PBOCs'J)IN08 ot
2'1i~
OKLAHOMA
••••
THE TOTAL NITROGEN, PHOSPHORUS AND
CALCIUM CONTENT OF COMMON WEEDS
AND NATIVE GRASSES IN OKLAHOMA·
By H. J. Harper. H. A. Daniel. and H. F. 'Murphy"
Oklahoma A. and M. College
Information concerning the chemical composition of natural vegetation 1a very llmited as compared with the total number of plants which
have been studied. and the major pOrtton of the investigations which have
been conducted have been confined to weeds and grasses which grow in
competition with cUltivated crops.
IDee (6) determined the amount of nitrogen in thirteen common
weeda which occurred in the cUltivated fields of North Dakota and found
~ twenty-four out of the twenty-seven weeds which were analyzed contained larpr amounts of n1tl'Olen and phosphorus than wheat. oats. barley.
and flax. The averaae nitrogen content of these weeds was 2.53 per cent
and the pboepborus content was .29 per cent.
8D1der (11) analyzed fifteen different weeds for nitrogen and found
tbM on the avenae they contained 3.01 per cent of this element. Portulaca c1eraceae contained the J&raest amount of nitl'Olen. which was 4.40
per cent. ~der suaests that weeds are not deUca.te feeders because of
tile la.rae amount of mineral matter which they contain and when they
are bUrned a heavy 1088 of nitrogen occurs.
PlcItel1 (10) determined the protein content of nine Florida. weeds and
'OUlad &bat mM of the plants were relatively low in nltropn as compared
• ODnVlbuUon tram the Oklaboma Asr1cultural Bzperlment Statton•
•• on.e auUlon wIIb to tbaDk Robert 8va\ton and B. I. Peatherly. of the Bot-
ACADBMY OF SCIBNCE FOR. 1933
aT
. &IQ' Department of the Oklaboma A. and K. 00l1ep. for ....tance in the 1dentUlcatton Of Ute plants studied.
with the results secured by the two previous inveatigators; although Portulaca cleraceae contained •.05 per cent nitrogen, which 18 s1m1lar to the
result secured by Snyder (11).
.
campbell (2) studied the nitrogen content in the tops of eleven winter
annuals which were secured in the fan and again in the spring. He found
that the spring growth contained on t·he average 3.53 per cent nitrogen as
compared with 2.63 per cent which occurred in the leaves and stems which
grew in the fall. A comparison of 'the nitrogen content of nine annual
plants at different stages of growth indicated that a rapid decrease in
nitrogen content occurs between the blooming period and maturity. Just
what effect the loss of leaves had on these results was not discussed. Six
weeds growing in rye contained about the same amount ot nitrogen as the
rye plants when harvested at different periods during the growing season.
The roots of certain weeds contained smaller amounts of nitrogen than
the leaves, and' the stems were usually higher in plant food than the roots.
M'illspaugh (8) analyzed forty-nine different plants for total nitrogen,
phosphorus, and potassium, and his results indicate that the composition
of weeds and grass are very similar to that of CUltivated crops although
a marked variation occurs in certain species.
Cooper (3) found that the nitrogen, phosphorus, and calcium contents
of Poa praetensis, Danthonia spicata, and Andropogon virgintcus were all
low when these plants were in full bloom. Cruickshank (4) and others have
shown that the nitrogen and phosphorus content of grass decreases as the
season advances and that young grass is high in nitrogen.
Stutzer and Seidler (12) analyzed seven important weeds for nitrogen,
phosphorus, potassium. sodium, and calcium. These weeds contained larger
amounts of plant food than ordinary field crops, and in some instances '
plants which contained large amounts ot calcium were low in potassium.
Kling (6) has made a survey of the German literature on the chemical composition of weeds and reported the analyses at six common weeds,
all of which were very high in plant food. The average nitrogen content
was 3.64 per cent; phosphorus, .52 per cent; calcium, 2.35 per cent; and
potassium, 6.20 per cent. These analyses were much higher than thOlSe
secured by Stutzer and Seidler (12) on the same kind of plants.
Korsmo (7) pUblished a table in his book on the tood value contentt
of ftfty-three different weeds. The average nitrogen content was 2.47
per cent; phosphorus, .33 per cent; pOtassium, 3.29 per cent; and calcium,
1.79 per cent. A greater variation occurred in the potassium content of
the different plants than in case of calcium. These analyses point out
very clearly that many weeds remove large amounts of plant tood from
the soil.
Nielson (9) and Brenchley (1) have classified a large number of weeds
on the basts of their development on soils ot varying degree of acidity and
texture but did not study the etfect ot so11 conditions on the composition
of different plants.
White (13) studied the growth of Rumex acetosella on limed and unlimed soils and found that this plant responded to an application of limestone; however, the stimulating effect ot lime on the growth of red clover
resulted in the choking out of the red sorrel due to plant competition.
EXPERIMENTAL
Erosion of cultivated soils combined with a shallow zone of organic
IDatter accumulation in the sol1 profile under virgin conditions has reSUlted in the production of large areas of marginal land in Oklahoma. The
ftrat type of vegetation which develops on abandoned areas are annual
weeda and Il'&SSe8 typical of those plants which were most abundant in
--
PROCEEDINGS OF THE OKLAHOIIA
tile fteIdI or along tile borders or in fence rows whUe the land was in
crops.
In many areas the change from the annual weed stage to the peren.
Dial weed stage and from the perennial weed stage to the mixed weeds and
IP'US stale OCCUJ'I very 8lowly. The fertility 'of the soU Is one Important
factor whieb Umlts the rapid development of climax grasses in many areas
and the ablence of seed in the soli retards the appearance of those grasses
wbere condltlons are favorable for their development.
Due to dlfferences in cllmatic and soU condltions, many weeds which
appear in one part of Oklahoma are not abundant in other areas. Bome
species, bowever, are adapted to a wide range of condltions and may be
found in both dry and molat climates. During the season of 1927 a few
of the common weeds which appear on abandoned land. in waste places,
and following the harvest of small grain were collected and analyzed. The
results of these analyses are given in Table I.
In all cues the plants had reached the blooming stage and do not
represent an Immature condition. Many of the plants contained more
than 2 per cent of nitrogen, which 18 similar to the amount of this particular element which occurs in cultivated legumes. The phosphorus content of these plants was exceptionally high on the average even in case
of plants which were growing on relatively poor soil, such as Erigeron
canaclens1a, which is a weed commonly found on sandy land. The calcium content of all the weeds was high as compared with the calcium
content of native grasses.
SOU condltions and the ratio of stems to leaves in the different species
of plants are important factors in affecting the nitrogen content of the
plants. Coreopsis tinctoria has a small proportion of leaves as compared
with the stems and 18 low in nitrogen. The effect of soil on the nitrogen
content of weeds is shown in case of Ambrosia artemlsUfol1a (Sample No.2,
Table I) and ErIgeron canadensis (Sample No. 14, Table I> which grew
on a very poor sandy sol1, and the plants were much lower in nitrogen
than I1m1lar species grown on different 8011.
In order to obtain further information on this particular subject, R.
large number of plants were collected in December, 1932. Most of the
leaves had dropped before the plants were collected; consequently the
analyses represent chiefiy the plant food content of the stems. These
anab8e8 are given in Table n. In most cases the phosphorus content of
the Items was very much lower than that which occurred in the first
group of plants which were analyzed. Also there was a marked decrease
In the nttropn and calcium content which did not occur due to leachIn&' or maturity but is due to the fact that the nitrogen and calcium content of the leaves is much higher than in the stems.
The lowest results occurred in case of Aristida oligantha., which 18
one of the ftrst plants to appear on poor eroded land. This particular
plant is exceed1nlly low in nitrogen, phosphorus, and calcium .during all
of Ita I1'Owth stages; however on good soil it wUl absorb considerably larger
amounts of plant food than will be found in the plants produced under
unfavorable .condltions. This plant is easUy carried by the wind and
In the ablence of competition from other plants it can secure a foothold
In waste areas and survive under very unfavorable conditions.
Bermuda I1'88S was much higher in nitrogen. phosphorus, and calcium during the dlfferent growth stages than most of the other grasses
atucUec:l. '1bI8 Ja an important factor in localities where a mineral deficiency
In the foraae may affect the Irowtb of livestock.
; III order to 88Cure more complete information on the composition of
the ~ different tlnds of weeds which make up the major portion of
tbe Datift veaetatton In meadows, along roe.dsldes and in cultivated 1leldl
-=
....
tl')
tl')
0.-
a=
~
IliQ
~
~
~
~
~
~
~"ill
COmmon Name
Location
.426
.IM
.288
.286
.218
.180
.282
.150
.15&
.130
.2M
.301
.381
1.060
.SMS
1.080
1.700
1.1150
2.881
:180
2.280
.SA
PJlROBNT
PhC)8. calCIum
.ssa
2.120
.228
.258
.322
.301
.258
.219
.180
.307
.3oiS
.1M
.300
.dB
••
.775
1.101
.975
1.151
2.881
1._
1.&80
.338
.801
.691
3.022
I._
1.7M
1.518
2.8eO
l.eal
1.517
.'198
1.802
2.222
1.139
1.13'
1.888
1.320
1.785
2.000
0.913
1.071
2.085
.2H
.211
••
1.188
1.&38
2.023
1.393
1.882
2.225
2.M5
2.310
1.133
2.112
1.880
.932
1.878
2.189
2.300
Nltl'ogen
TABLE I.
'!be Nitrogen. Calcium. and Phosphorus Content of Mature Weeds and Grass Collected in Oklahoma in 192'l.
No. SClentUlc Name
,.
8 m1. E. of Enid
11 m1. S. E. of Glencoe
Exp. Sta. Parm. St11lwater
A. <& M. Campus. Stlllwater
11 m1. S. W. of StUlwater
East of Buffalo
1 mi. N. of Okeene
1 m1. N. of carrier
5 m1. S. of St11lwater
11 m1. S. W. of St11lwater
Exp. St&. Parm. Stillwater
11 m1. S. E. of Glencoe
4 m1. W. of Quinlan
East of Buttalo
S. E. of Chandler
1 m1. N. of Carrier
5 m1. S. of St11lwater
Exp. St&. Farm. Stlllwater
5 mi. S. E. of St1l1water
East of Buffalo
Near Goodwell
Exp. St&. Farm. St1l1water
S. E. of Chandler
501 Monroe St.• St11lwater
Exp. St&. Farm.. St1llwater
A. & M. Campus. Stillwater
U m1. N. E. of Carrier
8 mi. E. of Enid.
1 Acn1da tamar1lclDa
2 Ambrosfa artem18t1tol1&
8 Ambroet.a a:rtemJa1Uolla
AmbJ'Olda pel10stachya
6 Ambrosla psUost&chya
e Applopappus clltatua
1 Applopappus clltatua
8 Applopappua cll1atua
0 Applopappus clltatus
10 Buch10e dactyloldee
11 Coreopala tlnctorla
12 Coreopsls t1netorta
18 Cynodon dactylon
Water hemp
Annual Ragweed
Annual Ragweed
Perennial ragweed
Perennial ragweed
Rosin weed
Rosin weed
Rosin weed
Rosin weed.
Buffalo grass
Wild Flax
WUd Flax
Bermuda gra.ss,
(seed stage)
Muletall
MUletall
Muletall
Muletall
Muletall
Muletall
Muletall
Wild sunflower
Wild lettuce
Wild lettuce
Sweet clover
Blaekeyed SUsan
Crabgrass
Crabgrass
Cocklebur
I" ErIgeron canadena1s
1& Erigeron canadens18
18 Brtgeron canadensls
17 Ertgeron can.adenall
18 Erigeron canadena1s
19 Brlgeron canadena1s
20 Bngeron canadensll
21 Heltanthus annuua
22 Laetuea ecartola
28 Lactuca acar10la
:lot Mel110tua alba
25 Rudbeot1a hJrta
28 Syntherlsma sangulna118
2'1 Syntber1sma aangulnalll
28 Xantblum commune
- TABLB II.
Amanmthua~
28
M
commune
commune
commune
commune
commune
Oynodon dactylon
Hellanthua an:nuUl
Bellanthua annuua
Hellanthua annuua
8alsola 011
8permacoce glabra
8ynther1sma aangulnalls
8ynthertema aangulnalla
XAnthium
Xanthium
X&nthlum
21 Xanthlum
28 Xanthium
n
1"
11
18
17
18
18
20
21
18 Cynodon dactylon
11 croton capltatua
12 croton capltatua
..
.,
"
Ampb1achyrla dracuDdu101da
a Ampblachyrla dracuDduJoidee
AndropQlOD 8OI'ghum
1 Andropocon 8OI'Bbum
e Applopappua cJ11atua
Arpmone 1ntermec:Ua
8 Ar18tida ollpntha
Ar1atlda Ollpntha
10 Ar1atlda ol1pntba
1
2
Ifo. 8cleDutic Rame
Cocklebur
Cocklebur
Cocklebur
Cocklebur
Cocklebur
stems
leaves
stema
stems
seed
3 ml. N. E. of Guthrie
3 ml. N. E. of Guthrie
2 mi. E. of Glencoe
4A mi. S. of StUlwater
1 ml. N. E. of Coyle
1 mi. N. E. of Coyle
7 mi. W. of Y'ale (eroded land)
2 mi. S. at 8t1llwater
7i mi. 8. at 8t1llwater
7A ml. 8. at 8tWwater
2 mi. 8. of 8t1llwater
1 mi. N. E. of Coyle
2 mi. S. of 8tlllwater
7 ml. W. of Yale (eroded land)
7 mi. W. of Yale
(Virgin prairie puture)
7i mi. 8. of 8tlllwater
3 ml. N. B. of Guthrie
5 mi. N. W. of Perklna
2 mi. W. of StUlwater
3 mi. N. Eo of Guthrie
4A ml. S. of 8tUlwater
2 mi. S. of StUlwater
1 mi. N. B. of Coyle
4A m1. S. of StUlwater
7i mi. 8. of StUlwater
4 mi. N. W. of Perklna
Tumble weed.
Broomweed
Broomweed
8umac cane (old)
8umac cane (new)
Rosin weed
Prickly poppy
Triple awned grass
Triple awned grass
Triple awned grUlt
Goat weed
Goat weed
Bermuda graaa
Bermuda graaa
Wlld sun!1ower
Wlld sun!1ower
WUd sun!1ower
Russian thistle
Rough button weed
Crab gra8IJ
Crab graM
Location
~
Common Name
of the Leaves Bad Pallen.
.-
.298
.329
1.180
.491
.980
1.200
1.120
.398
.3'70
.391
.710
.W
.170
.680
1.090
.t68
1.080
.685
.321
.830
1.200
.378
.284
.208
.'700
Nltr'p
~al1
.41'
.049
.081
.031
.012
.081
.104
.117
.17'
.032
.031
.028
.089
.063
.088
.078
.018
.CKa
.071
.031
.011
.011
.OM
.085
.OM
.0&5
E
~
0
2.20
4.460
1.740
1.218
~
~~
=
S!
~f4
~
8
•
...
1.010
1.201
.2H
.302
.821
.990
1.110
.toI
.318
1.'''0
.NO
.211
.110
.182
1.MO
.2U
l.8tO
.us
1.101
1.011
.8'rI
PDoamn'
PhOll. Oalolum.
lfttroIen, PboIpborus, aDd caJclum Content of Stems of Mature 1'taDta CoUected In DeceDiber 21, 1832.
...
•
~
0.
...'"
0
~
lilt
~
fIQ
t3
fIJ
~
~
~
~
~
Common Name
Location
.............................
N1tr'gn
2.286
3.600
2.300
2.850
2.340
2.261
2.060
1.804
.910
1.280
2.120
2.020
2.040
2.240
2.826
1.804
1.400
1.900
2.690
1.950
2.165
2.605
2.858
1.800
2.766
1.850
1.640
1.150
1.280
1.045
1.585
2.640
.890
3.795
2.300
2.010
2.010
1.740
UNS
3.410
1.105
3.280
.274
.190
.180
.190
.098
.185
.075
.1M
.091
.147
.075
.625
.182
.138
.128
.185
.200
.210
.085
.280
2.440'
2.291 .
lUOO'"
1.550'
1.610·
1.8851.27&
.925
1.090"
2.370'
1,'790>
1.286·
1.460"
.'720'
2.420'
1.548
.970
.985
1.560
.370
.840
1.500
1.725
1.400'
.878'·
1.880'
1.880'
1.:180
Phoe. Cilctum
.aM
MO
.341
2.110
.121
1.100
ur,o
.075
.330
1.810
.1M
2.501
.216
3.3&0
.252
:UOO
.127
.380
.105
.90&
.169
1.820
.089
1.250
.U9
1.ll&.093
1.1~
•US5
.262
.065
.101
.200
.146
.212
.212
PBRCBNT
Table In-N1trogen. phoephorua, and caIc1um content of weeds and grass collected during June, 1933, near Stillwater, Oklahoma. In moet C&ae8 the plante were blOODl1Dg and represet1t a rnaxtm:um. growth stap.
.
No. BctentUtc Name
,
.............................
.........................
Common yarrow
Pigweed
Pigweed
Pigweed
Common ragweed
Common ragweed
PerennJal ragweed
Horseweed
Johnson grass
Dogbane
Rosin weed
False Indigo
Lamb's quarter
Plr;:eed
81 ver thlatle
Bindweed
20
Hel1anth~tlolar1s
Ambrosia
Ida
Andropogon sorghum
Apocynum hyperlc1follum
ApPIO~ c1llatus
Bapt18la
cteata
Chenopocl1um album
Chenopodium leptophyllum
C1rc1um cana.scene
ConvolvuJua arveD818
Deamodlum aeaa1llfolium
Deenonthua illlnoewse
D10dla teres
Dlodla teres
Erigeron canadena1a
Buflhorb1a ffexagona
He lanthus annuus
1 Ach1IIea mlllefolium
2 Amannthus hy1)rldus
8 AJnan,nthus retronexus
Amamnthus retroflexus
6 Ambroe1a artem1s11tolla
6 Ambrosia artemJa11folla
7 Ambrosla ~08tachya
8
I
10
11
12
18
14
15
16
17
18
19
21
22
23
H
_
Button weed
Button weed
MuletaU
Hexagonal spurge
WUd sunflower
Wild sunflower
Wlld ~tato vine
Wl1d ettuce
Evening rcrimrose
Prairie cover
Plantain
Bmartweed
Smartweecl
Knotweed
Purslane
Wlld alfalfa
Wlld alfalfa
Wlld alfalfa
Curled dock
Horse nettle
Buffalo bur
Iron weed
Cockle bur
S m1. S. E. of 8tUlwater
«I m1. S. E. ot StUlwater
8 mi. S. B. of 8tlllwater
Exp. Sta. Farm, StUlwater
Exp. Sta. Farm. Stlllwater
Exp. 8ta. Farm. Stlllwatez'
11 m1. 8. B. of 8t111water
Exp. 8ta. Farm. StUlwater
Exp. 8ta. Farm, St1Uwater
8i mi. 8. B. of Stlllwater
Exp. 8ta. Farm. SUllwater
3 m1. 8. E. of 8tWwater
Exp. 8ta. Farm. St1Uwater
3 mt. So B. of St1llwater
Exp. Sta. Farm. St1Uwater
Exp. 8ta. Farm. St1Uwater
Exp. 8ta. Farm. 8tillwater
Exp. 8ta. Farm. St1Uwater
3 mi. 8. E. of 8tWwater
3 mi. 8. E. of StWwater
Exp. 8ta. Farm. 8t1llwater
86 mL 8. of 8tUlwater
Exp. 8ta. Farm. Stillwater
86 mt. S. of Stillwater
Exp. 8ta. Farm. St1llwater
81 m1. S. E. of StUlwater
Exp. Sta. Farm. 8tUlwater
Exp. Sta. Farm. StUlwater
3 mi. S. E. ot St1llwater
Exp. Sta. Farm. Stillwater
3 mi. S. E. of StUlwater
81 m1. S. E. of 8t1llwater
Exp. Sta. Farm. StUlwater
Exp. 8ta. Farm. Sttllwater
S mi. 8. E. of 8t1llwater
Exp. 8ta. Farm. Stillwater
2 mt. W. of StUlwater
3 mi. 8. of Claremore
4 mi. 8. E. of Stillwater
Exp. Sta. Farm. Stulwater
Exp. 8ta. Farm. Sttllwater
Exp. 8ta. Parm. 8t1llwater
25 Ipomea p
urata
26 Iiectuca ecartola
27 Leepedeza v1rglnlca
28 Oenothera lactnlata
29 Petalostemum purpuerewn
30 Plantago PurBhll
31 Polygonum hydropiperoldes
Polygonum penney'lvaD4cum
Polygonum ramoe1M1mum
Portulaca oleraceae
Psoralea pedunculata
Peoralea peduncu1ata
Peoralea pedunculata
Rumex crlapua
Solanum carol1neD8e
Solanum roetTatum
Vernonia. ........._......
Jtanthlum commune
42
32
8S
34
86
36
87
38
81
40
'1
PROCEEDINGS
0' THB
OKLAHOMA
ano&ber IeI'Ies of plante were collected In June. 1933. The results of
tbeIe ana1JIes are liven In Table m.
MOlt ot these plants contained more than 2 per cent of nitrogen.
ThOle which contained more than 3 per cent of nitrogen were not as mature as the average plants which were collected. This Includes Amaranthus, byrtdua. Portulaca oleraceae. Solanum carollnense. and SOlanum
roetratum. Many of these plants studied commonly occur in areas ot
pralrfe and although they are objectionable trom the standpoint of the
quality ot hay produced. it is very evident that some of these plants are
hllher In phosphorus and calcium content than the prairie grasses. The
presence ot these weeds in the hay would increase the total mineral content of the forage and under many conditions this effect woUld improve
rather than injure its feeding value.
It has been suggested by certain investigators that livestock graze on
those areas where the plants are high in ash. In some instances this is
true: however, sheep which feed heavily on weeds will eat the common
rae weed (Ambrosia artemisUfolla) and the perennial rag weed (Ambrosia
pe11ostacbya): however they do not eat common yarrow (AchUlea mUllefolium) . Consequently the presence of organic substances which affect
the palatab1l1ty of vegetation is undoubtedly an important factor trom the
standpoint of the commercial utlllzation of green plants for grazing
purposes.
The effect of weeds and grasses on the conservation of plant foods
in uncultivated fields and during periods when crops are not in an active
II'Owing condition is important under many conditions. Most weeds are
high in nitrogen and decay more rapidly than residues from com. kaftr.
and small grain. The effect of the concentration of large amounts of
ash at the surface of the soil is an important factor in affecting nonsymbiotic tlxatlon of nitrogen which is one of the important processes by
which abandoned land becomes more productive after a few crops of weeds
have been grown and the residues accumulate in the surface soil. Perennial
rae weed, rosin weed, wild sunflower. muletall. and cocklebur are some of
the more vigorous plants appearing on eroded land. All of these plants
contain much larger amounts of calcium and phosphorus than the native
rraasea and the continued growth of these plants on abondoned land
produces a marked infiuence on the availability of mineral matter in the
sol1. Th18 condition also produces a stimulating effect on the development
of arasses when they begin to appear.
In order to compare the composition of weeds with the composition of
native grasses, the results of a large number of analyses which have been
made by H. A. Daniel on plants collected over a period of years are
given in Table IV.
Grasses are as a rule low in nitrogen, phosphorus. and calcium.
However, Agroetis alba. Cynodon dactylon. Paspalum dialatatum. Buchloe
dactyloides, and Syntherlsma sangu1nalis are all fairly high in phosphorus
content as compared with the other grasses. The calcium content of
arauea Is low: although BermUda grass is much higher than the average
and DaW8 Iras& is exceedingly low in this particular element.
SUMMARY
A study of the nitrogen, phosphorus. and calcium content of common
weeds and native grasses growing in Oklahoma was made.
Two hundred and twenty-nine composite samples were collected and
~ . Tbls collection included ftfty-nlne different species of plants.
Weeds were biaher in nit1'OPn. phosphorus, and calcium than grasses.
and plaDta Il'Owlna on good soU were biaher in nitrogen than stmnar
~ta fI'O~ on poor ~,
~
TABLE IV.
The Average Composition of Common Oklahoma Grasses.
Redtop
6
3
.606
1.M7
.0&0
.208
.111
.s7CS
Av. Comp. in Per cent
Nltr'gn
Phoe. C&lc1wn
Tripled awned grau
Number ot
samples Analyzed
Arlatlda ollgantha
Asroetla
Common Name
1
26
No. SClent1t1c Name
2
Big blue stem
Andropogon acop&rlua
Broom sedge
LJttle blue stem
2
8
"3
.718
.610
.61"
.616
.100
.OM
.072
.oae
.aaa·
.s.
.KG-
.2G
.2'71
alba
S Androposon turcatus
•
Androposon v1rg1nlcua
Silver beard grau
6
C"t
~
.....
Andropocon torreanua
.81.:
e
.128
.,
~
.108
Buffalo IP'888
.087
Grama
.933
Boutebua gracUla
Buchloe dactJ'loldea
Bermuda grau
8
8
Cynodon dactylon
14
0
Da111s grass
6
1.
AVERAOE •...••...80a
1."80
.827
1"1.109
.118
.100
.086
.187
.1'1a
.818
.sa9
.201
.1ee'
••8,
"
Indian
6
gr&I8
Crab grus
gr&I8
10 Paapalum dUatatum
~
Sorghutrum nutana
12 SyDther1.ama aangulna1la
11
=
U
fI.»
~
~-~
~
PROCEEDINGS OF THE OICLAHOI!:s.
Young plants are btgher In mtneral nutrients and nitrogen than older
plants. The stems are lower In nitrogen, phosphorus, and calcium than
the leaves.
Arlstida ollgantba, which is commonly found on very poor soU, conDiodia teres also grows
on land whfeh will not support many other kinds of native plants but was
b1gh in nitrogen. phosphorus, and calcium. '!be feeding power of the
plant 18 the probable explanation ot this difference.
'!be eftect ot weeds on the preservation of plant foods and the possible
stimulation ot nitrogen fixation has meen emphasized.
tained very low amounts ot mineral plant tood.
REPBRENCES
1. Brench1ey. W. E. 1911. The weeds of arable land in relation to the 8011s on
wbich they Il'Ow. Ann. Bot. (London) 26 :166-166.
2. Oampoell. B. G. 1924. Nitrogen content ot weeds. Bot. Gazette 78:103-115.
8. Cooper. H. P. 1930. Ash conatituenta ot pasture grasses, their standard electrode potentia1a and ecological significance. Plant PhysIology 2 :193-214.
-t. Cruickshank, Ethel M. 1026. Report on the seasonal variations in the m.1neral content of pastures. Jour. Agr1. 8c1. 16:89-97.
6. Inee. J. W. 1916. FertlUty and weeds. North Dakota Agri. Exp. 8ta. Bui. 112.
6. KUng. M. 1914 Uber die chemJeche zummenset'.zung einlger Unkrauter 80wie
deren Wert als Putter and Dugemlttel Landw. Vera. Stat. 85 :433-470.
7. Koramo, E. 1930. Unkrauter tm Aokerbau de Neuzeit. Julius 8pringer. Berlin.
8. Mmspaugh, C'. F. 1891. Weeds as fertlUzers. West Va. Agr1. Exp. ata. Bui. 19.
9. Nleuen, N C 1926 Ukrudsvegetatlonen 80m Vejlednlng ved Undersogelser over
MineralJorders Kalktrang Nord. Jordbrugsforak. (Kongres 1. Oslo): 421-433.
10. Pickell, J. M. 1890. Analysis of some Florida weeds and grasses. Fla. Agrl.
Bxp. Stat Bul. 11.
11. Snyder. Harry. 1907. Porage crops of high, medium and low protein content. Minn. Agr!. Exp. Sta. Bul. 101.
12. Stutzer. A. and Seidler. L. 1908. The content of tmportant plant food Ingrec11ente in aome common weeds. Puhl1ng's Landw. Ztg. 57:429-430. 8ee Exp. Bta.
Record 20:760 (1909).
'"8-'"9.
• •••