University of Massachusetts - Amherst
ScholarWorks@UMass Amherst Masters Theses 1911 - February 2014
Dissertations and Theses
1917
The decomposition of organic matter in soils Fred G. Merkle University of Massachusetts Amherst
Follow this and additional works at: http://scholarworks.umass.edu/theses Merkle, Fred G., "The decomposition of organic matter in soils" (). Masters Theses 1911 - February 2014. Paper 1235. http://scholarworks.umass.edu/theses/1235 This Open Access is brought to you for free and open access by the Dissertations and Theses at ScholarWorks@UMass Amherst. It has been accepted for inclusion in Masters Theses 1911 - February 2014 by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact
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the;
decomposition op organic matter in soils
by-
Fred
G.
Merkle
"Thesis submitted for the degree of M. Sc. H
Massachusetts Agricultural College
Amherst
June
1917
LIBRARY
MASSACH^ET TS AMHERST, MASS.
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ii
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i
h
i
.in
n ii
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wr in
;/.a'j.tjcr mOHgA;;i3 )
NaHC0 3
+
NaCl.
The amount of acid needed to make this change need not be known, nor is it necessary to know the normality of the
alkali used, (42) Hei3set, Compte. Rendu. Vol. 38, p. 1001 and Vol. 90, p. 1144 (43) Brown and Escomb, Proc. Roy. Soc. 76 (1905) p. 29.
/
-17-
Methyl orange 13 now added and till the neutral point is reached.
^
HC1 run in drop by drop
The exact amount is
recorded and is equivalent to the COg contained.
NaHG0 3 + HC1
«
mo.
~$
One cubic centimeter of
NaCl + HgO + COg.
E HC1 equals 4.4 milligrams of
C0 2 .
Cochineal gives about the same results as methyl orange, but the latter was used throughout this work.
;
;
-13-
EXPERIMENT
I
LEGUME FODDERS The plants were cut off at the surface of the ground when in full bloom or as near that stage as possible. dried, slowly at first and later in the oven.
They were
When dry they
were ground and reground until all the material would pass
through a 2 mm. sieve.
Fifteen grams were mixed with 300
grams of moist loam, placed in the inoculation bottles on top of a layer of gravel and slightly compacted.
The bottles
were stoppered and the outlet tubes closed with glass plugs.
They were allowed to incubate in the dark at room temperature, the CO2 produced being measured weekly (usually) in the manner
jU3t described.
An untreated soil served a3 a check for all
the following experiments.
TABLE
MILLIGRAMS C0 2 PRODUCED
I
:Loam 300 gr. ;Loam 300 gr. ;Loam ioo" gr.:Loara 300 gr. + soy bean + red clover + alfalfa ;
Date
;
;
Untreated Nov. Nov. Nov. Dec. Dec. Dec. Dec. Jan. Jan. Jan. Feb.
15 22 29
I:
::
::
6
13 21 23 10 17 23
TOTALS
6
:
,
I
:
;:
:;
:!
:;
35.2 33.0 50.0 52.0 37.4 43.4 50.5 41.8 37.4 28.6 35.2 449.6
;:
15 gr. :
:
:!
:
i
:
::
:
:
,:
fodder
475.2 385.0 211.0 213.4 167.4 206.8 237.6 191.4 195.8 167.2 160.6 2611.4
fodder 15
:" :
:
;
:
:
:
;
:
;
:
g,T.
444,4 336.6 242.0 281.6 200.2 228.3 193.6 139.2 167.2 158.4 165.0 2607.0
:
:
;
:
:
:;
:
:
;
;
::
;
!:
fodder 15 gr.
426.8 325.6 154.4 195.8 132.6 206.3 162.8 132.0 143.0 162.0 169.4 2220.8
-19The above figures are plotted in Chart I.
They show
that a rapid production of CO2 takes place the first two
weeks after a legume fodder starts to decay, and that after the second week they settle down to a steady rate of decom-
position.
Apparently red clover decays a little slower than
the other fodders,
but there is no great difference between
them.
There are possibilities of errors in the aspiration of the gas, but the irregularities in the curves are due to
these.
Temperature changes affect all alike, hence the
general tendency is for all to rise and fall at the same period, though not always in the same degree.
The uni-
formity of the check indicates the accuracy of the method.
Duplicates were run in the early part of the experiment but the close agreement seemed to justify dropping them to save
work.
HTJMU3
PRODUCTION
Equally important as the rate of oxidation is the humus produced.
A substance may oxidize very rapidly, as for
example sugars, and still not increase the humus content
noticeably.
Such substances would be of questionable value
as regards the physical improvement of the soil.
Unpublished
workv 4 ^) shows that sugars break up very rapidly in the soil
and are nearly completely oxidized within a week or two. Lactose, maltose, saccarose, dextrose and fructose run about the same.
Sugar beets (Chart II ) in the early stages
of decay show the effect of their sugar, but later gave about the same results as the rape and swedes. (44) Writer 1 s.
-20The materials used in the COp production experiments,
having been allowed to incubate from November 8th to February 19th, were removed, dried and their humus content determined
by the official method.
The results are recorded together with
the total COg production for comparison.
HUMUS PRODUCTION
TABLE II
Humus, per cent No treatment
Soil » * w
+ + +
Alfalfa Red clover Soy beana
i*»^
5g mS^B^m
^mtmmim+mwM^mmmMy^mt-^m-mmmmwmmmmwmMmm^atmMmwm^mmmmmMmwesmm^
^mrnhm ^i
Total C02 - Cg,
2.96 % 3.43 H 3.29 3.285"
44 260 220 261
•»
Cg. H II
N
The figures indicate that there is little choice between the legumes in decay and huraification.
EXPERIMENT II ROOT CROPS AND RAPE These substances were used to compare readily decomposable carbohydrates, as found in plants, with more inert
materials.
For this purpose sugar beet roots, swede or
rutabaga roots and rape tops were used.
All of these contain
some form of stored food, sugar or starch.
The plants were
taken from the field, air dried, then oven dried, and ground fine enough to pass a 2 mm. sieve.
Fifteen grams of each were
mixed with 200 grams of moist soil and placed in incubation bottles as previously described.
Determinations of COg produced were made weekly.
j
;
-21-
MILLIGRAMS co 2 produced :Loam 300 gr. :Loam 300 gr. Loam 300 gr. Loam 300 gr. r rape + sugar + swedes beets Untreated 15 gr. 15 gr. 15 gr.
TABLE III
•
;
:
Date
;
;
;
;
Nov. Nov. Nov. Dec. Dec. Dec. Dec. Jan. Jan. Jan. Feb.
15 22 29
!
::
,:
6
::
13 21 28 14 17 28
::
:
,:
::
::
;:
6
,
TOTALS
:
,:
35.2 33.0 50.0 52.0 37.4 48.4 50.6 41.8 37.4 28.6 35.2 449.6
;
550.0 708.4 213.4 235.3 171.6 132.0 160.0 125.4 103.4 118.3 106.3
;
2625.6
i!
:
:
:
::
:
;:
::
;
:;
!
:
::
:
;
;:
::
:
;
:
!
464.2 484.0 261.8 226.6 162.8 189.2 165.0 147.4 132.0 114.4 140.8
2488.2
:
400.4 396.0 231.0 244.2 165.0 206.8 182.6 158.4 110.0 149.6 156.2
!
2400.2
j!
;;
:
::
;
:
:
:
:
:
Sugar beets, Chart II, as might be expected, show rapid
decay at the start but the sugar is all oxidized in two weeks, after which time the organic matter in them is no more decom-
posable than that of other materials.
Rutabagas contain but
little sugar and decay no faster than legume fodders.
Rape
is slowest at first but as time goes on it exceeds the others.
Comparing the legumes with roots we find that the former are more readily oxidized as time goes on, that is, after the
sugar in the roots is broken down.
HUMUS PRODUCTION The results of the humus determination are as follows:
TABLE IV
rS-SK
Humus, per cent Soil H
" H
No treatment + + +
Swedes Sugar beets Rape
2.96 % 3.56 " 3.28 » 3.24 M
Total C02
Cg.
-
44 243
Cg.
262 240
M
N
H
r
Aoq^o-y
3W
k
•A
I
V
-22The difference as shown by the humus figures seems the
more representative, since the higher C0 production for 2 sugar beets is due to the sugar . Rape falls in third place in both instances*
EXPERIMENT III
LITTERS The materials listed below find their way into the soil
through natural agencies or as litters and were selected with the expectation of obtaining large differences.
It was
thought that pine needles might even lower the bacterial activity, at least for a time.
Pine needles, oak leaves and maple leaves were picked while still green, air dried and later oven dried.
White
pine shavings, as used for litter, were oven dried.
substance was ground and sieved.
Each
Fifteen grams were used in
each case. TABLE V
Loam :
;
300 gr.
\
[Untreated 15 22 29 6
13 21 28 10 1? 28
TOTALS
6
!
!
:
,
:
,:
::
:
!
::
::
;:
::
',
:
35.2 33.0 50.0 52.0 37.4 48.4 50.4 41.3 37.4 28.6 35.2 449.6
:
!
::
:
:
:
;;
:
;
:
j
;
:
1
:
Loam
300 gr.+ 300 gr.+ Shavings Maple leaves :0ak leaves :Pine need.
:300 gr 9 +
Date Nov. Nov. Nov. Dec. Dec. Dec. Dec. Jan. Jan. Jan. Feb.
MILLIGRAMS C0 2 PRODUCED Loam Loam Loam 300 gr.+
;
15 gr.
:
:
;
15 gr.
257.4 257.4 118.3 156.2 103.4 88.0 105.6 101.2 77.0 132.0 74.3
1471.8
:
:
;
:
:
:
;
;:
:
:;
:
:
;
275.6 250.3 224.4 211.2 206.3 184.3 167.2 171.6 149.6 143.0 160.6
:
:
;
:
;;
;
::
::
:
tmmmmmiSmmmmd
15 gr.
338.3 303.6 182.6 178.2 187.0 180.4 162.8 147.4 158.4 149.6 116.6
2105.4
15 gr. i
I
;
:;
:
::
;
:
:
!
343,2 259.6 224.4 167.2 193.1 184.3 178.2 151.3 136.4 134.2 110.0 2083.4
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-23See Chart III.
White pine shavings stand out as a striking example of an inert substance, being lowest and slowest in C0£ production.
Maple leaves give a more uniform decline than anything else. The litters in general, as might be expected, are not as rapidly decomposed as either legumes or root crops and suggest the importance of nitrogen as an aid to oxidation, as those
materials which are low in nitrogen are slow to oxidize.
This
latter statement applies to the later stages of decomposition.
HUMUS PRODUCTION TABLE VI Humus, per cent No treatment
Soil M
» H
2.96 % 3.345 3.18 H 3.07 " 2.91
Maple leaves + Oak leaves + Pine needles + Shavings +
tt
Total CO2 44 214 210 208 147
-
Cg. Cg. N H
H II
The rate of oxidation, as measured by humus production
and CO2 production, follow the same order; namely, (1) maple leaves,
(2) oak leaves,
(3) pine needles,
(4) pine shavings.
It should be noted that the shavings after having been in the
soil for three or four months did not increase the per cent
of humus, in fact, lowered it slightly.
EXPERIMENT IV CEREALS AND BUCKWHAT Barley, oats and buckwheat were used because good samples of them were available.
Barley and buckwheat are quite
;
:
-24-
frequently plowed under as green manure crops, which is not
Plants that were half matured were dried,
true of oats.
ground and mixed with the moist loam.
The rate of oxidation
was as follows:
TABLE VII
MILLIGRAMS CO2 PRODUCED Loam 300 gr. Loam 3(76 gf, Loam 300 gr» ,Loam 300 gr. + Oats + Buckwheat + Barley Untreated 15 £r. 15 gr. 15 gr. ;
Date
;
;
::
;
Nov. Nov. Nov. Dec. Dec. Dec. Dec. Jan, Jan. Jan. Feb.
15
22 29 6
13 21 28 10 17 28 6
TOTALS
;' :
:
;:
;:
::
;!
;;
;:
,;
;i
;;
:
35.2 33.0 50.0 52.0 37.4 48.4 50.6 41.8 37.4 28.6 35.2
449.6
:
:
:
:
:
:
;
::
:
!
;
::
::
349.8 338.8 242.0 239.8 176.0 253.0 184.8 189.2 176.0 184.8 147.4
2481.6
:
442.2 283.8 176.0 182.6 184.8 133.6 125.4 162.8 160.6 158.4 136.4
;
2151.6
;
:
j
.
;:
::
:
1:
;:
:
;
f/28.8
:
:
380.6 341.0 281.6 191.4 195.3 176.0 138.6 134.2 118.8 123.0
!
2529.2
;;
;:
;
::
;
:
;
;
;
See Chart IV
Little or no consistent variation occurs.
Buckwheat
appears to be the most inert.
HUMUS PRODUCTION TABLE VIII
—WW
flipinf
mim
Humus, per cent Soil H H »
No treatment + Oat fodder + Barley fodder + Buckwheat fodder
2.96 % 3.185 » 3.10 " 2.99 •
Tota l CO2 44 248 252 208
*
Cg .
Cg, H H M
Oats and barley are very nearly the same, the variation
being within the limits of error. Buckwheat seems to be a very inert substance, increasing the per cent of humus almost
UNTVEteSAL CRO^S SECTION
5
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PAPB^ .i
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