevailed
)Idy yest. Ile remainng soils studied represent anaerbie con-
sifie.e &#eY have been used in aquatic agriculture a large part
tiW6 for many, yests. So far as known no nitrogenous fer-
df Any 0o6A have been applied to any of these doila.
to generely field that the production of gxnmoniA from organic
is 4eceftary before its nitrification can take place, and that ant-
Scan be formed by a wide,,range of soil organisms. Some of these
I TWL Cit. w TM Voentble Protin. London and Now York, 190M






















decay, which evidently predominates in ~t n ge i iL
nitrogen in a form more easily dissolved by hydrohlon
the process of eremacausis, that takes place mudera4AOe.t
The relative amounts of the different groups. obtai
soils representing the two classes of conditions b0,.wev0r,.
to be quite similar in most instances. The table show
and ammonia present (p. 7) indicates that with the.
soils No3. 347 and 406, those representing unaerated condition
trained next to no nitrate. The nitrate found in the r
aerated soils was formed almost entirely during th time of
out in the laboratory. These samples were taken from theI
a wet state and then contained practically no nitrate. In,:
trification scarcely takes place at all in submerged Hawaiia
The data, therefore, fail to give any indication of a fundameint ..
ference in the nature of the hydrolyses which take place under
and anaerobic conditions.
"
HUMUS NITROGEN. .
The alkali soluble organic matter of soils, usually known as u
is generally considered to be of special importance. Only :a.:
the organic matter present in soils occurs as humus, and gen
very little attention is paid to the remaining. For this reason<
study has been given to the nitrogen bodies contained in it." ,i
investigation it was hoped to learn something regarding the c. s
make-up of these bodies by determining the amounts of the dik'
nitrogen groups actually present. Some light was also soogh4 i
question whether or not the alkali soluble nitrogen bodia.e re r
different from the organic nitrogen of soils as a whole. The soils f
1 Hawaii Sta. Bul..31. :.:.:..





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K e by the Kjeldahl method, with the following results:

I' Ntroen :;ofsoils soluble in cold 1 per cent hydrochloric add.
":. .
SPer Per cent Per cent
I .. allNo. ..--- 5 of total Boil No. o of total
nitrogen. nitrogen.
j3Ei:-..:.. *.------- 0.01 3.2 Mi--- ------ --------------------- --------1
3 ...-....... ....... 019 .21 345.....5................ .... 0.007 3.21
....................... .041 5.33 347....--..........-----..----.029 2.34
.. ..3...,.. .... .012 3.9 405.....-.-.- .......... .... .009 4.61
.:--.---------004 3.28 406.......................... .012 2.63
:,~,.- ,,. .. .. 004 1.82


Scomiparing these data with those given in the first table it will
I oen that in every instance the soils contained only about one-half
fith amoiE ma nia nitrogen as was dissolved by 1 per cent hydrochloric
while ~in a number of instances still greater amounts of nitrogen
0T disolved. Some organic nitrogen, therefore, was thus dis-
Ie, although the amounts were small.
n preparing the humus solutions for studies on the nitrogen
Iel a 3 per cent solution of sodium hydrate was employed. With
.w.aiian soils sodium hydrate solution has a special advantage of

I Hawaii Bta. Pres BuLu 3.
Ss Rtnbah, Jor. Amer. Ch 9o. Hoc., 22 (1900), p. 695.


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A part of the humus can be precipitated from the .til
by acids, and this method has been used for.obtaing o
humus. The amounts precipitated, however, vary with t
of acid used. Shorey1 has shown that after SAltering out.::.
cipitate obtained by acidifying the humus solution a still
precipitate can be obtained by 'carefully xeutri- liziMg the'
and that of the precipitates thus obtained each contain: :
The humus extract made with a 2 per cent sodium hyda.t
was found to contain 0.0399 gram nitrogen per 100 cubic
of solution. The hydrochloric acid filtrate he found to cota...
gram of nitrogen per 100 cubic centimeters of the original
and on neutralizing this filtrate with caustic soda. the M
formed was found to contain 0.0168 gram of nitrogen.
In the work here reported hydrochloric acid was carefuySti!''.
to 1,000 cubic centimeter portions of the humus,solution ..(it
spending to 20 grams of soil) to apparent neutrality'to litmus pa r,
then 20 cubic centimeters of 1 per cent hydrochloric acid was a :dd:: :ii
the precipitate formed was collected on a filter and washed. In .
way the humus matter was roughly separated into two parts. T...
precipitates thus obtained were afterwards subjected to acid hy4d
ysis by boiling with 400 cubic centimeters strong hydro-A
acid for a period of 10 hours, and then filtering and washing
residue. The amid and basic nitrogen contained in the o
humus solutions, in the filtrates obtained from precipitating"V!
solutions with dilute hydrochloric acid, and in those obtained
hydrolyzing the humus precipitates, have been determined. ;i!:
The following table shows the total nitrogen contained inm ti;nf
original humus solutions, and that in the portions obtained by '#M*:
various separations:
awai Sta. Rpt. 1 906.










*oipt tr Humus Total Total o- ppta
r;oal uttro- humuu Hoae gnBnt E Q.
...n ro nb n _t_- |i -
nitr- t "o- by 4 --CI. Hydro- hy. .--

I*i:' tit lyuba" lysaeH- BbyCl ua t of Per
a. Itag c.P Pd *,n m" stit cen Nt of
eeoitof eit o f enta at of humus hu
nt ao. oL ntro ns itr '

S. .....-... 0L241 0.362 0.125 0.315 0.808 0.774 62.37 39.28 45.14 15.8#
.2.0 3 .289 .051 .4j .587 ..590 76.M 42.08 49.23 8.90
.. ....... .270 .041 .13 .440 439 74.16 29.33 61.36 9.33
AM -------..- 45 .100 .027 .117 .244 .226 49.56 47.96 40.98 11.06
.. .094 .026 .106 .225 .215 60.79 46.67 41.78 11.58
.l..o ... .066 .019 .070 .155 .147 67.43 45.16 42.58 12.6
.... 3 0. .061 .012 .060 .142 .127 57.33 48.59 42.96 8.45
:..-...- .1 .044- .012 .067 .133 .123 63.08 54.47 35.77 9.76
; :. .. .... .,083 .031 .012 .015 .058 .058 67.54 25.86 53.45 20.69
.4 .----------..-...-.... ........ ........ .. .. 64.36 42.15 45.92 11.93

*:ve dveda show that the humus nitrogen varied with different
lt WBeraged 64.36 per cent of the- total nitrogen. In every
ecept two, more than one-half of the nitrogen was dissolved
lk nli, while in two instances practically three-fourths of it
rJ,.tus extracted. The bodies precipitated with dilute hydro-
Sci also contained nitrogen in varying amounts. The nitro-
:io diqs precipitated by hydrochloric acid upon subsequent
is yielded by far the greater portion of their nitrogen to the
the insoluble residues having been found to contain 11.93
iiertnt of the humus nitrogen. By these methods, therefore, the
of soils can be separated into fractional parts.

., AMID NITROGEN.

iihe a id nitrogen in the original humus solutions was first deter-
,EiB by evaporating the solutions on the water bath, after slightly
i n with hydrochloric acid, then making alkaline with mag-
wMji m oxid and distilling. The relatively high percentages of
mn'a thus obtained suggested that some hydrolysis had taken
1ir during the time of the evaporation on the water bath, possibly
ro te action of the hydrochloric acid present. In order to
ate tthis possibility, separate portions were distilled directly
magnesium oxid, after having been slightly acidified with
rie acid. In like manner the solutions, obtained after
out the humus matter precipitated by hydrochloric acid,
f. distilled with magnesium oxid, and also the solutions obtained





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before ration. rer caa on rere o -o t cA.,
distillation. Per cent of soil. of sai. -b.0
Per cent of soil. nitroI M. -
of soil.

347............... 0.100 0.087 0.095 0.07. 0.18738 1
428................073 .073 074 .056: .130 1 8 I.
379............... .059 .052 .056 .061 .117 19.7t
406............... .039 .028 .040 .60 1.15
447 .............. .033 .026. .031 ..058 1"6.3 9.
345.............. .025 .018 .022 W : .038 17.43 .ii
343.............. .020 .020 .- 025 .018 04 19.54
405............. .026 .017 '014 3 a .0 7 18. 9
292.............. .009 .012 .008 .O1. .019 15.57 .
Average.... ...... .. .... ...... .. ................ ....... 1680

The relatively high percentages of amid nitrogen bt in .
original humus solutions is noteworthy, as is also the factv.
nitrogen bodies not precipitated by hydrochloric acid
practically all of the amid nitrogen existing as such in tb $h'h
solution. On an average, the hydrochloric acid precipitate
upon hydrolysis practically the same amounts of amid nito ...
were contained in the original humus solutions. The total
nitrogen contained in the humus, when calculated to the perco
of the total soil nitrogen, presents some variation, and on the at' :i
amounted to 16.80 per cent of the total soil nitrogen. When 4.1
data were calculated to the basis of the humus nitrogen it waa"i. .:
that the relative amounts of amid nitrogen contained increased .
a decrease in the humus nitrogen. In other words, relatively
amounts of amids occurred in soils which contain a low per~cs
humus nitrogen. This may be purely a coincidence, but is pr.
due to the fact that either in the preparation of the humus
or in the process of determining the amid nitrogen in it, a
amount of hydrolysis took place which would tend to mar
increase the relative amounts of amid obtained from those : h.g M
solutions containing the smallest amounts of nitrogen. Oa '*
average, 28.77 per cent of the humus nitrogen was found to be preset
as amids. It will be recalled that the amid nitrogen obtained u|po ,j
hydrolyzing the soils as a whole amounted to considerably sm.in,:..
percentages of the nitrogen dissolved.
S... .. iii i
BASIC NITROGEN.

The basic nitrogen bodies in humus were determined by the phos i'-:
photungstic acid method, as already outlined. The results are r*:
corded in the following table:


A1

..V






























relationship are even more marked. Soil No. 347, containing
":1pei cent humus nitrogen, yielded only 4.39 per cent of it as
itoeen, while soil No. 292, containing 0.058 per cent humus
n, yielded 44.83 per cent of it as basic nitrogen.
iew of the analytical error involved in the determination of the
a nitrogen, itjis unsafe to generalize concerning the relatively
Sincrease'in the basic nitrogen of humus in passing from soils
% large to soils of smaller humus nitrogen content. It seems
ibavble, however, that hydrolysis took place during the alkali ex-
....on process.
B.ri:' NONBASIO NITROGEN.
.ttis obviously not permissible to consider the difference between
total nitrogen in humus and the amounts of amid and basic
tgan that occur in the original humus solutions as nonbasic
en, for the reason that these solutions can not be considered as
been completely hydrolyzed. It is well known, for example,
.various proteins are quite soluble in alkalis without the proteins
ding any particular hydrolysis, as they can be precipitated,
more or less unaltered condition, from such solutions by the
n of acid. On the other hand, the nitrogen compounds in the
obtained from the humus precipitated by dilute hydrochloric
mi 1..:.



















: .... ..: ..: ......H
Per oent of nito-of h Per eof.a ntr i.oft ta ul
ofol. e nitrogen. gofi oil ""i.n .

347 .................. 0.196 62.22 25.32 0.249 68,78 l 2.17
428.................. .148 59.92 25.08 .213 : 370 i :. :
379.......... ....... .052 40.31 11.84 .203 75.1f 486.24.1
406 ........... ..... .063 53.84 27.87 .071 ;71..fi -.. i '
447.................. 055 52.88 25.58 ..061 64. 899 83
345................. .. 031 44.28 21.09 ..0335; s.o :: ,4
343.................. .027 39.13 21.26 ..035 57.37 27. 1 -.
405 .................. .046 68.65 37.39 .011 "SM : .1%
292............................. ........ ... .... .003 g. ....
Average..... ........... 52.9 25.05 ......... 64.8. 1.. ......0
Average----------------52,59 25.0564.4 u ...,

1 Not Included in averages. .

These data show the relatively large amounts of .non..ba"siI
contained in humus. On the average about 25 per cent oft
nitrogen occurred in the original humus solutions as nonbai...e
compounds, or 52.59 per cent when calculated to the pe6.
humus nitrogen soluble in dilute hydrochloric acid. The :shd
obtained upon hydrolyzing the humus precipitated by dilute: t L
chloric acid yielded a still greater amount of nonbasic :'tr'::1
On an average 64.84 per cent of this nitrogen occurred asno
which, when calculated to percentages of the total humus.
amounts to 31.98 per cent. By adding the nonbasic nitri
these two portions of humus it is found that 53.38 per cen"t f
humus nitrogen is made up of nonbasic nitrogen compoundtl"e.,i
referring to the data previously presented (p. 9) it will be seen .otsh
the relative amounts of nonbasic nitrogen in humus are so
less than the amounts of nonbasic nitrogen obtained in the
of the soil as a whole.
Considering the different groups of nitrogen compounds as 6b:
from the different portions of humus, the preceding data show
humus contained slightly less amid, basic, and nonbasic nitrogen.
were split off upon hydrolyzing the soil nitrogen as a whole, bigti"Y
the other hand, the humus nitrogen bodies as such are made UIE
relatively more amid and basic nitrogen than the soil nitrogen: s
whole. In other words, the nitrogen of soils soluble in 3 p'ere:
sodium hydrate is bound up in bodies differing somewhat from;ai
1." 7t' I~EE
'H++i*ii~















































eii ''i Iorrespuon g amounts m amn~oma souUons or numus,
iA be : osit the magnesium oxid distilation, there is brought
il cmparsno the nitrogen of these soils as found in both the sodium
Sate and ammonia solutions. The results are recorded in the
ing table:


.--- oal humus nitrogen


by different methods.


K..
lt*.R


-S^
AmM'


Percent
duetoyiL


Total
humus
oiniSO!!
solution
Per cent
of soil.


Total
humus
nitrogen
i am-
monia
solution.
Per cent
of soil


Nitrogen
absorbed
from am-
monia
solutions.
Per cent
of soil.


Soil No.


Amid
nitrogen
in NaOH
solution.
Per cent
of soil.


Total
humus
nitrogen
in NaOH
solution.
Per cent
of soil.


Total
humus
nitrogen
in am-
monia
solution.
Per cent
of soil.


Nitrogen
absorbed
from am-
monia
solutions,
Per cent
of soil.


...... ..... .
, L.: 0.100 0.774 0.657 0.502 345...... 0.025 0.147 0.140 0.08&
... .73 .590 .609 .758 343 ..... .020 .127 .117 .175
S.m. .050 .439 .284 .523 405...... .026 .087 .099 .139
... .039 .226 .179 .264 292...... .009 .058 .067 .079
..-.;: .083 .215 .218 .147


s.ome instances much higher percentages of nitrogen were found
l sodium hydrate solutions than in the ammonia solutions, and
iue instances this difference about equals the amid nitrogen con-

siniuiB g the nMtromgn ti the ammonia solutions of humus it was found advantageous to evaprate
b| two portion of the solution. In one the combined ammonia .only was determined, which
i;ie subtracted from the total nitrogen found in the other without distilling with MgO.


I. :!:::. :. .. ...
Iiii';iP 55 i;;Q i:.:,:"': 1 ;.;' l:s: :j';;;iiijjjL:11lll .jjjjjy:l'"~;. y, ;.


N::::
























wmcn is lost m tme metnous employed m me uterumianaon A I
humus nitrogen from ammonia solutions.
While the amounts of ammonia absorbed by the residues l.
evaporating to dryness ammonia solutions of humus bear n
relation to the amounts of humus nitrogen present, the abs
ammonia by humus took place to a considerable extent, a1. -
tion should be made for this in humus determinations, as
pointed out by Emery2 and others... .: ..,.*

PERCENTAGE OF NITROGEN IN HUMUS OF HAWATTl& -'lA

Hilgard has shown that humus from arid regions contains &
percentage of nitrogen than humus from humid sections. sqG*lo
that humus from arid regions contained on the average 15.2D |
cent nitrogen, while the humus from humid regions containei
4.23 per cent. In the work on soils at this station many humus.
humus nitrogen determinations have been made and some of t
results obtained are submitted in the following table;


Total humus and humus nitrogen in Hawaiian soils.


------i---------i-------_-----'- U ---
Humus. Humus. e
Humus. Humu us HumusS Humus e h
Soil :lo. Fer cent Eah. Per nitrogen. Soil No. Percent ash. Per
of so cent of Per cent cent of PfiS L
of soil. of soil.
soil of humus. of soil. soil. otal
______________ ____..:__:.____


347.................-
423 .................
379.................
406.........-........
447.-................
345...............
343...............
405................
292................
282............. ......
233 ......... .
284 ................
wt----!


14.81
14.31
8.20
3.08
3.61
1.74
2.45
1.74
1.80
2.77
1.78
2.72


2.28
3.89
1.91
1.64
1.54
1.13
1.73
1.07
1.87
1.04
.79
.70


5.16
4.12
5.35
7.33
5.94
6.88
5.21
4.91
3.21
7.87
6.40
5.62


285.................
236-................
237.................
288.................
312..................
313...............
314................
315................
316.........----......
317.......-.......
Average......


2.03
3.15
3.64
3.06
5.26
4.14
3.94
4.33
3.39
5.12


0.63
.94
1.38
1.48
1.19
1.44
1.17
.79
.81
1.18


h. .


rn-N


*5 8 /


These data show that the humus of Hawaiian soils contains nitrogen.
in amounts similar to those of humid soils elsewhere. Some of thKiI
soils used in this investigation (Nos. 379 and 447) came from sections ,i
which have been designated as arid, but the arid conditions whici,!
now prevail in these sections have probably.not existed as such fort.

I Loc. cit. 8ois. New York and London, 1907, pp. 136,137. v".;
SJour. Amer. Chem. Soc., 22 (1900), p. 285.


;;;II
;;i;
;""' ;;'


....i l


































age to 64.57 per cent of the soluble nitrogen.
3.) The relative percentages of amid and basic nitrogen, split off
t the hydrolys of Hawaiian soils, stand in the reverse order to that
hici h they occur in the vegetable proteins; while the percentage of
imbasic nitrogen practically equals that found in the vegetable pro-
as. It had been suggested that soil bacteria attack the nitrogen
l jW in such way as to split off the basic nitrogen compounds, and
t these then become ammonified, or otherwise lose their identity
: disamnino acid compounds, possibly being partially converted into
id forms.
(4 ~naerobic conditions predominate in Hawaiian soils, and under
conditions the nitrogen is more soluble than in well aerated soils,
the relative percentages of the different groups of organic nitrogen
pounds seemed not to be affected by the predominance of one or
ter of these conditions.
=0) The amount of nitrogen soluble in I per cent hydrochloric acid
O about twice as large as that of ammonia originally occurring in
basOils.


ernow












gen) remained insoluble after boiling in strong hydrohloriA
10 hours. Amids comprised 28.77 per cent of the humusi~ nito
which about one-half existed as amid in the original humus'siti
and which remained in solution upon acidifying with hydrohlo
The remaining half was split off when the humus, pre.ipitat
hydrochloric acid, was subjected to acid hydrolysis. The basi
gen ranged from 4.39 per cent to 44.83 -per cent of the hu musi
increasing as the total nitrogen of the humus decreased.
nitrogen was found to constitute 53.38 per cent of the humus
of which 25.05 per cent existed as such in the original humus soluti '
(7) The amounts of amid and basic nitrogen in humus expressed I
percentages of the humus nitrogen were found to be higher than the: i
amounts obtained by subjecting the original soil to hydrolysis .'
(8) In view of the large amounts of amid occurring in humus sobi,-c:l:,, l l
tions, it was found better to use sodium hydrate as the solvent .f i
extracting humus that is to be used for total humus nitrogen deter: ...
minations. -
(9) The humus of Hawaiian soils contains a small percentage fi': ....
nitrogen (5.88 per cent as an average of 22 samples), in which respe r
the humus of these soils closely resembles that found in humid soils
in the States.
O








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