Response of Curly Mesquite to Height and Frequency of

Response of Curly Mesquite to Height and Frequency of
FEBRUARY 1959
MP-331
. , .. .
Response of Curly Mesquite
to Height and Frequency
of Clipping
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658742
TEXAS
AGRICULTURAL
R.
D.
LEWIS.
DIRECTOR.
EXPERIMENT
COLLEGE
STATION,
STATION
TEXAS
Summary
Since curly mesquite supplies much of the forage produced on the Edwards Plateau,
studies were conducted during 1949-51 at Substation No. 14, Sonora, Texas, relative to
rates of utilization, chemical composition, productivity and longevity of this grass.
Three sites were established in a large pasture on Substation No. 14, Sonora, Texas,
which is located on the Edwards Plateau. These sites were set up o.n different soil phases
where curly mesquite was the predominant grass. Plots 1 by 2 feet in size were established
on each site to determine the effect of clipping frequencies and heights on curly mesquite
in relation to forage productio.n, longevity and soil disturbance. The grass plots were
clipped at intervals of 2 weeks, 4 weeks, twice yearly and once yearly at heights of ground
level, 1 inch, 2 inches and 3 inches for each frequency. Three replicate plots were established for each treatment, making a total of 48 plots o.n each site.
Clipping at the ground level every 2 weeks weakened curly mesquite to the extent
that it almost stopped growth by the end of the second growing season.
Clipping curly mesquite at the ground level every 4 weeks allowed some vegetative
production throughout the second growing season, but the grass was so weakened that
it would have been destroyed by any adverse condition.
Clipping curly mesquite at ground level twice yearly produced the maximum vegetative yields for ail treatments in 1949-50, but the rather heavy reduction in vegetative
yields for 1950 indicated that there eventually might be a loss of producing ability over a
period of years.
Clipping curly mesquite to a height of 1 inch twice yearly produced the second highest forage yields of any of the clipping treatments. These yields might be expected to
be maintained on a sustained basis.
Clipping curly mesquite at a height of 2 inches or above greatly reduced its pot en- .
tial forage-producing ability at all frequencies of clipping.
Clipping curly mesquite at twice-yearly and 4-week frequency -intervals produced higher forage yields than other frequencies of clipping.
The percentages of nitrogen and phosphoric acid in the forage were greater in curly
mesquite forage clipped at the more frequent intervals.
The maximum amounts of nitroge.n and phosphoric acid per plot were obtained at the
4-week clipping interval, with the exception of plots clipped at the ground level. At this
height the maximum amount for the 2 years was obtained from clipping twice yearly.
From the standpoint of forage production, chemical composition and sustained yields
necessary for sound range management, the most desirable method of utilizing curly
mesquite is to clip or graze it to a height of 1 inch, in the shortest possible time, then allow
a rest interval of not less than 4 weeks and not more tha.n 4 months during the growing
season.
Clipping or grazing curly mesquite at the height of 1 inch twice yearly exceeded all
other practices considered in this study. It produced the second highest amount of forage,
increased vegetative litter and decreased soil erosion.
of Curly Mesquite to Height and Frequency of Clipping
L. B. MERRILL and VERNON A. YOUNG*
THE INTRODUCTION OF LIVESTOCK on the
Edward'" Plateau, little or no attention has
'ven to the degree of utilization which
be applied to desirable range plants to obu tained forage yields or to maintain a
ecological balance. As a result, curly mesand other species of the short grasses have
while the more productive bunch
ve decreased. Curly mesquite is the
grass over large areas of the Edwards
It occupies from 50 to 90 percent of the
ground cover and is a major source of liveforage on the Edwards Plateau. Since curly
supplies much of the forage produced
area, there is need for information relato rates of utilization on chemical composiproductivity and longevity of this grass.
to obtain this information were conducSubstation No. 14, Sonora, Texas, in 1949r "nlll1~V':ll' the rainfall was so light and so poorliah·ihnton in 1951 that there was essentially
production obtained from any of the
Growth Characteristics
and Distribution
mesonite was first named Anthephora
by Steudel in 1854. In 1912 Nash
the name to Hilaria belangeri. AccordHitchcook (1950), the type collected in
Texas is Berlandier 1428.
to Hitchcock (1950), curly mesquite
in tufts, sending out slender stolons which
new tufts. The internodes of the stolens
and 5 to 20 centimeters long. The culms
slender, 10 to 30 centimeters tall and
the nodes. The blades are flat, 1 to 2
wide, scabrous, more or less pilose,
short, crowded at the base, often forming
tuft but sometimes long and erect. The
usually 2 to 3 centimeters long with four
clusters of spikelets.
• """'''1'111'''>'
. g to Hoover (1939) , curly mesquite
both by seed and slender stolens. It
tufted, stoloniferous habit which makes
excellent in soil building and erosion
According to the USDA Range Plant
(1937) , curly mesquite is sometimes
thwestern buffal ograss because of its
of growth to the true buffalograss .
, associate in ra nge management, Subs tation
Sonora, Texas; and professor and head, Departof Range and Forestry , Colle g e Station, Texa s .
Curly mesquite produces two seed crops each
year, but depends chiefly on its stolons for reproduction.
Hitchcock (1950) states that curly mesquite
inhabits mesas and plains from Texas to Arizona
and northern Mexico. It is the dominant short
grass of the Texas plains and resists grazing.
The USDA Range Plant Handbook (1937) states,
"Curly mesquite is highly esteemed for forage
wherever it occurs. It is among the first to start
spring growth and responds readily to ~ummer
rains. It is palatable to all classes of lIvestock
for both summer and winter use. The plant
should be protected during its growth period for
Contents
Summary ..... .
Introduction ..... . .... . . .
Growth Characteristics and
Distribution .
. ...... . .
Experimental Area . ..
Location .
Soils . . . . . .. ... .
Climate .... . . ... . . . .. .
Vegetation . . . . . .. ....... .
Methods of Study.
Plot Arran~ement .
Clipping Procedure .
Effects of Heights and Frequencies
of Clipping . . . . . . . . .. . . ..
Heights of Clipping, 1949-50 . .. .
Frequencies of Clipping, 19'49-50.
Heights and Frequencies of
Clipping, 1949 ............ .. . .....
Heights and Frequencies of
Clippi.ng, 1950 .
Heights and Frequencies of
Clipping, 1949-50 ..... .
Effects of Clipping on Chemical
Composition . .
. . . ..... .
Nitrogen Content .
. . . . . ... .
Phosphoric Acid Content ....•. .
Calcium Content . . ...... ..
Crude Fiber
. . ..... . . .... .
Relation of Chemical
Composition and Yield .
Physical Reaction of Soils to Various
Heights and Frequencies
of Clipping.
Literature Cited .
. ... .....
2
3
3
4
4
4
4
4
4
4
5
5
5
5
5
6
6
7
7
8
9
9
9
9
10
best results." Hoover (1939) states, "Curly mesquite grows generally throughout New Mexico,
Texas and Arizona and in scattered stands over
wider areas. It is very resistant to dro ug ht and
very aggressive under heavy grazing."
ation in monthly and yearly precipitations that
occurred during the 3-year period (1949-51) of
the stUdy. The rainfall was so light and so poorly distributed in 1951 that there was essentially
no forage production obtained from any of the
treatments.
Experimental Area
The lowest annual precipitation recorded during the 33 years that records were taken was 6.13
inches in 1951 and the highest was 41.51 inches in
1935. The highest monthly precipitation recorded
for the area was 13.8 inches in September 1932.
LOCATION
Texas Substation No. 14 is located in Southwest Texas in approximately the central portion
of a large area designated as the E dwards Plateau. The station is confined mainly to the northwestern part of E dwards county, but t he northern part, or roughly 640 acres, is in the southern
part of Sutton county. The entire area comprises
3,463 acres. The study area was located approximately in the center of the area.
SOILS
The soils of the Sonora station, according to
Oakes and Crozier (1948), "are representative of
the central and eastern parts of the Edwards Plateau, or approximately 10 million acres. The soils
of the uplands are mainly shallow and stony
(lithosols) and unsuitable for cultivation. Narrow areas of alluvial soils occur along the small
streams in the area. Tarrant stony clay and Tarrant silty clay are the mo.§t extensive soils on the
substation and are closely associated."
The three sites of the study area were located
on the Tarrant silty clay group.
The several
phases of this soil group are similar in physical
and chemical properties. The surface soils in the
Tarrant group, according to Oakes and Crozier
(1948), comprise 5 to 8 inches of grayish brown,
calcareous silty clay, containing fragments of indurated caliche. The surface soil r ests on a bed
of soft or indurated caliche. The phases of the
Tarrant silty soil group support representative
stands of grass of which curly mesquite is the
dominant species.
CLIMATE
The average annual rainfall for the area is
approximately 22 inches, but it varies widely
from year to year. Table 1 shows the wide variTABLE 1. MONTHLY RAINFALL IN INCHES, 1949-51
Month
1949
-
January
February
March
April
May
June
July
August
September
October
November
December
Total
4
- 2.49
3.11
0.31
4.15
5.34
5.47
1.91
4.35
3.52
3.59
0.00
2.48
36.72
1951
1950
-
-
Inches 0.55
0.60
0.00
2.20
2.08
2.35
3.35
1.18
5.53
0.03
0.00
0.00
17.87
-
-
- 0.00
0.20
1.40
0.73
0.46
1.73
0.85
0.27
0.07
0.20
0.04
0.18
6.13
The temperatures recorded for the Sonora station during the past 33 years vary from a maximum of 107 0 F. in July 1944 to a minir(lum of
0° F. in December 1929. The most damaging effect of the high temperatur es on the vegetation
generally occurs in July and August.
VEGETATION
The native vegetation found on Tarrant silty
clay consists mainly of curly mesquite, hairy tridens, red grama, side oats grama, hairy gram a,
threeawn and some silver bluestem, little bluestem, Texas wintergrass and fall witchgrass. A
recent study showed the following average percentage composition of the grasses on the station: curly mesquite, 77 percent; hairy tridens
and red grama, 13 percent; threeawn, 6 percent;
and the more desirable bunch grasses, such as
sideoats grama, hairy grama, silver bluestem, little bluestem and Texas wintergrass, 4 percent.
Methods of Study
PLOT ARRANGEMENT
Three sites were selected on representative
soils on which curly mesquite occurred in practically pure stands. Each site was fenced to exclude livestock.
Forty-eight plots were established on each site. These plots were laid off in
three series of blocks with 16 treatments to a
series. The treatment applied to any given plot
was randomly selected. The manner in which
the plots were laid out on the three sites is illustra ted in Figure 1.
~~~~~D~~b]Du~~~~~
~b]uDD~D~b"J[JDD~~Du
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CLIPPING HEIGHT
O-GROUND LEVEL
I-ONE INCH
2-TWO INCHES
3-THREE INCHES
CLIPPING FREQUENCY
2W-TWO WEEK INTERVAL
4W-FOUR WEEK INTERVAL
2Y-TWI CE YEARLY
IY-ONCE YEARLY
Figure 1. Diagram of a typical plot arrangement within
sites illustrating randomization of height and frequency of
clipping of curly mesquite grass. All plots are 1 foot wide
and 2 feet long. The interval between plots is 6 inches.
FREQUENCIES OF CLIPPING, 1949-50
clipping treatments were made to dethe reaction of curly mesquite to various
and frequencies of grazing. Clippings
at four heights: ground level, 1 inch,
and 3 inches above the ground. For each
clippings were made at four frequency
: ~ weeks, 4 weeks, .twice yearly and
yearly. The twice-yearly clippings were
when the curly mesquite plants were in full
while the once-yearly clippings were made
ber when all plants were dormant.
vegetation on a given plot was clipped at
height and fequency; however, only
mesquite foliage from each plot w-as colpaper bags. These clippings were air
3 weeks and weighed separately to the
half gram. After the weights of the
clippings were determined for the vargs treatments, the total annual forage
was composited for each of the 16
on each of the three sites, making a
of 48 composited forage samples. Each of
composite samples was sent to the Texas
Experiment Station chemistry labwhere the percentages of nitrogen, phoscalcium and crude fiber were determined.
esl~rna1ted
5
of Heights and Frequencies
of Clipping
forage yields obtained from curly mesthis study were found to correlate closeboth height and frequency of clipping or
OF CLIPPING, 1949-50
2 shows that for 1949, the forage yields
mesquite in pounds per acre for the varhts of clipping were 3,080 at ground
. 2,713 at 1 inch; 1,864 at 2 inches and 851
inches when all frequencies of clipping were
. The highest yields for 1949 were obby clipping at ground level and the lowest
were obtained by clipping 3 inches above
ground.
forage yields were lower in 1950 as a reless rainfall, Table 2. The plots clipped at
nd level declined sharply in forage proas compared with those of the other three
heights. Average forage yields for var. heights in pounds per acre for 1950
1,322 at ground level; 1,711 at 1 inch; 1,356
inches and 939 at 3 inches. The sharp rein forage yields from clipping at the
level reveals damage to the plants under
treatments. The plots clipped at the 3-inch
did not decline in forage production the sec, notwithstanding the lower rainfall con; however, the forage yields for the 3-inch
of clipping were lower than those obtained
the other three heights.
Table 2 shows that in 1949 the average yields
in pounds per acre were 1,669 at 2 weeks, 2,174
at 4 weeks, 2,596 at twice-yearly and 2,339 at
once-yearly clipping intervals. The highest yields
were thus obtained from clipping twice yearly
and the lowest yields from clipping every 2 weeks.
All forage yields were lower in 1950 than in
1949 but the 1950 yields were similar to 1949 in
relative amounts obtained from different frequencies of clipping. The twice-yearly frequency
gave highest yields and the two-week intervals
the lowest. The 1950 forage yields for the different clipping frequencies, when all heights were
averaged, were 992, 1,198, 1,845 and 1,293 pounds
per acre, respectively, for the 2-week, 4-week,
twice-yearly and once-yearly frequencies.
HEIGHTS AND FREQUENCIES
OF CLIPPING. 1949
Figure 2 shows the average forage yields of
curly mesquite in pounds per acre for different
heights and frequencies of clipping. Forage yields
from plots on three sites are averaged.
There is a considerable variation from these
average values on the three different sites. However, the values in Figure 2 are fairly representative of all sites. The forage production from
the various clipping heights was highest at the
ground level, second highest at 1 inch, third highest at 2 inches and lowest at 3 inches. The forage production from the various clipping frequencies on these sites was highest at the twice-yearly
interval, second highest at the once-yearly interval, third highest at the 4-week interval and lowest at the 2-week interval.
When curly mesquite was clipped at the
ground level an<i at I-inch heights, average forage production increased greatly as the frequency
of clipping decreased from a 2-week to a twiceyearly clipping interval. Yearly clipping at these
heights gave noticeably less production than the
twice-yearly clipping. At the 2-inch and 3-inch
clipping heights, little variation occurred in fora.g e yields due to different frequencies of clipping. There was, however, a slightly higher forage yield for the 4-week clipning interval than
for any other frequency for these two clipping
TABLE 2.
1949-501
CLIPPING HEIGHTS FROM CURLY MESQUITE,
Height of clipping
Year
Frequency of clipping
Ground One Two Three Two Four Twice Once
level inch inches inches weeks weeks yearly yearly
1949
1950
- - - - - Pounds per acre - - - - - All frequencies combined
All heights combined
3080 2713 1864
854
1669 2174 2596 2339
1322 1711 1356
939
992 1198 1845 1293
The
lEach weight represents an average of 36 plots.
weights for heights of clipping include four frequencies of
clipping with nine plots for each frequency, while the
weights for frequency of clipping include four heights with
nine plots for each height.
5
·CLlPPED AT GROUND LEVEL
3840
/, ,
~3360
u
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cr
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Q.
II)
~2880
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V/
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"CLIPPED AT ONE INCH
I
z
o
;:: 2400
g
o
o
cr
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1920
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.... ..... ..
'
.. ' ....
CLIPPED AT TWO INCHES
'.
...... ....
>
IAJ
~
ffi 1440
~
960
-' ........
...-- .............
"""'-. "'"
.2~E~~ ~~ INCHES
480
TWO WEEKS
FOUR WEEKS
TWICE YEARLY
FREQUENCY OF CLIPPING
ONCE YEARLY
Figure 2. Forage production of curly mesquite clipped
at four heights and four frequencies on three sites (1949).
Each point on the graph represents the average weight of
forage for nine plots.
heights. Forage yields decreased slightly when
the plots were clipped twice yearly and once yearly at the 3-inch clipping height.
3360
",2880
a:
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~
;2400
~
I
z
21920
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CLIPPED AT ONE INCH/ /
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If
~1440
:-:-::-:-:::-:~:-:"""'"''''''''''''''
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!960
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• --.
' ••
..........
~
~I~~. AT TWO INCHES
..........
........
CLIPPED AT THREE INCHES
480
o
~-r------~--------r-------4---
TWO WEEKS
FOUR WEEKS
TWICE YEARLY
FREQUENCY OF CLIPPING
ONCE YEARLY
Figure 3. Forage production of curly mesquite clipped
at four heights and four frequencies on three sites (1950).
Each point on the graph represents the average weight of
forage for nine plots.
6
Canfield (1939) reported that clipping at 2
inches or less inj ured black grama at all frequencies, while tobosagrass was Injured only when
clipped at 1 or 2-week intervalS. l 'obosagrass was
stImulated by frequent clipping at a heIght of 4
inches. Lang and Barnes (1942) found during a
2-year period that clipping at ground levels at 3week intervals produced more forage than harvesting at the end of the growing season only.
HEIGHTS AND FREQUENCIES
OF CLIPPING, 1950
The average forage yields of curly mesquite
in pounds per acre for the various heights and
frequencies of clipping, with the forage yields
from plots of all three sites averaged tog .her,
are shown in Figure 3. When all frequencies were
averaged, the forage production from the various
clipping sites was highest at 1 inch, second highest at 2 inches, third highest at the ground level
and lowest at three inches. The forage production from the various clipping frequencies on
these sites was highest at the twice-yearly interval, second highest at the once-yearly interval,
third highest at the 4-week interval and lowest
at the 2-week interval.
When curly mesquite was clipped at the ground
level and at I-inch heights, the average forage
production from these treatments on plots on all
sites showed a marked increase as the frequency
of clipping was decreased from a 2-week period
to a twice-yearly period. There was then a sharp
decline in the forage production of curly mesquite
when the clipping frequency was decreased from
a twice-yearly period to a once-yearly period.
The lowest and second lowest forage production for all sites for 1950 was obtained by clipping at the ground level at 2-week and 4-week intervals, when forage production was 86 and 519
pounds per acre, respectively. The greatest forage production in 1950 was 2,555 pounds per acre,
which was obtained by clipping curly mesquite at
the ground level at twice-yearly intervals. The
second greatest forage production of 2,271 pounds
per acre was obtained by clipping at I -inch at
twice-yearly intervals.
Only small differences
were obtained in forage production between frequencies of clipping when heights of clipping
were at 2 and 3 inches. Clipping at the 2-inch
height produced the highest yield at the twiceyearly interval and the lowest at the once-yearly
interval. At the 3-inch clipping height, a slight
but constant decline in forage production was obtained when the clipping frequency was decreased from a 2-week interval to a once-yearly interval.
HEIGHTS AND FREQUENCIES
OF CLIPPING, 1949-50
Figure 4 shows graphically the average forage yields of curly mesquite in pounds per acre
for the various heights and freauencies of clipping. The forage yields from plots of all three
siteR were averaged together for 1949-50.
When curly mesquite was clipped at the
ground level, clipping at the 2-week interval resulted in the greatest reduction in forage yield
1949 to 1950. Clipping at the 4-week interproduced the second lowest forage yields and
howed the second greatest reduction in foryields from 1949 to 1950.
eaver and Hansen (1941) fonnd that during
first year frequent clippings of prairie dropand Junegrass yielded more forage than the
ly clipping but during the second year
clippings greatly decreased the plant
forage production. N ewell and Kiem
found clipping short grasses three to five
ly increased forage yields over a 3-year
while clipping once yearly resulted in a
stand.
the ground level, clipping at the twiceinterval in 1949 produced the greatest forof any of the clipping frequencies. Clipat the once-yearly interval in 1949 produced
highest forage yield. The overall rein yield from 1949 to 1950 may be partiaccounted for by the decreased rainfall of
second year.
lowest forage yields for the I-inch clipheight were obtained from the 2-week inter1949-50. The second lowest forage yields
I-inch clipping height were obtained at
interval in 1949 but at the once-yearly
in 1950. The highest forage yields were
at the twice-yearly frequency interval
0, while the next highest yields were
at the once-yearly interval in 1949
the 4-week interval in 1950. At the I-inch
height, there was no marked reduction
forage yields between 1949 and 1950 for
the clipping frequencies. There was, howconsistent reduction in yield for 1950, but
y was caused by the lower rainfall in
Table 1.
the 2-inch clipping height, there was little
in forage production due to frequencies
for 1949-50. In 1949 at this height.
forage yield was obtained at the 4,,1'Tllnn110' interval, while the lowest yield was
the twice-yearly clipping interval.
forage yield in 1950 was obtained at
tWlC~P.-V'P'al y clipping interval, and the lowest
obtained at the once-yearly clipping inThere was much less variation between
for the 2 years at the 2-inch clipping
than at either the 1 inch or the ground
heights.
curly mesquite was clipped at 3 inches,
was slight difference in forage yield 0ue to
of clipping. The 3-inch height of clipnced less variation in forage yields be1949 and 1950 than any of the other three
heights.
5
of
Clipping on Chemical
Composition
3 shows that the nitrogen and phosacid contents of curly mesquite forage
FREQUENCY OF CLIPPING
TWO WEEKS
1949- 50
HEIGHT OF CLIPPING
FOUR WEEKS
1949-50
TWICE YEARLY
1949-50
ONCE YEARLY
1949-50
3840
3360
c(
GROUND LEVEL
~
2880
2400
1920
1440
"-
960
480
3840
I INCH
~
3360
"-
2400
~
1920
2880
1440
960
480
2880
c(
2 INCHES
.r
2400
1920
1440
If
960
480
~
c(
3 INCHES
.r
~
~
2880
2400
1920
1440
960
480
Figure 4. Average yearly forage production of curly
mesquite clipped at various heights and frequencies during
1949-50. Each bar on the graph represents the average
forage yield for nine plots.
were greatly affected by both height and frequency of clipping.
NITROGEN CONTENT
The nitrogen COIl-tent of the forage as affected
by treatment varied somewhat between clipping
sites, but since there were no great variations,
the values for all sites have been averaged in
Table 4. The nitrogen content of curly mesquite
forage was found to be highest at the 2-week
clipping interval and lowest at the once-yearly interval. The nitrogen content of the forage decreased in direct proportion as the clipping frequency decreased from a 2-week to a once-yearly
interval. This was primarily because the more
frequent clippings were from green forage. Similar results were reported by Fraps and Cory
(1940) who reported 15.04 percent protein from
fresh green forage and 5.15 percent from cured
forage. Stanley and Hodgson (1938) also showed
that moisture, crude protein and phosphorus
were much higher in green than in mature forage.
The effect of the height and frequency of
clipping were found to be closely related with
respect to the nitrogen content of the forage. At
the 2-week clipping interval, the nitrogen content
of the forage was highest at the I-inch and
ground-level clipping heights and lowest at the
3-inch height. At the 4-week clipping frequency
the nitrogen content was highest when the grass
7
TABLE 3. CHEMICAL COMPOSITIO~ OF CURLY MESQUITE AS AFFECTED BY VARIOUS HEIGHTS AND FREQUENCIES
OF CLIPPING ON THREE SITES, 19491
Clipped at ground
Site
Clipped at 1 inch
Twi.
yrly.
Clipped at 2 inches
Two
wks.
Four
wks.
Twi.
yrly.
Once
yrly.
Two
wks.
Four
wks.
Once
yrly.
I
2
3
Average
.98
1.67
1.90
1.52
.98
2.08
1.85
1.84
.87
.80
1.14
.94
.65
.92
1.03
.87
.63
.72
.90
.75
.72
.78
.94
.81
Calcium, percent
.60
.66
.66
.66
.64
.73
.71
.73
.74
.71
.66
.68
.70
.72
.79
.74
.71
.70
.78
.73
1
2
3
Average
1.67
1.91
2.00
1.86
1.60
1.72
1.83
1.72
.90
.86
1.14
.97
.74
.72
1.05
.84
1.78
1.80
2.02
1.87
1.58
1.59
1.88
1.68
Nitrogen, percent
.86
.75
1.53
.85
.72
1.56
1.16
.92
1.89
.96
.80
1.66
1.35
1.25
1.63
1.41
1
2
3
Average
.50
.38
.41
.43
.50
.34
.35
.40
.33
.16
.20
.23
.25
.15
.19
.20
.52
.32
.39
.41
1
2
3
Average
23.70
23.57
24.10
23.79
24.25
23.55
24.48
24.09
25.44
25.01
26.10
25.52
25.31
25.47
26.01
25.60
25.63
25.07
24.93
25.21
Phosphoric
.44
.24
.15
.30
.37
.19
.37
.19
25.44
25.97
25.66
25.69
Crude
25.58
25.20
26.07
25.62
Two
wks.
acid, percent
.23
.44
.14
.32
.17
.32
.18
.36
fiber, percent
25.15
27.81
25.51
26.26
26.48
25.30
25.71
26.46
Four
wks.
Twi. Once
yrly. yrly.
Clipped at 3 inches
Two
wks.
Four
wks.
Twi.
yrly.
Once
yrly.
.72
.66
.64
.67
.71
.56
.76
.68
.56
.67
.85
.69
.71
.81
.80
.77
.77
.59
.49
.62
.91
.84
1.19
.98
.71
.72
.98
.80
1.28
1.32
1.76
1.45
1.41
1.28
1.57
1.42
.84
.76
1.11
.90
.67
.70
1.09
.39
.25
.26
.30
.29
.16
.20
.22
.19
.14
.18
.17
.38
.25
.33
.32
.35
.25
.29
.30
.35
.14
.19
.20
.21
.12
.18
.17
25.33
26.46
25.59
25.79
24.56
24.11
22.91
23.86
24.62
25.74
26.99
25.45
26.78
25.25
25.29
25.44
26.61
26.11
26.42
26.38
25.07
27.17
26.07
26.10
25.46
25.82
26.11
25.46
.a2
1The chemical analysis was made by the Office of the State Chemist of the Texas Agricultural Experiment Station.
week clipping interval and lowest at the onceyearly interval. There was a constant decline in
the phosphoric acid content of forage obtained
as the length of time between clipping increased
from a 2-week interval to a once-yearly interval.
was clipped at the ground level and decreased
steadily as the height of clipping increased. However, the nitrogen content of the forage was almost identical from clipping heights of 2 and 3
inches. At the twice yearly and once-yearly
clipping intervals, the nitrogen content of the
forage was affected little by the height of clipping.
The effect of the height of clipping on the
prosphoric acid content of the curly mesquite forage was found to be closely related to the frequency of clipping. At both the 2-week and 4week clipping intervals, the phosphoric acid content of the forage was highest at the ground
level of clipping and lowest at the 3-inch level.
There was a steady decrease in the phosphoric
acid content of the grass as the height of clipping increased from the ground level to a 3-inch
PHOSPHORIC ACID CONTENT
The phosphoric acid content of the curly mesquite forage, like the nitrogen content, varied
rather sharply between different heights and
frequencies of clipping. When an average for
three clipping sites was taken, the phosphoric
acid content was found to be highest at the 2TABLE 4.
TOTAL PRODUCTION OF FORAGE, NITROGEN AND PHO!?PHORIC ACID IN POUNDS PER ACRE, 1949-501
Clipped at 1 inch
Clipped at ground
1949
Forage
Yield
Nitrogen
Yield
Clipped at 2 inches
Clipped at 3 inches
Two
wks.
Four Twice Once
wks. yrly. yrly.
Two
wks.
Four Twice Once
wks. yrly. yrly.
Two
wks.
Four Twice Once
wks. yrly. yrly.
Two
wks.
Four Twice Once
wks. yrly. yrly.
1791
2723
4240
3563
1945
2656
3390
2852
1810
2050
1705
1892
1128
1269
1047
1037
33
47
41
30
36
45
33
23
30
29
17
15
16
18
9
8
2.1
1.8
P~ 0 5
Yield
1950
Forage
Yield
Nitrogen
Yield
P20 5
Yield
7.7
86
0.4
10.9
9.7
7.1
8.0
9.8
6.4
5.1
6.5
6.1
3.7
3.2
3.6
3.8
591
2555
2060
1393
1604
2271
1570
1364
1565
1585
908
1124
1028
970
634
10
25
17
26
27
22
13
23
22
16
7
16
15
9
5
1.9
1.1
2.4
5.9
4.1
5.7
6.0
4.3
2.8
4.9
4.7
3.5
1.5
3.6
3.1
1Chemical analyses of the clippings were made for 1949 only. These percentage composition values were applied to forage
yields to obtain the amount of nitrogen and P 2 0 5 produced per plot for both years. The production of nitrogen and P20 5
for 1950 are therefore speculative and are used primarily for comparative purposes.
8
Figure S. An average curly
mesquite plot I by 2 feet in size,
clipped at the ground level every
2 weeks.
height. There was little difference in phosphoric
acid content of curly mesquite forage due to
height of clipping at either the twice-yearly or
the once-yearly clipping frequency. There was,
however, a slight increase in phosphoric acid content when the grass was clipped at the ground
level.
CALCIUM CONTENT
The data given in Table 3 show that there is
a tendency for the calcium content of curly mesquite forage to increase as the length of time between clipping is increased from a 2-week to a
twice-yearly interval. However, from the twice
yearly interval to the once-year:ly clipping interval there was a marked decrease in the calcium
content of the curly mesquite forage. Therefore,
the highest calcium contents generally were obtained when the grass was clipped twice yearly.
The twice-yearly clippings were made as curly
mesquite reached maturity, while the once-yearly
clippings were made at a stage beyond maturity.
This probably accounts for the decline in the calcium content of the forage.
Table 3 also shows a high calcium content of
forage from curly mesquite which was clipped at
the ground level. The calcium contents of the
clippings were especially high in forage which
was clipped at the ground level at 2-week and 4week intervals. The higher calcium content for
these treatments may be attributed to small pebbles of calcium carbonate which littered the
ground on all sites. These may have been picked
up when clipping curly mesquite so near the
ground and thus analyzed with the sample.
at 2 and 3-inch heights, both nitrogen and phosphoric acid production decreased when the frequency of clipping decreased from a 2-week interval to a once-yearly interval. Forage production, however, was generally greatest at the 4week or twice-yearly clipping intervals. When
curly mesquite was clipped at the ground level,
the largest nitrogen and phosphoric acid production was obtained by clipping at a 4-week interval
in 1949, but at twice-yearly intervals in 1950.
Maximum forage production at this level was
obtained by clipping at twice-yearly intervals and
once-yearly intervals. Clippings at I-inch heights
produced the maximum of nitrogen and phosphoric acid at 4-week clipping intervals. Forage
production, however, was greatest at the twiceyearly clipping intervals.
Physical Reaction of Soils to Various
Heights and Frequencies of Clipping
Soil erosion is often very severe on pastures
where curly mesquite is kept short. The various
treatments in this study, corresponding to several intensities of grazing, offered an opportunity to study erosion.
Figue 5 shows an average plot which was clipped at the ground level every 2 weeks. The ends
of the steel rod extending across the plot were
resting on the original ground level. Practically
all curly mesquite plants were killed, leaving the
CRUDE FIBER
Table 3 shows that there is little variation in
the crude fiber content of curly mesquite due to
variation in height and frequency of clipping.
Clippillg at the ground level at both the 2-week
and the 4-week intervals resulted in lower crude
fiber content in the forage. This would be expected, however. since the frequent clippings
maintained the forage in a green stage for the
greater part of the time.
.
RELATION OF CHEMICAL
COMPOSITION AND YIELD
Total forage production is not always a reliable criterion of the best system of management, Table 4. When curly mesquite was clipped
Figure 6. An average curly mesquite plot I by 2 feet
in size, clipped at the ground level every 4 weeks.
9
dent when frequency of clipping was at intervals
of 4 weeks or greater. Some soil erosion was evident for all frequencies when curly mesquite was
clipped at the ground, however, the erosion was
pronounced only for the clipping intervals of 2
weeks and 4 weeks.
Literature Cited
Canfield, R. H. 1939. The effect of intensity and
frequency of clipping on density and yield of
black gram a and tobosa grass. U. S. Dept.
Agr. Tech. Bu!. 681.
Figure 7. An average curly mesquite plot I by 2 feet
in size. clipped at the ground level once yearly.
soil almost entirely exposed. The rule in the
center of the plot was calibrated in inches and
showed that approximately an inch of soil was
lost due to wind and water erosion.
Figure 6 shows an average plot which was
clipped at the ground level at intervals of 4 weeks.
After 2 years the ground was practically bare and
the curly mesquite was in a weakened condition.
However, less than one-fourth inch of soil had
eroded.
Figure 7 shows an average plot which was
clipped at the ground level once yearly. The clipping was made in December. The curly mesquite,
which had just been clipped when the picture was
taken, was dormant but apparently in good condition. Little bare ground or erosion was evident.
Figure 8 shows an average plot which was
clipped at a height of 1 inch every 2 weeks. The
curly mesquite plants were somewhat pedestaled,
which would indicate that some erosion had taken
place, however, the steel rod, the ends of which
are resting on the original ground level, showed
that little soil loss had occured on the plot.
Figures 5 through 8 show the severe clipping
treatments. When curly mesquite was clipped at
heights above 1 inch, little or no soil erosion occurred regardless of the frequency of clipping. At
the height of 1 inch little or no erosion was evi-
Fraps, G. S. and V. L. Cory. 1940. Composition
and utilization of range forage of SuttOfl and
Edwarcis Counties. Texas Agr. Expt. Sta. Bu!.
586.
Hitchcock, A. S. 1950. Manual of the grasses of
the United States. 2nd edition. Rev. by Agnes
Chase. U. S. Dept. Agr. Misc. Pub. 200.
Hoover, M. M. 1939. Native and adapted grasses
for conservation of soil and moisture in the
Great Plains and Western States. U. S. Dept.
Agr. Farmers Bu!. 1812.
Lang, Robert and O. K. Barnes. 1942. Range forage analysis in relation to time and frequency
of harvest. Wyo. Agr. Expt. Sta. Bu!. 153.
Newell, L. C. and F. D. Keirn. 1947. Effects of
mowing frequency on the yield and protein
content of several grasses grown in pure
stands. Nebr. Agr. Expt. Sta. Res. Bu!. 150.
Oakes, Harvey and B. B. Crozier. 1949. A detailed
soil survey of Texas Agricultural Experiment
Station Substation No. 14, Sonora, Texas. Unpublished Report.
Stanley, E. B. and C. W. Hodgson. 1938. Seasonal
changes in chemical composition of some Arizona range grasses.
Ariz. Agr. Expt. Sta.
Tech. Bu!. 73.
U. S. Forest Service. 1948. Range plant handbook. U. S. Dept. Agr.
Weaver, J. E. and W. W. Hansen. 1941. Native
midwestern pastures. Nebr. Conservation Bu!.
22.
Figure 8. An average curly
mesquite plot I by 2 feet in size.
clipped at a height of 1 inch
every 2 weeks.
10
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