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Circular No. 870

|: Efficient Use of Annual Plants

on Cattle Ranges in the
California Foothills _:
2 i Kh aise Peasee Gamsetaticnde
4 | and
M. Ww. PALBOYY Associate Director;

California Forest and Range Experiment ana

_ Forest Service

"UNITED STATES fat ice wep T OF AGRI CULTURE

“ ! (WASHINGTON, FDL Col ahem

CONTENTS

Introduction
Experimental area and methods- - -- -
hang ranch operations to forage

y/
Supplementing range forage dur-
ing critical periods. ___.__----
Lengthening the period of ade-
@ueitentorage tes 7 oer
Adjusting ranch stocking to herbage
KLOGUCIOnes ne eer is Ae
Effect of site on grazing capacity
Effect of annual precipitation on
herbacevieldwe lee. So Loe

Page

16

Page
Stocking to meet forage fluctua-
CLOTS GR i en ate 28
Selecting the most efficient degree of
grazin
Effects of different degrees of
grazing on cattle production__ 32
Effects of different degrees of
grazing on herbage production 34
Recognizing satisfactory range

Utihzatione~ 5 © Soe Sm 42
SUMMA ATY Leek eee mci ABN del LU Ba 45
Common and botanical names of

species mentioned______________- 50
MiteraturexciGeds waves «aur eens il

PPP BEEP LPEPLEP PDP LE LPL LE LPR LESLIE

For sale by the Superintendent of Documents, U. S. Government Printing Office
Washington 25, D. C. — Price 20 cents

(

\

Circular No. 870)

May 1951 ¢ Washington, D. C.

UNTFED SFATES DEPARTMENT. OF AGRICULTURE.

Efficient Use of Annual Plants on Cattle

Ranges in the California Foothills
2

By, J. R. BENTLEY, range conservationist, and M. W. TaBor, associate director,!

California Forest and Range Experiment Station 2

INTRODUCTION

The California foothills (fig. 1) comprise the most important range
area within the State. These lands border the great Central Valley
and enclose numerous smaller valleys within the Coast Ranges. Primary
use of foothill range lands is production of livestock. This use is closely
associated with the highly intensified valley agriculture, which supplies
hay, grain, and agricultural byproducts to supplement range forage
and furnishes seasonal pasturage for livestock carried part of the year on
foothill range. Also, some of the livestock are grazed during the summer
in the mountainous lands above the foothills. But by far the greatest
part of the State’s range grazing capacity is in the foothills.

The foothill area has relatively mild, wet winters and hot, dry summers.
Thus, some green forage is available during the fall and winter, plant
growth i is at its height during the spring, but the plants are dry ‘during
the summer and early fall.

Annual plants dominate the herbaceous cover and occur with varying
amounts of bunchgrasses and other perennial species. ‘This cover is
found over the grass and woodland-grass vegetative types, as well as
the more open phases of the chaparral.

1 Credit is due to two former forest ecologists of the California Forest and Range
Experiment Station: F. G. Renner, who was in charge of planning, establishing,
and supervising the forage experiments in 1934-35, and H. H. Biswell, in charge of
the experiments 1936-40. Assistance in sampling of forage and in compilation and
analysis of data was obtained from members of the staff of the California Forest and
Range Experiment Station and from many temporary field assistants and members
of emergency agencies, particularly Civilian Conservation Corps and Civilian Public
Service.

2 Maintained by the Forest Service, U. S. Department of Agriculture, in coopera-
tion with the University of California ‘at Berkeley, Calif.

2 CIRCULAR 870, U. 8S. DEPARTMENT OF AGRICULTURE

jy FOOTHILL RANGE

@ SAN JOAQUIN EXPERIMENTAL RANGE

FiGuRE 1.—Approximate location of foothill range in California.

The foothill range area includes the sloping plains and rolling hills
bordering the valleys and extends upward through hills of rolling-to-
steep topography; elevation varies from near sea level to about 4,000
feet; the soils are exceedingly diverse; and total annual precipitation
ranges from less than 10 inches in the plains at the south end of the San
Joaquin Valley to more than 40 inches in the upper foothills at the north
end of the Sacramento Valley.

Local demand for livestock products has increased as a result of
rapid growth of population, and the California livestock industry is
increasingly aware of the need for both the fullest sustained production
of forage and the greatest efficiency in its use. The goal is to obtain
high livestock production while maintaining or improving the forage
cover. The long-time objective of management is to obtain the most
productive mixture of the best forage plants, including both perennials
and annuals. But over millions of acres the immediate problem of live-

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 3

stock operators is how to obtain the most efficient use of the present
cover of annual plants.

This circular reports studies of use of foothill range by cattle at the
San Joaquin Experimental Range.? The studies have shown how range
management can be geared to the typical yearly pattern of annual-
plant growth, with sufficient flexibility in ranch operation from year
to year to meet variations in time of growth and most of the fluctuations
in forage yield. The studies have also shown the grazing capacity of
different kinds of foothill range, and how plant growth and cattle produc-
tion are affected by different degrees of grazing. Finally, the studies
have developed practical guides for increasing the efficiency of range use.

EXPERIMENTAL AREA AND METHODS

The San Joaquin Experimental Range, a tract of approximately 4,500
acres, is located within the woodland-grass vegetation type in the Sierra
Nevada foothills on the east side of the San Joaquin Valley. Elevation
of the experimental area is from about 700 to 1,700 feet above sea level.
The soils on the slopes, mainly sandy loams, average abcut 11% feet in
depth and have numerous outcroppings of the granitic bedrock. The
bottom-land soils, transported from the slopes above, are of heavier
texture and are deeper and more productive.

The herbaceous cover on the experimental range contains a fairly
representative mixture of annuals; it includes grasses, grasslike plants,
filaree,t clovers, other legumes, and numerous miscellaneous species.
Soft chess, broadleaf filarees, and foxtail fescue, which occur on most
foothill ranges, produce about two-thirds of the herbage. Perennials,
mainly rushes in the bottom lands, compose about 3 percent of the
herbage yields. The native pine bluegrass, a small early-drying perennial,
is common but produces less than 1 percent of the herbage. The more
valuable native perennial bunchgrasses, stipas or needlegrasses, are
virtually absent on the experimental area.

On some heavier and more productive soils of the foothill area, bur-
clover, alfileria or redstem filaree, and wild oat, highly palatable annuals,
are much more abundant than on the experimental range, and the forage
is generally considered ‘‘stronger;’’? but the problems of management are
similar to those on the experimental range. Problems not experienced
in the studies do occur, however, on more arid foothill ranges where
average annual precipitation is approximately 5 to 12 inches and forage
production fluctuates more widely from year to year.

The guides that were developed from the studies apply in management
of the annual-plant portion of the vegetative cover on most foothill
ranges. Specific effects of weather and grazing management on growth
of individual plant species, however, may apply only in the “Granite

3 These studies were part of the cooperative interagency research program at the
San Joaquin Experimental Range, O’Neals, Calif., during the period 1935-48. In
this program the University of California was responsible for the cattle studies, and
the California Forest and Range Experiment Station for the studies of range forage
production and utilization. Additional information on al! phases of this interagency
program is given in The San Joaquin Experimental Range (7) (see Literature cited,

HO),

: 4 Common and botanical names of the species mentioned in this circular are listed
on p. 50.

Pasture numbers
Horse pasture
Natural area

_ Corral

1/2 | Miles

Figure 2.—Experimental pasture layout at the San Joaquin Experimental Range.

Area”’ (most of the foothills on the east side of the San Joaquin Valley,
from Madera County southward).

For study purposes the range is subdivided into a number of pastures
(fig. 2). Most of the forage studies were made in experimental pastures
1 to 6, which were devoted primarily to determining the effect of different
intensities of grazing on both cattle and range. When not in these
grazing-intensity pastures, the cattle were held in pastures /0, 12, and 14.
The remainder of the experimental pastures (7, 8, 9, 11, and 13) were
used for trials on cattle feeding and for grazing of miscellaneous animals.

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 5

Studies of range fertilization, range reseeding, range rodents, and other
subjects were made in portions of several pastures. The effects on
vegetation of complete exclusion of livestock grazing were studied in an
ungrazed ‘‘natural area.”’

Ninety head of breeding cows were used in the grazing-intensity
studies. From approximately August 1 to February 1 they were divided
into two equal herds. One, the supplemented ‘A’ herd, receiving con-
centrate feeds in addition to natural forage, was grazed in pastures 10
and 12. The second, the unsupplemented ‘B” herd, was grazed in
pasture 74 with access only to the natural forage. During the remainder
of the year, from approximately February 1 to August 1, none of the
cows received supplements; 15 cows with their calves were placed in each
of the grazing-intensity pastures / to 6. Pastures /, 2, and 4 each held 8
cows from the “‘A”’ herd and 7 from the “‘B” herd; pastures 3, 5, and 6
each held 7 cows from the ‘‘A”’ herd and 8 from the “B”’ herd. A bull
was with each group of cows from January 1 until May 1.

Approximate rates of stocking in the six grazing-intensity pastures
were: 10 acres per cow in pastures / (154 acres) and 3 (155 acres),
15 acres per cow in pastures 2 (230 acres) and 5 (250 acres), and 20
acres per cow in pastures 4 (309 acres) and 6 (316 acres). The cows
were placed in all six pastures in late winter at the time when new green
forage over most of the range was judged adequate to maintain a cow
with a calf for the remainder of the winter. They remained in these six
pastures until after the herbage was mature and dry and were removed
when the heaviest-used pasture was judged closely grazed.

Measurements were made each spring to determine (1) the plants
that make up the forage, and (2) how herbage production varies with
grazing intensity and year-to-year differences in weather. The percent
of the ground covered by herbaceous vegetation, plant density, and the
percent of the cover made up by each plant species in each of the six
erazing-intensity units were estimated on square-foot quadrats: 300
quadrats per experimental pasture in 1936; and 80 to 160 quadrats per
pasture in 1938, 1939, 1940, and 1948. Continuity of density records
was maintained in 1941, 1942, and 1944 by estimates from 100 quadrats
in lightly grazed pasture 2, and closely grazed pasture 3. Density
measurements were made as nearly as possible at the time of maximum
plant density in April, when the early-maturing species first started to
dry. ;

The yield of herbage on slopes was measured in May 1942 on 100
square-foot quadrats in each of pastures 2 and 3. The vegetation on
each quadrat was protected from grazing by small wire ‘‘cages’’ (fig. 3)
and was clipped at 14-inch stubble height in May, after almost all the
herbage had made full growth and started to dry. Herbage from each
quadrat was placed in a paper bag, dried in a greenhouse, and weighed
when relative humidity of air was below approximately 30 percent. In
1943, 1944, and 1945 the yield on slopes was measured on 100 quadrats
in each of pastures /, 2, and 3 and on swales, or bottom land, on 60 to 100
quadrats in each pasture. The vegetation was protected from grazing,
clipped, sorted, and weighed as in 1942. The wire cages were moved to
new locations each January.

The total yield of herbage within a 14-acre area from which cattle and
rodents were excluded was measured on 100 quadrats at plant maturity
each spring during an 8-year period, 1940-47. In addition, the dry

6 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

F—460560

FicurE 3.—Cage made of 2-inch mesh poultry netting used to protect vegetation
from grazing by cattle.

herbage was measured on another set of quadrats each fall during a 7-year
period, 1936-42. This 14-acre area was located within pasture /.

To facilitate comparison of yields between experimental range units
with different amounts of waste area, yields were measured only on
productive, grazable land. Rocks, brush, and other waste areas were
excluded from the samples. Then the amount of waste area was measured
in 1942 on 16 transects across each of the six grazing-intensity pastures
and subtracted from the total area to determine the grazable acreage.
In evaluating the productivity and grazing capacity of different kinds of
land, a range site classification was employed. The development of this
classification entailed the making, in 1945, of a site-class map of the six
grazing-intensity pastures.

Measurements were also made to determine the seasonal pattern of
plant growth. During the 1937-45 period, plant density and height
were measured at one fixed station in each of the six pastures at intervals
of 1 to 4 weeks. The average growth and development of vegetation
by sites were determined in each year by observations of plant growth
over all of the experimental pastures and by color photographs at selected
stations. Detailed observations were made on critical features of plant
growth, such as the amount of precipitation required to germinate the
seed and start growth of the several species, growth on south slopes
contrasted with growth on north slopes, growth at different air tempera-
tures, and the relative dates of flowering, fruiting, and drying of the
different species on different sites. Many comparisons of plant heights
were made across fence lines between experimental pastures grazed at
different degrees and between spots grazed to different degrees within
pastures.

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS

a

TaBLE 1.—Monthly precipitation at San Joaquin Experimental Range,
September 1934-August 1948

Year Sept. Oct. Nov. Dee. Jan. Feb. Mar
Inches | Inches | Inches | Inches | Inches | Inches | Inches
DB eG ee Te SN eel eine 0.00 222 Byes) 3.64 5.76 Ba 7All 4.85
USPS SS Gh aa i a .00 1.63 SOD, 1.56 3.6%) | 1-20 DAT,
MRO eae .00 Pay lee .10 5.16 3h Pe 7.08 4.58
MOB oom Af ae .00 .03 .50 6.23 5.99 Th TAD) 8.69
MOR eee ee deals ht 34! Lait Wl 1.28 2.87 2.50 2.89
Ol A Oe he es ent 1.28 86 .03 64 9 94 5.87 Phen s)
OA Asliire mses nk Re BIR a .00 1.56 .10 8.26 3.68 7.50 2.76
GSE Te cain Sea .00 eal 121 8.11 2.93 2.06 1.98
i GVA se Ig ence Mee .00 .00 1.98 Dini 4.63 Dele 5.09
SE AA iya sete) ar, sae 1T 123 56 Died, DitAS Ald 1.05
eed iti cease tame ot .05 1.05 4.98 2.83 ail 4.48 4.56
OA Ores eh un ayy 07 1.69 1.46 3:83 91 2.02 3.26
DANG ANT 22 ere aS eae ae .00 1.58 4.26 3.88 Ol Leal 94
MAY GAS ble ten n epee ents a, 28 1.64 68 83 .06 ey A Dil,
TAS Vear Mean: sas tio a 13 | 1.23 1.47 | 3.63 | 3.357] 4.538 3.54
12-month

Year Apr May June July Aug. total

Inches | Inches | Inches | Inches | Inches Inches
TG LR Ss iors i es ae Gage 6.33 0.00 0.00 0.00 0.00 29.40
IGE SY Girt SE i aia es So AS 04 .06 .00 22.65
MOS Ge Ole ee de ora ey 65 .00 .00 .00 .00 22.96
MOBS ai cae abr aie ea 2.69 02 .00 .19 .00 32.09
TORE ON aah ky ke 26 03 14 00 02 12.25
HVS GEA (Sie a loa! USM aS a ha ica Fo .43 .00 .02 .00 .00 222
HAS Aa sees ea Me 4.44 .02 .00 .00 01 282 30
OE AD ttaetinn Petia one i 2.81 Eso .00 .00 .00 21.54
OA ZEA pias imipeheciin eihs Sty Le 17 .00 .00 .00 .00 17.24
QAO eset esl ed Se Sn a ena 1.78 58 04 .00 .00 13.79
QAI TIN Se oe en H32 e335 .05 T 01 18.99
QA GS Sa ae oath Bl .06 56 .00 T .00 13.86
AG = Aen cee eet ees 44 Way .03 .00 .00 13.72
DRA ed Scare ass nee ec 4.13 1.26 01 .00 .00 14.50
i4-year mean________ 1.92 sD .02 .02 TS 20.18

1T =trace.

Air temperatures, relative humidity, and wind movement were measured
at a standard Weather Bureau station at the headquarters, at an eleva-
tion of 1,050 feet. Precipitation was measured as an average of readings
from two standard rain gages, one at headquarters and one at a rainfall-
runoff station in pasture 7 at an elevation of 1,100 feet. The records of
precipitation and air temperature are summarized in tables | and 2.

8 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

TaBLE 2—Monthly mean air temperature at San Joaquin Experimental
Range, November 1934-August 1948

Year Sept. Oct. | Nov. | Dec. Jan. Feb. | Mar.

°F We: pe whe 10: dae oie
OS 4 ne 0 Vila h His melo Nt ene vt eG [Net payin 52.1| 45.1 | 44.5 | 47.4 47.1
LOS DBO 2 eee naa kaa 1623) | 70000 0 473 We 448) 47 Os ASeo 54.3
JU) Genoa ign le i FOVO NS O47 |> ONT AD Se Soe ae 4 oa 51.4
OST SO aes tary ply Wie Rote eae M3 a0. | (6404 er o2 1 le 4G ble Ase Oi 4 sa3 48.5
BOS SOO es One ae we T5207 GOR2) | 47 On ly Ao 2a 42s lee 51.5

13 OAC ety ee Sans aan (4.5 16092) 1% 52,9) | ALS. 46 onl 4920 53.88
QA QS Arey Ae eae tS 68. 46128) 4800) cave = AG om peoO me 53.19

OA AZ Ones ETE eee 67.4 56.8 50.0 44.5 44.2 44.2 48.9
ING eC Ge Rr ed apn) O94 OT 427 42 Sea il ea ek 51.8
je ayes 2 El ae Min eS) Sepa oe 13: On OONS Ge VOU Ria | 4 ouO e442 aa 50.3
M4 Are Pann ce our US E38 17 O30 90) PAS {Gulls 45 coal (Ale ae Ayes 46.8
NO RA One or hea nope tee (3d Oo) (630-5049! Oy 45) OF E240 ba 4a 49.1
OA G4 ie ieee ent Ade Sollee (OR ae ce ein eRe aye le oa.) 53.3
UO A 4 Siena hs te Sak wala ane tle (4.8: Ol Ae Al OT A0no a aoa 4589 46.5
14-year mean______- D2 Oe te Olli, 49.3 44.7 | 43.0 | 46.6 50.5
12-month

Year Apr. May June July Aug. mean

Wee He 1a 21: °F. °F
EQS AT BO Be a Ne ier iaaS he 56.0 65.0 17.5 79.9 82: 20 |23
[OB Yo sa X) eee me ca eat Een Ve 60.0 68.4 76.6 84.7 83.5 62.7
POS Gee eer 56.1 69.0 19.6 84.5 82.5 61.3
ILC A ASCH aa peor Sue neers 55.9 66.4 LOVE 82.9 80.0 61.6
Jt pave aie uiuupaacliay Ciamtlns Jikan 61.5 67.1 USAT 81.9 81.5 61.0
TOSIEA Ole ely ero eins 58.1 69.1 Mf 78.5 78.6 62.3
TOAQ AeA Sens once knit eues 53.8 66.2 70.9 81.5 75.4 60.3
OAS A Dwbane rea olay nie mala 54.0 60.4 i2eel 81.6 79.0 58.6
OA DSA Se Ee RG a Lan 56.9 65.5 67.2 78.4 74.1 58.9
1943-44 nee 53.1 65.6 68.9 79.1 78.0 59.4
A Ad yea Men oa ape Nair tt 56.6 62.6 74.0 84.1 Phtoi acs 60.2
AAO eee rel taint atany 58.8 64.6 (ley 1M 79.5 59.9
1 CG a ys para UE 58.8 10-2 74.0 76.9 75.4 59.2
A eA Sak Tae SE yi ea 54.3 60.1 72:3 78.1 76.1 58.2
14-year mean________ 56.7 65.7 (eats 80.8 78.9 160.3
|

1 13-year mean.

The relative degree of herbage utilization — for example, close, moder-
ate, or light — in each of the six grazing-intensity pastures was rated each
year according to the amount of unused herbage left on the ground.
Ratings were made after the cattle were removed from the pastures, but
before the start of fall rains. The method used was to compare the grazed
range with standard photographs showing how the range looks with
different amounts of unused herbage.

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 9

To help determine how different degrees of use affect the condition
of the site, in January 1943 the depth and weight of the litter on the soil
surface were measured and correlated with the height and yield of new
herbaceous growth on 100 quadrats in each of pastures 1, 2, and 3.
Many other observations on litter conditions, soil erosion, and plant
growth were made at the experimental range and other parts of the foot-
hill area.

Cattle records taken included weights and forage preferences. Each
animal was weighed several times: When removed from one pasture
to another, at the start of the supplemental feeding period, just before
calving, at weaning time, at the end of the green-forage period, and at
other times when forage changed noticeably in quality or amount. In
the first years of the experiment the cattle were weighed soon after
watering in the corrals, but later they were shrunk overnight in a dry
lot before each weighing to minimize the differences in “‘fill’’ of water
and herbage at different times of year.

The manner in which the cattle selected the various plant species
at different growth stages was determined by observation of grazing
habits and of grazed vegetation. In 1936, R. H. Klugh ® recorded
detailed observations on the preference of cattle for the different plants
during the spring. During 1936-40, Kenneth A. Wagnon, resident
animal husbandman in charge of University of California cattle-manage-
ment studies, at daily or weekly intervals collected samples of the forage
that cows were grazing. ‘These samples were analyzed for chemical
composition. Other observations on use of the vegetation by cattle
were made during the course of the studies by other technicians.

FITTING RANCH OPERATIONS TO FORAGE GROWTH

Foremost among the results of this study is a clear understanding of
the seasonal growth of foothill forage plants. The availability and
nutritive value of the plants, and the species selected by cattle, change
during the year as the plants progress through different stages of develop-
ment. At certain stages, the need for supplemental feeds is critical.
Knowledge of these changes is basic to skillful fitting of ranch operations
to forage plant growth — and hence to efficient use of the annual-plant
cover.

AVAILABILITY OF FORAGE DURING THE YEAR

The characteristic California foothill climate results in three rather
distinct plant-growth periods (fig. 4). The first period usually starts in
October. Seeds of annual plants start to germinate after the first rains
of 0.5 to 1.0 inch. This amount is enough to start germination over most
of the range. After the first effective fall rains, however, plant growth is
often limited by insufficient soil moisture, unfavorable temperatures, or
both. In November mean air temperature for most days of the week
usually drops below 50° F. After this, growth is retarded regardless of
soil moisture. Plants grow intermittently, during short rainy periods
or other occasional periods of mild weather. Cold, dry weather with
frequent frosts that stop all growth or freeze back part of the plants can

5 Formerly Junior Range Examiner, California Forest and Range Experiment Station.

10 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

be expected for a few weeks each winter. Hence new green forage is
uncertain and not adequate to maintain cattle weights during this entire
fall and winter period.

The second period starts by late winter, usually about February 1.
At this time the green forage becomes adequate to maintain cattle
weights for the remainder of the winter, even though temperatures are
still too low for rapid plant growth. During the first early spring weather,
when mean temperatures for most days of the week are near 50° F. or
above and frosts are infrequent, plant growth is accelerated and green
forage begins to grow faster than it is grazed. Later in the spring,
usually in April, the temperature rises rapidly and there is a surge of
plant growth. Ordinarily most of the plants mature and dry early in
May, but a limited amount of herbage remains green for a short time
longer.

6 90
DRY INADEQUATE ADEQUATE
FORAGE GREEN GREEN FORAGE
FORAGE

PRECIPITATION (INCHES)
AIR TEMPERATURE (°F)

SEPT. OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG.

Figure 4.—Relation of the three yearly plant-growth periods to monthly precipitation
and mean air temperature, San Joaquin Experimental Range (average 14 years,
September 1934-August 1948).

By early summer the third period has begun. This is usually in June,
when almost all of the plants have dried. The little remaining green
leafage is on scattered plants of summer-growing annual species, or
perennial bunchgrasses. Most of the cattle forage is dry herbage until
fall rains bring new plant growth.

UNCERTAIN GREEN FORAGE IN FALL AND WINTER

The forage preference of cattle shifts from dry grass to the new green
plants soon after the seedlings emerge. The new plants are selected
when barely one-half inch in height, but cattle are forced to take some
old dry roughage as they search for the short new growth. This green

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 11

forage they take without discrimination between species. As most of
the plant growth occurs during short rainy periods, cattle obtain the
greatest amount of green forage immediately following rains. In years
with limited fall precipitation or with dry, freezing weather in the winter,
for several weeks at a time cattle must depend largely on the old roughage
whose value has been lowered thr ough leaching. Because growth of new
plants during the fall and winter is so uncertain, it is advisable to have
sufficient old grass on the ground in the fall to serve as a source of roughage
in the years when it is needed.

Supplemental feeding is necessary in this period of uncertain plant
growth. After rainy periods the crude protein in the cattle diet may be
above 10 percent; but when new plant growth is retarded and the cattle
are forced to eat more old roughage, the percentage of crude protein is
lowered (72).6 Also, throughout the fall and winter the total intake of
dry matter is reduced because the cattle spend most of their grazing
time in search of succulent green forage. Thus, supplemental feeds are
needed to supply both protein and carbohydrates. Inadequacy of the
forage alone was shown by weights of yearling heifers that did not
receive supplemental feeds. As an average for 12 years the heifers
weighed almost the same at the end as at the start of this fall-winter
period.

2 a
Roy LLMiyytyyys grey

(111//
Gy JILL

SEPT. OCT. NOV. DEC. JAN. FEB. MAR.

Figure 5.—Variations in length of time that green forage was inadequate on foothill
range.

The length of time that green forage was inadequate during each
plant-growth season at the experimental range is shown in figure 5.
Start of the period of inadequate green forage was closely related to the
date of the first effective autumn rains of 0.5 to 1.0 inch, or more. End
of the period is the date when cattle were placed in the grazing-intensity

® Italic numbers in parentheses refer to Literature Cited, p. 51.

12 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

pastures, except for 2 years when end of the period was estimated from
climatic records: 1935, the year before pastures were stocked, and 1937,
when cattle were placed in them about 6 weeks too early.

The starting date for this period, for all 14 years of study, averaged
October 24, but differed considerably from year to year. The interval
between germination of seed and restriction of plant growth by low
temperatures averaged about 3 weeks but varied from 0 to 76 days.
Green forage produced during this interval was not sufficient in any year
to maintain satisfactory cattle gains during the entire fall-winter period.

In some years, however, forage growth after early rains was sufficient
to produce gains of cattle early in the fall. For example, in 1939 — the
year with earliest effective rainfall — there was a good start of forage
growth after a total of 1.97 inches of rainfall between September 25 and
October 7, and the unsupplemented yearling heifers gained in weight.
Later, during a drought that extended into January, plant growth was
stopped and many plants died. The unsupplemented heifers stcpped
gaining in weight, but they ended the fall-winter period with a net gain
of about 40 pounds each.

There was considerable variation in plant growth and cattle gains
in other years, but the poorest fall growth of forage occurred during the
1937-38 and 1943-44 seasons when the first effective rains occurred late
in the fall, after mean daily temperatures were below 50°. In these two
seasons the unsupplemented heifers lost about 20 to 25 pounds each
during the period of inadequate green forage.

Poor growth of forage in the fall also means that green forage will not
be adequate in amount until late in the winter. For example, in the
1937-38 and 1948-44 seasons, feeding of supplements was needed until
late February or early March.

Even when good growth of forage occurs in early fall, the end of supple-
mental feeding cannot be predicted with certainty. Cold weather during
the winter, often coincident with dry weather, may halt plant growth
before the green forage is adequate in amount. Also, part of the avail-
able forage may be frozen back after being judged adequate, making it
advisable to resume feeding. ‘This happened in two of the five years
when feeding was terminated before January 15. However, there seems
to be little likelihood of prolonged forage scarcity when supplemental
feeding is terminated in February.

DEPENDABLE GREEN FORAGE IN SPRING

The period of most dependable forage is approximately 4 months long,
from January or February into June. During this period the vegetation
develops from early-leaf stage through seedstalk, flower, and mature-
fruit stages. In these stages of plant development the mixed cover of
many plant species provides an adequate amount of well-balanced cattle
forage. |

Several signs can be used in late winter to judge when green forage is
adequate in amount. The grasses average 2 to 3 inches high but are
considerably taller under trees or in other areas where conditions have
been favorable for plant growth. Some plants of early-growing species
such as slender oat may be 6 inches high or taller. Fuilaree is 1.5 to 2.0
inches high on the average and considerably taller on small spots. Young
animals usually will have started to gain in weight when the forage has

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 13

GU 11111 /
S/S) /// AS //111117/ 0

| ALLY, YY fj i

FiGguRE 6.—Variations in length of time that green forage was adequate on foothill
an

reached this height. Cattle often will stop coming in to feed when called.
This, along with height of vegetation, can be used in deciding when to
quit feeding supplements.

The period of dependable green forage (fig. 6) extended until approx-
imately the date when the crude protein content of the forage eaten by
cattle dropped sharply below 9-10 percent. For 1936-40 the final date
was estimated from the forage samples collected by Wagnon; for other
years it wasestimated from observations of plant development. The
length of period was judged on conservatively stocked range.

Forage preferences of cattle change several times during this period.
In late winter cattle continue to graze the different plant species without
discrimination wherever they are tall enough to be grazed. All species
can still be considered as forage. Most of this forage is provided by the

scattered spots of taller plant growth. Such early-growing species as
slender oat, ripgut brome, Douglas fiddleneck, and popcorn-flower are
taken in considerably quantity. Taller plants of filaree also are grazed.
The forage in the early leaf stages is rich in minerals and protein, the
crude protein content usually ranging from about 20 to 30 percent (J, 3).
Cattle start to gain in weight even though the vegetation is still short.

When plant growth is accelerated by rising spring temperatures, cattle
still graze most species, but the widely available and early maturing
subspecies of broadleaf filaree (11) provides the bulk of the forage.

14 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

With the midspring surge in plant growth, cattle become more selective.
Many of the forbs (broadleaved herbaceous plants) are discriminated
against after they flower and are no longer good forage plants. Of the
species selected by cattle, soft chess and the late-growing species of
broadleaf filaree are the most abundant and in most years provide the
bulk of the forage. Seed heads of soft chess, which mature in late spring,
are especially sought out in years when heavy heads are produced. The
annual grasses and perennial rushes on bottom lands are heavily grazed.
The clovers, which make most growth in April or early May, are greedily
taken wherever they occur, and in “‘good clover years” furnish a large
part of the spring forage eaten by cattle. During this time of rapid
growth, there is an abundance of green vegetation in several stages of
development, from full leaf to mature fruit. The forage selected by cattle
is well balanced nutritionally, and the most rapid gains of cattle are made
at this time of year. Gains of yearling heifers that had not been supple-
mented during the winter usually ranged from 2 to 2!4 pounds per day.

After the herbaceous vegetation starts to dry, cattle can still find an
adequate amount of green forage for several weeks. Early maturing
species start drying on south slopes by the middle of April in most years.
In years of low rainfall drying will start in March, or even as early as
February, and the south slopes will have a mottled yellowish-green
appearance by the first of April. But the bulk of the herbage does not
dry until temperatures rise sharply and the upper soil dries. Then most
of the herbage may dry within a few days. This rapid drying usually
occurs early in May, but may occur during the last half of April in years
of limited late spring precipitation, as in 1939, 1946, and 1947.

Cattle become quite selective in their search for green vegetation at
this stage of the spring period. Grazing is concentrated on soft chess,
filaree, and littlehead clover on the lower slopes and on whitetip clover,
toad rush, grasses, and perennial rushes in the drainage bottoms. Cattle
also make considerable use of the green plants under trees; and of the
scattered green plants such as late-flowering godetias, summer-growing
Spanish-clover, and yellow-tarweed. By such selection cattle can obtain
an adequate amount of nutritious green forage for 2 to 6 weeks after the
bulk of the range herbage has dried.

In June the cattle are usually forced to graze largely on dry herbage.
The crude protein content in their diet drops below the level considered
necessary for maintenance of mature cattle. This may occur in May —
as in 1939, 1944, 1946, and 1947 — when the supply of late growing species
is limited by light total annual or late-spring rainfall. In years of heavy
annual and late-spring rainfall (1935 and 1938), adequate green forage
is available until late in June. The yearling heifers continued to gain in
weight after they were eating considerable dry herbage, but the rate of
gain dropped rapidly during June.

DEFICIENT DRY FORAGE IN SUMMER AND FALL

Cattle are forced to graze almost entirely on dry forage for about 5
months during the summer-fall period (fig. 7). Most of the forage is
from dry annual grasses. These provide a roughage high in carbohydrates,
but they usually contain less than 5 percent crude protein (1, 3). A
supplemental feed is needed to supply protein. Heifer calves weaned in

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS ile)

July and not fed supplements usually gained slowly for part of the
summer dry-forage period and lost in weight by the end, the net change
being a few pounds loss on the average.

The most abundant of the finer-stemmed grasses, soft chess and foxtail
fescue, are the most widely grazed. Soft chess is the most valuable of
the annual grasses at this time because it retains a considerable amount
of unshattered seed. Other small grasses and toad rush are also selected
but may be limited in amount. The coarser grasses, such as wild oat
and ripgut brome, are less readily grazed after they have dried.

Most of the forbs are of little value after they dry and crumble. Many
have coarse, fibrous stems, such as those of the broadleaf filarees, and
are not grazed unless cattle are forced to eat them because of a shortage
of preferred roughage. Native clovers, redstem filaree or alfileria, and
bur-clover are exceptions. The fine-stemmed native clovers have a
higher protein content than most dry annual species and are sought by
cattle even after the plants start to crumble. Redstem filaree has the
highest protein content of any filaree and is often grazed closely after
it dries. Mature dry bur-clover, with its nutritious burs, averages about
15 percent protein, an amount more than necessary to meet minimum

SERS pe PaSE ING aT AN a ere Yaa is a
7] //////)//////// rz
=| £[{f{{f{{{YUYYYY{IIILIIL
°° | VILLA LALA hsp Ys pllhli
| LI

1941 Vf,
7 /////,

© LDQ LLL «~~
1948 ALL --'ee
1947 lf, f, ‘|
°° £%QGhKGHTTHHTTT7??.......

MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC.

AVG.

Figure 7.—Variations in the length of time that cattle grazed almost entirely on dry
forage on foothill range.

requirements of cattle (2, 3). Because it serves as a protein supplement
to the other dry plants during the summer and fall, when present in
adequate quantity, bur-clover is the most valuable of the annual plants
on foothill ranges.

Vitamin A deficiencies may also occur on dry annual-plant range
where there is no browse. Phosphorus deficiencies, which may occur in
the natural forage, will usually be met by use of concentrates as supple-
mental feeds (12).

16 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

SUPPLEMENTING RANGE FORAGE DURING CRITICAL PERIODS

Although best adapted for grazing during the approximately 4 months
of adequate green forage, foothill ranges are of necessity grazed at other
times of the year. Only a limited acreage is used solely in the spring,
when the forage would promote most efficient livestock gains. The
foothills are the chief source of range forage during the fall and winter.
In many operations the livestock are kept on these ranges during the
entire year. Whenever foothill grazing extends beyond the green-forage
period, the natural range forage is now commonly supplemented during
part or all of the time that it is deficient.

A practice of supplementing foothill range forage was developed by
the Division of Animal Husbandry, University of California, in their
part of the studies at the San Joaquin Experimental Range (2, 13).
Here, where there is little bur-clover, the practice is to feed 1 pound of
43-percent cottonseed cake per day per cow while depending on dry
range forage during the summer. ‘This amount is increased to 11% to 2
pounds per day in September or October (before the start of calving),
after the better forage species have been removed by grazing through the
summer and fall. Rolled barley, at 1 pound per day, is added as a source
of energy-producing carbohydrates after the first effective fall rains.
Supplements are decreased gradually as new green forage becomes more
abundant in late winter. The daily amount of feed is increased slightly
in years when there is a low proportion of grass and clovers, when the
dry forage is leached by late spring rains, or when cattle weights are below
average.

Ranchers must also take into account the year-to-year variations in
the length of the period with adequate green forage. During 14 years
of study the average length was 127 days, but the period varied from
72 days in 1944, 43 percent below average, to 176 days in 1935, 39 percent
above average. Variations between 15 to 30 percent above or below
average occurred in four other years. For operations in which cattle
are moved onto foothill ranges during the winter and moved off in late
spring, the variations can be met by purchasing supplemental feeds,
moving to other sources of range forage, or varying the date of buying
and selling stockers and feeders. For operations in which the cattle are
on foothill ranges the entire year, or from fall until late spring, such
variations can be met only by supplying sufficient feed to supplement
the deficiencies in the natural range forage.

How the amount of supplements needed may differ from year to year
because of variations in the forage crop is suggested by records at the
experimental range. Supplemental feeding was started several weeks
later than desirable in some years because the cows to be supplemented
were mixed with unsupplemented cows in the grazing-intensity pastures
until about August 1. Nevertheless, for 10 years (1937-46) the yearly
supplement per cow varied from 288 to 462 pounds (13).

Supplements increased cattle production. Averages reported for the
first 7 years (2) show a calf crop of 83.0 percent for the herd fed supple-
ments and 67.6 for the herd not fed supplements; calf weaning weights
at about 8 months of age were 470 and 417 pounds, respectively. An
average of 365 pounds of supplemental feed yearly produced 108 pounds
more calf weight per breeding cow in the supplemented herd.

=a a Fah

- USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 17

Thus, although green forage is adequate only about 4 months, foothill
ranges can be efficiently grazed during the entire year, provided there is
sufficient dry roughage on the range and supplements are fed during the
time when the green forage is deficient in quantity or quality.

Ranchers follow several practices to supplement range forage. Dry-
land Sudangrass is used in connection with some foothill ranges during
the summer. As pointed out by Jones and Love (8), this practice is
centered in the Sacramento Valley and Coast Ranges and is limited on
most ranches by the small acreage suitable for dry-land farming. Another
practice is to mow green range vegetation on part of the ranch and to
feed the hay out of the windrow or shock during the summer. ‘This
method is usually limited to areas that support a good cover of wild oat.
Alfalfa hay, or home-grown grain or wild-oat hay, is used as a supplement,
occasionally in the summer but more commonly in the fall and winter.
Probably the most widespread practice is to feed protein concentrates,
particularly cottonseed cake, during the fall and winter — and on some
ranches during the summer, too. The cooperative animal husbandry
studies have shown that supplementing the dry range forage is an efficient
range husbandry practice.

LENGTHENING THE PERIOD OF ADEQUATE FORAGE

A major objective in foothill range management is to devise practices
that will provide adequate forage for livestock over the longest possible
period. Cultural treatments of the land, such as range reseeding or
fertilization, have been used successfully on a trial basis to accomplish
this objective. Adapted perennial species established by seeding will
produce adequate green forage earlier than annuals and will provide
some green leafage during the summer. Also, an increase in production
of annual legumes will lengthen the period when foothill range forage is
adequate. For example, studies now under way at the experimental
range have shown that sulfur-bearing fertilizers will increase native
annual legumes on these granitic soils. As a result, yields of dry forage
are increased and its nutritive value during the summer is greatly im-
proved, and forage growth during the following winter is stimulated
because of the nitrogen added to the soil by the legumes. Cultural treat-
ments to increase soil fertility and establish superior species, combined
with management to make best use of the improved range will be more
widely used to lengthen the period of adequate forage on foothill ranges.

Results of this study, however, show that there are other means of
providing green forage at times when it is critically needed. This can
be accomplished on some ranches by using the different kinds of range
land at the best time of year. For example, in the early part of the plant-
growing season, north slopes are better suited for grazing than south
slopes. This is especially true of the steeper north slopes where the soil
surface dries slowly after the infrequent rains at that time of year.
_ Hence, the tallest green forage is found on north slopes. Similarly, new
_ green forage is often more abundant in the shade of some tree and shrub
canopies than in the open. ‘These effects of shading are particularly
important in years when fall-winter rainfall is below average.

By late winter soil moisture is ordinarily not a limiting factor, and the
situation is reversed. At this time plant growth is most advanced on
warm south slopes; green forage is usually adequate, without supple-

18 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

TABLE 3.—Comparison of herbage per grazable acre from swales and slopes
in pasture No. 2, San Joaquin Experimental Range, during four specified
years 1

19438 1944 1945 1948
Plant group | DE ies, aera ee
and species

| |
Swales | Slopes | Swales | Slopes | Swales | Slopes | Swales | Slopes

|
| | | |

| |
‘Pounds Pounds Pounds |Pounds |Pounds |Pounds Pounds Pounds

Grasses: | |
Soft chess___ Q7 825 151 485 182 Silt 80 35
Foxtail |
fescue ____ 552 | 205 499 181 919 269 760 | 101
Mediter- |
ranean |
barleys=22))2,5425) 44 Babin LCG AL 5 | 1,683 Av 641 At
|
Other | |
grasses____| 94 137 69 173 126 140 36 | 138
‘ota lee se | 3,285 PGir 25540 844 | 2,910 940 | 1,517 374

Grasslike plants:

Toad rush. _- 56 a 10 At 14 At at a
Perennial
rushes____ 381 | a 232 3 632 A Bon At;
Ao Galena ewe A Sian aD | 242 | 3 646 At 33. | ap
Forbs: | |
Filaree_____ 128 | 707 204 421 408 622 610 877
Clovers._.__| 258 | 642| = 112 16 | 1,004 |. 121 32 23
Other |
legumes. __| 11 | 82 18 39 79 158 4 78
Other forbs. _ 263 110 | 165 87 579 278 33 27
Motaleves. | 660 | 963 499 563) 2,160) |. 11-79 675 1,005
All species_____- | 4,382 | 2,130 | S081 AO SG 2a Oa see 20 | 1,379

1 Based on sorting and weighing of herbage clipped at 14-inch stubble height in
May on about 100 temporary, protected quadrats on swales and 100 on slopes during
1943-45 and 50 on each site in 1948.

2 T =species or plant group occurred as a trace or was not found in the sample.

ments, about one month earlier than on the steeper north slopes where
the soil may be frozen during the coldest weather. South slopes, however,
are not well adapted for grazing in late spring since the plants dry early.

Another means of using different kinds of land at the best time is to
defer the grazing of some swales until the supply of green forage on slopes

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 19

is nearly exhausted. Swales are the last sites to dry, and most of the
herbage produced on swales remains green for 2 to 4 weeks longer than
the bulk of the vegetation on slopes. Late-maturing species growing on
the swales (table 3) help extend the green-forage period there. The late-
growing annual clovers, mainly whitetip clover, and two perennial grass-
like species, common spikesedge and slimpod rush, produce a heavy crop
of forage in most years in the wet swale bottoms. Mediterranean barley
makes a heavy growth on the drier swale borders; foxtail fescue, which
dries a little earlier, also produces considerable herbage on this site.

Some large swale areas can be fenced; but if this is not practical, many
foothill ranches will be able to defer use of entire range units that contain
a high percentage of swale sites. Such lands also usually contain the
sites that support the best growth of Spanish-clover and other late-
maturing slope species. Because of the relatively high production of
swales, it should be beneficial to defer even small acreages in order to
provide some additional green forage at the end of the green-forage
season.

The practice of deferring swales has other advantages, too. Cattle
can select the choice forage species and have an improved diet when
turned into such deferred range pastures. Thus, even when experimental
herds were moved from grazing-intensity pastures to ungrazed range
in August, crude protein in their diet increased for a short time after the
move (12). Also, deferring swales until the soil is no longer soft should
reduce soil compaction and increase herbage production.

Several consecutive years of less-than-average precipitation, however,
may greatly reduce the extent to which the green-forage season can be
lengthened by deferring grazing in swales. ‘The accumulative effect
from a shortage of soil moisture in swales is a decrease in production of
late-maturing species. This change was observed in 1947, after low
rainfall in 1946 and 1947, and was very pronounced in 1948, another dry
year. The clover and the rush portions of the total swale production
in pasture 2 had each dropped from about 10 percent, as an average for
3 years (1943-45), to about 1.5 percent for each in 1948. Yield of clover
dropped from 488 to 32 pounds per acre, and yield of rushes from 442
to 33 pounds per acre. Deferring use of swales, however, may be desirable
during a period of several dry years since even a small increase of green
forage is especially helpful under such conditions.

Still another way to lengthen the green-forage period is to promote
earlier fall and winter growth of the annual plants. This can be done
by grazing management that leaves sufficient unused herbage on the
grounb, as is shown later by results of grazing-intensity tests. On con-
servatively stocked range, green forage will become adequate 2 to 6
weeks earlier than on heavily stocked range.

ADJUSTING RANCH STOCKING TO HERBAGE
PRODUCTION

Each ranch contains range land with different characteristics of soil,
topography, brush cover, and rockiness. These characteristics influence
not only time of forage growth, but also total herbage production. More-
over, production of annual-plant species varies considerably from year
to year because of differences in weather. By a skillful adjustment of

20 CIRCULAR 870, U. 8S. DEPARTMENT OF AGRICULTURE

ranch stocking to these variations, efficiency in use of forage can be
increased.

EFFECT OF SITE ON GRAZING CAPACITY

Classification of the different kinds of range land will aid in making
the necessary adjustments. For example, on granitic soils — such as
those in the experimental pastures — herbage production is usually greater
on the more gentle slopes, apparently because the soils are deeper and
finer-textured than on steeper slopes. Obviously, this difference will
affect the grazing capacity of the land, and a means of classifying the
range according to such differences will improve the estimation of grazing
capacity.

In evaluating the grazing capacity of the experimental pastures, it
was found that the land could be separated into six readily identifiable
site classes. These are:

1. Swale.—The swale (drainage bottom) soil is typically a dark grey,
sandy clay loam with a fairly good water-holding capacity, as contrasted
to the shallow, brownish, sandy loams of low water-holding capacity
that are found on the slopes. The swales receive a considerable amount
of seepage water; in wet winters some portions remain saturated for
several months. Swales (figs. 8 and 9) consist of a heavy, poorly drained
phase, or wet swale, and a lighter, better-drained phase, or dry swale,
that usually borders the wet swale.

F—395852
Figure 8.—Narrow, ungrazed “wet swale’’ with exceptionally dense stand of perennial
rushes, April 1940.

2. Gentle slope-—Located just above the swale, the fine sandy loams
of gentle slopes represent the transition from transported soil in the
drainages to soil developed in place on the slopes. Gradient is under 10
percent.

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS Dt

F—302874
Figure 9.—Exceptionally heavy growth of whitetip clover in ungrazed swale, April
1935. Dense stand (near backboard) in wet swale and thinner stand at left in
dry swale phase. Grazing capacity of swales in the grazing-intensity pastures
is 0.5 to 0.7 acre per animal-unit month. Grazing capacity of the narrow border
of gentle slope around the swales is 0.8 to 1.1 acres per animal-unit month.

F—460563
Figure 10.—Rolling slope with only occasional trees, shrubs, or rock outcrop. Grazing
capacity of this kind of range land is 1.25 to 1.75 acres per animal-unit month.

DD, CIRCULAR 870, U. 8S. DEPARTMENT OF AGRICULTURE

3. Open, rolling slope—rThese sites, with a gradient of 10 to 25
percent, have an open cover of trees and shrubs and only scattered rock
outcrops (fig. 10). Most of the sandy loams are about 24 inches deep.

4. Rocky brushy, rolling slope-——The average gradient of these sites
is greater than for the open, rolling slope but the range in gradient, 10
to 25 percent, is about the same. In general, the soils are shallower and
coarser and more of the surface is covered by rocks, shrubs, and trees
(fig. 11). Such lands comprise more acreage than any other site class
within the area of granitic soils.

5. Rocky brushy, steep slope—These sites have a gradient of 25 per-
cent or greater and numerous rock outcrops or many shrubs and trees.
The steep areas are not common in the lower foothills; they differ con-
siderably from place to place, including some productive soils as well as
thin, sandy soils.

6. Steep, rocky bluffs—These localized areas are small in size and
practically unused by cattle.

F—375364
Slope with common occurrence of trees, shrubs, or rock outcrops. Graz-
ing capacity for most of this kind of range land with rolling-to-steep slopes is from
2 to 3 acres per animal-unit month.

FIGURE 11.

The relative herbage production of each site class was estimated from
yield measurements made in pastures /, 2, and 3 during the period 1943-45
(table 4). The yield from the best site was almost nine times that from
the poorest, and the differences between sites are evidence that the grazing
‘apacity of foothill ranges is related more closely to the sites than to the
total acreage of the range unit. Steep slopes were not well represented
within the sampling areas, but though not precise the yields estimated for
the steep-slope site class are considered indicative of average production
on such sites. The differences in yield between north and south exposures
were determined from observations extending over 10 years. On north

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 23

TaBLeE 4.—Relative herbage yields of site classes, San Joaquin Experimental

Range
Yield per | Grazable | Yield per
Site class grazable soil 2 surface
acre | acre 3
Pounds Percent Pounds
‘Shegend es 9 Se ak 4,400 100 4,400
Gentle slope:
INOTGhivexXpOSsUTe ee so LoS ee 3,200 95 3,040
SOULMexpOSUKe=s.2 Ho Mun as a 2,800 95 2,660
Open, rolling slope:
INorthtexposunes auld? sj! Soo) ee 2,200 90 1,980
SOupnee xpOsuTemEes aL ee 2,000 90 1,800
Rocky brushy, rolling slope:
INonthsexposunese sae Br 1,400 70 980
DOMUMBeXPOSUTe Meee ek 1,400 70 980
Rocky brushy, steep slope:
INOTthRexMOSURE eh ere a oe 900 55 495
SOULMVeXMOsUTeteemanr Sa Se 1,800 70 1,260
DUCCMeLOCky, DiUiicemmemn aN Rou ee 8 A ay a ON

1In evaluating productivity of the several site classes, the average yield of 4,400
pounds per acre for swales in pasture 2 during 3 years of intensive sampling (1943-45)
was taken as a base. Yield of each slope site class and for steep slopes in relation to
the base yield for swales was estimated from a limited number of sample quadrats
for each site class in three pastures in 1945.

2 Percentage of grazable soil for each site class was estimated from an intensive
survey of the land surface actually grazable by cattle in each pasture.

3 Yield of herbage per surface acre (Land Office acre) was computed for each site
class by multiplying the yield per grazable acre by the percentage of grazable soil.

exposures on rolling topography, with thin stands of trees and shrubs,
yields were commonly observed to be greater than those on similar south
exposures. On steep north exposures, however, the stand of herbage
was often thinned by shading from dense tree canopies.

That productivity of range site classes must be taken into account in
estimating grazing capacity is also shown by the lack of correspondence
between size, productivity, and degree of utilization in each of the six
grazing-intensity pastures on the experimental range (table 5).

As a yardstick of productivity the acreage of each site class in each
pasture was reduced to its swale-equivalent in herbage production, or
“swale-acres.’’ Because pasture /, 154 acres in area, contained a rela-
tively great proportion of the more productive site classes (fig. 12), it
had a productivity equivalent to that of 60 acres of swale. But pasture
8, with 155 acres and a different combination of site classes, mostly of
lower value, was equivalent to only 48 acres of swale. Similarly, the
230-acre pasture 2 contained 12 more swales-acres than the 309-acre
pasture 4.

Each pasture was stocked with 15 cows along with their calves and a
bull for part of the season. This stocking averaged approximately 19
animal units per pasture for a 6-month season. Consequently, the two

24 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

Pad
(/ - : | a

fis || (GMM OPEN, ROLLING SLOPE

i” iy et Fil ROCKY BRUSHY, ROLLING SLOPE
rl £ mae : cl
D ins il “ly 1

EEE] ROCKY BRUSHY, STEEP SLOPE

Peers
es!

[__] STEEP ROCKY BLUFFS

. ‘yl My am nti
VY a ga

Wai
UY

(2 |

Zw
=

Vp: ; Va
Coa
44/7

Uy

ri GY Ut

Figure 12.—Map showing different kinds of land (site classes) in pastures 1 to 6.

ail

TABLE 5.—Pasture size, productivity, degree of grazing, and grazing capacity
on six pastures

Range Degree of
pasture Size | Procuctivity ! grazing Grazing
number obtained 2 capacity 3
Acres Swale-acres Animal units
os ube 0 aoa eb aaiceas 155 43 CTO SC er a Bea etree 12/3
1 bis Pes Cece Bes 154 60 Moderate to; close] 17a
Bypass Ra et Ay 3 250 68 Moderates: S25 ae Se re 19.4
7 ee aiegte PSUM Yi 309 78 >|) Light:-to:moderates==3-2 es 22.3
Gecer eto as tea 316 Cote Yuta cl Uri oy RRM an Le ANA Bal ee 25.4
Fp epee An 8 230 S) O Vaaray pete wo (onan ee re SR REA iret 25.7

1 Sum of the acreages of all site classes in the pasture after the acreage of each site
class had been reduced to its swale-equivalent in herbage production; based on relative
herbage yields shown in table 4.

2 11-year average obtained when each pasture was stocked with approximately
19 animal units for an average grazing season of 6 months.

8 The number of animal units that the pasture would support for 6 months under
moderate grazing.

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 25

pastures with the lowest productivity were grazed closest and those with
the greatest productivity were grazed lightest. All six pastures showed
a consistent relation between productivity and degree of grazing.

This consistent relation was also evident when the grazing capacity
of each pasture was estimated as the number of animal units that the
pasture would support under a moderate degree of grazing for an average
6-month season, from about February 1 until August 1. Stocking at
approximately 3.50 swale-acres per animal unit gave moderate utilization;
the range was from about 2.25 swale-acres for close utilization to 4.75
swale-acres for light utilization. Using a requirement of 3.5 swale-acres
per animal unit for 6 months, the 154-acre experimental pasture would
support 17.1 animal units under moderate grazing, and the 155-acre
pasture would support only 12.3 animal units.

The grazing capacity of each site class under moderate grazing was
calculated from the relative yields per surface-acre shown in table 4.
For example, swales with a yield of 4,400 pounds per acre and a capacity
of 3.5 acres per animal unit for 6 months required an average of 0.58
acre per animal-unit month. Similarly, south exposures on open, rolling
slope, with a yield of 1,800 pounds per acre, required an average of 1.42
acres per animal-unit month. Because of variations in productivity
around the average for each site class, a range in grazing capacity was
estimated for each. The estimated range in grazing capacity for each
site class was:

Acres per animal-

Site class: unit month
DSR iG oR TS a a fy Ap NS ec 0.50-0.70
Cremiblegsl Op emai Siar eir ss rane i lige Ue Nita Wiad i Mae AB .80-1.10
Owen Proilingeslopers ae eRe eh ee Fae ee eae 1.25-1.75
voc keypbrushyperollimeslopere tee hoa aCe uh an 2 .00-3 .00
Rocky orushyasveep slopese 28 ine tse ee ee es 3.00-5 .00

More refinement in criteria is needed for recognition of grazing capacity
on steep slopes, but the range in capacity for other site classes is sufficiently
narrow for satisfactory use.

The studies show that grazing capacity can be estimated by range
land classification. Thus range site classes are of direct use in determin-
ing proper ranch stocking. In addition, classification of range sites will
bring about more equitable evaluation of the tax base and more uniform
loan appraisals on foothill lands.

EFFECT OF ANNUAL PRECIPITATION ON HERBAGE YIELD

Records of how herbage yield on the experimental range fluctuated
with annual precipitation show the need for flexibility in stocking.
Total herbage production there is typical of other parts of the California
foothills where average precipitation is about the same or greater. On
soils different from the granitic soils of the experimental range, annual-
plant herbage presumably would respond in a similar manner, but the
amount of monthly and annual precipitation required for the same plant
response might be different.

The total yield at maturity of most species for each year (fig. 13) was
estimated as the average for all grazable soil in pastures 7, 2, and 3.
The estimates were based on intensive measurements made as follows:
1943-45, all sites in the three pastures; 1948, all sites in pastures 2 and 3;
1942, all slope sites in pastures 2 and 3; 1937-48, 14-acre exclosure in
pasture 7.

26 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

TOTAL PRECIPITATION
DURING SEASON

ae 12"—16"
F406 = 16"— 20"

14 ABOVE 20"

2,000

AVERAGE

YIELD
ae,

1,600

IS

1,200

800

YIELD PER ACRE (AIR- DRY POUNDS)

400

y
Z
y
Z
y
y
Z
y
Z
Z
Z
y
Z
y
y
Z
y
y
y
y
Y

CAAA

Ey
AY
AY
AY
AY
AY
AY
AY
AY
AY
AVY
AVY
AY
AVY
W
AZ,

EOC

- '38- '39- '40- ‘41- '42- '43- “44- '45- “46- ‘47-
4) “497 “43,445.45. 46> 4m 48
PLANT GROWING SEASON

FicurE 13.—Estimated total production of air-dry herbage per grazable acre, and
total precipitation during plant growing season (September of one year to time of
plant maturity in next year), San Joaquin Experimental Range, 1935-48.

In years with precipitation greater than 20 inches, the heavy rainfall
during the winter months was largely lost by seepage from the upper soil
before air temperatures became favorable for plant growth. Shallow-
rooted annuals could not take advantage of the excess precipitation
except on bottom-land soils, where ample seepage from the slopes pro-
vided moisture into the spring months. Thus, total herbage production
Was approximately average in four of the six seasons when total precipita-
tion was above 20 inches. Greater than average yields were obtained
during 1937-38, with 32.09 inches of precipitation, when good rains oc-

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS Dil,

curred late in the spring. Exceptional yields were also observed during
1934-35, not shown in figure 138, when precipitation totaled 29.40 inches
and good rains occurred in both fall and spring. In 1936-37, however,
yields were below average, even though precipitation totaled 22.96 inches,
apparently because severe winter temperatures stunted the plants so that
full production was not attained later on. Winter temperatures may have
more effect on plant yields than is readily apparent because effects of
temperature are not easily dissociated from effects of precipitation.

In 1942-48 and 1944-45, with total precipitation of 17.24 and 18.99
inches, respectively, soil moisture was considered adequate during the
winter and there was sufficient seepage into the swales to promote good
growth on these fertile sites. Yield in each of these 2 years was well
above average. ‘These years were near the long-time average of 17 to 18
inches, calculated from isohyetal maps of the U.S. Weather Bureau and
from comparison of precipitation records at the experimental range with
records of longer duration at other foothill stations. Apparently average
or greater yields can be expected in most years when total precipitation
at the experimental range is within a range of 16 to 20 inches.

In dry years, with precipitation between 12 and 16 inches, soil moisture
was not adequate at all times during the winter, and there was only
limited seepage into the bottom lands. Herbaceous vegetation was
retarded at some time during the winter or spring by lack of moisture,
and total yields were accordingly reduced. In each of the five grazing
seasons with total precipitation well below the long-time average, herbage
production was measured or estimated to be between 1,200 and 1,500
pounds per acre, as compared to the 13-year average of about 1,640
pounds. Often, half or more of the total herbage in dry years is pro-
duced after rains of 1 to 2 inches in late March or April, after some species
start to dry at a very short height. This ability to make rapid growth
during a short period of favorable weather in the spring allows production
of a fair total yield in years that are otherwise unfavorable, and enhances
the dependability of annual-plant herbage production. The critical
point of annual and monthly precipitation, below which annual-plant
production is reduced, will depend on the character of the soil. Observa-
tions indicate that plant growth is limited by below-average precipitation
to a greater extent on heavy, fine-textured soils than on lighter soils.

In drought years, say with less than approximately 12 inches total
precipitation at the experimental range, herbage yields would probably
drop below 1,200 pounds; but how far below is speculative: annual
rainfall was more than 12 inches throughout the period of study. In fact,
study of long-time records at other foothill stations indicates that pre-
cipitation at the experimental range may have fallen as low as 8 to 12
inches in only 6 years out of 48; and only two of these occurred in the
40 years from 1909 through 1948.7 Because the distribution of rainfall
in drought years ordinarily does not follow the normal pattern, some
drought years may have above-average spring precipitation and a fair
total production of herbage. To the knowledge of local ranchers, no

7 Monthly and annual precipitation at the San Joaquin Experimental Range for
period September 1897-August 1934 was computed from U. 8. Weather Bureau
records for Friant, Calif. (no record 1904-06), by regression equation based on correla-
tion of precipitation at San Joaquin Experimental Range and Friant during the period
September 1934-August 1946. Average annual precipitation at Friant was 13.24
inches for the period 1897-1945.

28 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

‘failure’ of herbage production occurred in the vicinity of the experi-
mental range from 1877 to 1948. In years of extremely low precipitation,
however, severe forage shortages undoubtedly occurred during a con-
siderable part of the plant-growing season, and a shortage of water for
stock limited effective use of the forage after it dried.

STOCKING TO MEET FORAGE FLUCTUATIONS

To meet the fluctuations in the forage supply and obtain efficient
utilization of annual plants, some adjustment in stocking is needed nearly
every year. Whether a change in numbers of livestock is needed can
be judged in late spring, after almost all plant growth is complete, and
again at weaning time in the summer or fall. The extent of adjustment
and the classes of stock involved will depend on the type of operation
at each ranch.

For ranches keeping the cattle on foothill range during all or most of
the year, the desirable flexibility can be had by operation of a breeding-
cow herd in which all or part of the calves are generally carried over and
sold at the end of the next green-forage season as long-yearlings. Essen-
tially, this practice consists of carrying enough cows and replacements
to utilize most of the forage in the years when yields are well below aver-
age. During the five dry years at the experimental range, total herbage
production was reduced a little more than 25 percent below average in
two of the years, but only about 10 percent below in two other years.
Probably the cow herd should not take more than 75 percent of the usable
herbage in average years.

The extra forage in years of average production is utilized by yearlings.
If there is no extra, the young stock can be sold as weaners. In years of
above-average herbage production the increased forage yield may either
be utilized by bringing in outside animals, or be left on the ground to
replace any litter than may have been lost during dry years.

If a year of very low herbage production occurs when maximum numbers
of yearlings are being carried, some animals can be sold earlier than usual
to save range roughage for use by the cow herd during the summer, fall,
and winter. Other adjustments can be made by heavier culling of cows
and replacements and possibly by earlier weaning.

Almost yearly changes in stocking are necessary because a reserve of
forage cannot be built up on the ground in good years. Dry herbage of
annual plants is ruined by leaching during the winter. It appears feasible,
however, to keep a reserve of hay above the usual yearly needs (12). This
hay reserve, often obtainable at a lower cost before the start of a drought,
ean be stored under cover with little deterioration. Besides filling part
of the needs for roughage in years of low grass production, the hay may
be needed in other emergencies, as when growth of green forage is greatly
delayed in late winter or when grass fires cause sudden loss of dry vegeta-
tion.

Experience with both a breeding herd and yearlings at the experimental
range indicates that the foregoing method of operation is feasible and
will allow the necessary adjustments in livestock numbers in all except
the occasional years of extremely low herbage production.

Fluctuations in the composition of the herbage crop should also be
considered in stocking foothill ranges. The amount of grass in the plant
mixture is of special importance on ranges grazed from summer until

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 29

: Y
Z, Z Y
Oo p20 go
< AY AA YZAOagnGy
AAA
- |AYGGGAGGOGGAGGe
= |~OUAGGOGGAGAGZ
: wABAABZAAZCAAGAGae
MeN
eA AAAAAAANNNAA
\GOGGLAAALAAA

Ficure 14.—Kstimated annual production of air-dry herbage from grasses and
grasslike plants per grazable acre, San Joaquin Experimental Range, 1936-48.

winter. Grasses are the chief source of dry forage at that time of year.
During the 13 years, 1936-48, the production by grasses and grasslike
plants each year in pastures /, 2, and 3 (fig. 14) was estimated from
clipped samples, density records, and other field observations. These
records show that the yield of grasses and grasslike plants varied less
than did total herbage production (fig. 13) up to and including 1946.
Livestock adjustments based on variations in total herbage were sufficient
in these first 11 years.

After 1946, however, grass yields fluctuated more than total yields,
presenting a more critical stocking problem. The proportion of grasses in
the herbage was progressively lowered during the dry years after 1946.
Filaree dominated the plant cover in 1947 and 1948; consequently, grass
yields were lowered much more than total yields. By 1948 grass yields
were only about 42 percent of the 13-year average. Under these condi-
tions a greater amount of supplements was needed in the summer to
balance the lower quality of the dry roughage, and hay was needed during
the fall and winter, even though fewer livestock were grazed.

Nevertheless, most fluctuations in individual species have relatively
minor effects on range stocking. Observations on several important
forage species bear out this conclusion. In years of high clover yields,
for example, the herbage was considered of better forage value than in
other years. However, in ‘‘good clover years” there is no shortage of
forage and the problem may be to increase stocking. Again, because soft
chess matures late, its growth and seed production depend on adequate
late spring rains. Value of the dry herbage was considered better in the

30 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

years when there was a vigorous growth of soft chess with large seed
heads; but when. yield of soft chess was low, the number of animals that
could be carried on dry forage was also limited by total grass production.
A third example is afforded by broadleaf filaree. This plant, which is
more dependable as a source of green forage early in the spring than any
of the other species, usually produced about 25 percent or more of the
total herbage at plant maturity. But its yield was low in 1938 because
of late fall rains in 1937, followed by prolonged cold rains; it composed
only 9 percent of the total herbage production. However, the shortage
of filaree in late spring was more than offset by high production of other
species.

Thus it is evident that nutritive value of the forage is affected each
year by fluctuations in clovers, soft chess, and other valuable forage
species, but grazing capacity is affected mainly by variations in total
herbage production and total grass production. Both the kinds of land
on the range and the annual precipitation need to be considered in ad-
justing ranch stocking to meet these variations.

SELECTING THE MOST EFFICIENT DEGREE OF
GRAZING

To insure both high livestock production and good forage cover, the
ranch operator needs to select the degree of grazing that will give the
most efficient utilization of the forage over a period of years. Results
of the grazing-intensity experiment will aid in this selection by showing
how different degrees of grazing affect both cattle and herbage production.

The experiment was planned to determine how closely annual plants
can be grazed without adversely affecting either forage growth or cattle
production. The stocking dates for each year were:

Year: Entry date Removal date
bal a) ye ea ae Zo PO le ck Deh piel a pl: Bel aR January 10 August 4
sD aig OE ie Me a deve Serer TR ue oe, Mee sil January 2 August 10
[Ls Seay aoe er ag pans Portia SAC ys fas RO ee aco February 25 September 2
D5 Sees Oe iy oe A ee ee January 25 August 1
140 i ea Oe Ce ee ee a een ae eee February 8 August 4
F872 MOIS Lecewan enya oon Ger ene be Eh Seg les February 1 August 13
2. 2 a a ty as en eae see es er ae LAS ON January 20 August 6
CY Fe ry ene gies tee Pensa ere en se et a February 12 July 30
TON A A CESS ey et ee eee Se ae March 7 July 20
1 OA yp See ee we Pie) pie Laie 8 eee les pee January 16 August 8
[CS YE (aha es sa Ae em RAG iar Gakes PN he et Sa Wh 7 January 9 July 14
TON ME Se A ad eh pe February 5 July 1

AVeTaAgetsiT' RRO yt sh mee See ee een January 29 August 1

The grazing season in the experimental pastures covered the period of
best forage on foothill range and included only a limited period of forage
shortage in the most closely grazed pastures. Grazing started in the
winter when the plants were still growing slowly and continued through
the spring when the plants were growing rapidly. Since cattle could
not keep up with the rapid spring growth, there was adequate seed pro-
duction of the important forage species — at least on most sites. The
vegetation was not grazed to the final degree of utilization until after
the plants were mature and dry. Effects on vegetation of the different
degrees of grazing obtained should be representative of those which
would occur under the usual seasons of grazing.

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 31

TABLE 6.—Degrees of utilization in six grazing-intensity pastures, San
Joaquin Hxperimental Range, 1937-47

Year Pasture Pasture Pasture Pasture Pasture Pasture
1 9) 4 6
1937 | Very close_| Close_____ Close___--| Moderate _| Moderate | Light to
to light. moderate.
1938 | Close_____- Moderate | Moderate | Moderate | Light____- Light.
to close. to close. to light.
1939 | Very close_| Close to___|._._do____- ne Ou UN REA. © ustenien Do.
moderate.
1940 | Close_____ Moderate | Moderate _| Light to Light to Do.
to close. moderate. | moderate.
OA ea doz a2es nb Ate Vo aenaciatl Bed Oe 0 ae Ow sural Inghte caer Do
OA ZS ee Adobe t=. Saori Dae doun a! agen o (0 un een WG Ogee see Light to
| : moderate.
OA i= s2doEs= = s\-Moderate|| Moderate. |... do... - ee ek OU autre Light.
to light.
1944 | Very close_| Close to Moderate _| Moderate _| Moderate | Light to
moderate. to light. moderate.
1945 | Close. .___| Moderate | Moderate | Light _____ Ihnghtes sa8 Light.
to close. to light.
ROA Ge es SON ain Moderate _|-._-.do____: Light to 2s COU ae. Do.
moderate.

1947 | Very close_| Close to Moderate _| Moderate | Light to Light to

moderate. to light. moderate. | moderate.
Aver-
ages le Closes ues Moderate | Moderate _| Light to___| Light ____- Light.

to close. moderate.

The planned procedure was to remove the cattle from the pastures at
variable dates from year to year, depending on herbage yields, in order
to obtain somewhat the same degree of grazing each year in any given
pasture. It was found impractical to follow this procedure in all years.
In years of low herbage production the pastures were grazed closer than
average (table 6), especially in 1937 and 1939 when the cattle were kept
in the pastures until August. During the last 5 years (1943-47) the cattle
were removed earlier than in previous years; even so, grazing was some-
what closer than average in 1944 and 1947. The experience in stocking
emphasized the need for flexibility in ranch stocking if utilization of the
fluctuating herbage crop is to be kept within narrow limits.

The utilization of the pastures at the end of the approximate 6-month
season for an ll-year average included five different degrees of grazing.
There were three basic degrees; close, moderate, and light. When the
average utilization of a pasture in any year did not fit one of these three,
intermediate ratings were used; for example, “‘moderate to close’’ in-

o2 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

dicated a degree that was nearer to moderate than to close, while ‘‘close
to moderate”’ indicated utilization was nearer to close.

EFFECTS OF DIFFERENT DEGREES OF GRAZING ON CATTLE
PRODUCTION

A brief consideration of how different degrees of grazing affect cattle
production will aid in interpreting the effects on sustained forage pro-
duction. Members of the Division of Animal Husbandry, University of
California, who were in charge of the cattle phases of the experiment,
have reported the findings for 1937-48 (4). Their results, summarized
here, show that heavy stocking, even for only part of the year, on annual-
plant ranges means lowered efficiency of production from a breeding-cow
herd.

Average gains and weaning weights of calves were low in closely grazed
pasture 3, particularly for calves from the ‘“‘B” herd which received no
supplements, but also for calves from the ‘‘A”’ herd which received supple-
ments while out of the grazing-intensity pastures (table 7). Variations
in gains and weaning weights of calves in the other five pastures were
not related to degree of grazing; the variations were apparently caused
by other factors. The lower calf gains in pasture 3 emphasize the im-
portance of having an adequate forage supply for cows during the nursing
period.

TABLE 7.—Average gains and weaning weights of calves from supplemented
and unsupplemented herds grazed in six pastures, 1937-43 !

Calves from supple- | Calves from unsupple-
Pasture mented ‘“‘A”’ herd mented ‘“‘B” herd
number Degree of grazing Ste mA

Gainsin | Weaning | Gains in | Weaning
pasture weight pasture weight

Pounds Pounds Pounds Pounds

Syl Closes Sera ena Mae 265 459 241 378
1 | Moderate to close_______- 292 504 291 447
Oy; Moderates eee ee yea 281 459 286 432
4 | Light to moderate______-__ 284 490 285 435
Gili WetonG es dee era a Reet 268 462 299 453
if | ape so CG an Ana ea fhe ete kt 292 493 300 447

1 Source: Hart, Wagnon, and Guilbert (4).

The cows in closely grazed pasture 3, from the unsupplemented “B”’
herd, always gained less than did the cows from this herd in the other
five pastures and were always thinner at the time they left the pasture
(table 8). Cows from the supplemented herd also gained less in the
closely grazed pasture than did their mates in the other pastures. For
the unsupplemented cows, gains and final weights were also lower in

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS

3d

TABLE 8.—Average initial weights, final weights, and gains of cows from
both the supplemented and unsupplemented herds grazed in six pastures,

1937-43 }
Pasture
number Degree of grazing

Initial
weight

Cows from supple-
mented “A” herd

Final

weight | Gain

Spi ClOseseiim 838 939 101

1 | Moderate to close_ _. __ 857 | 1,002 145

oneNVroderate:s: Bolen 872 | 1,016 144

4 | Light to moderate____- 869 | 1,023 154

Gialdeie mien iat ee 871 | 1,032 161

Dele ClOl nares, sia Ne CD 819 | 1,023 204
1Source: Hart, Wagnon, and Guilbert (4).

Cows from unsupple-
mented “B”’ herd

Initial | Final
weight | weight

Pounds |Pounds \Pounds |Pounds |Pounds |Pounds

725 | 868 143
GOD My 875 176
754 | 978 224
ree | Gp 194
766 | 1,026 260
7 O37 220

TaBLE 9.—Percentage pregnancies and percentage calf crop of cows from
both the supplemented and unsupplemented herds grazed in six pastures,

1937-43 }
Cows from supple- | Cows from unsupple-
Pasture mented “‘A”’ herd mented “B”’ herd
number Degree of grazing roa aN ces ta
Preg- | Preg-
nancies | Calf crop | nancies | Calf crop
Percent Percent Percent Percent
Sr ClOSe meee wa sae ek UN 91.4 82.8 65.0 60.0
1 | Moderate to close______-- 89.2 78.4 70.6 61.8
Dele Moderate ies eee 86.5 86.5 83.3 77.8
4 | Light to moderate_____._- 97.4 89.5 85.7 PUPAE
Opleibig inter be 88.2 79.4 80.0 (2.5
Dil cpanel vee ded 95.0 82.5 85.3 73.5

1 Source: Hart, Wagnon, and Guilbert (4).

pasture 7 under moderate-to-close grazing than in more lightly grazed
pastures. Variations in cow gains among the other four pastures, grazed
from moderate to light, were not related to degree of grazing. Part of
the variation was caused by differences between pastures in the amount
of steep south slope, where the forage grew faster in late winter and dried
earlier in the spring.

34 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

This experiment produced only limited information concerning the
effects of degree of grazing on the calf crop. Percentage pregnancies
and calf crops for supplemented cows (table 9) did not differ significantly
between experimental pastures. Supplements received during the fall
and winter apparently offset the effects of differences in degrees of grazing
during the remainder of the year. Yet stocking to a degree closer than
moderate during late winter, spring, and early summer did affect repro-
duction from unsupplemented cows. As stated by the animal husband-
men (4), there is a good indication ‘‘that the lower percentage of preg-
nancies and calf crop of group B (unsupplemented) cows in pastures 3
(close) and 7 (moderate to close) is related to the lower gains and
weights of these cows.”’

The experiment shows, too, that net gain per acre is not a good ex-
pression of efficiency of operation for a breeding herd. The average yearly
gain of all cattle per grazable acre was greatest under close grazing and
decreased with increase in the amount of grazable land available per
animal unit: from 43.1 pounds in pasture 3 to 23.4 pounds in pasture 6,
with pasture 2 as an exception at 32.5 pounds per grazable acre. But, as
stated by the animal husbandmen (4), “‘while pasture 3 shows the highest
return in pounds of gain per grazable acre, it should not be concluded
that this is the most profitable use. The cattle were always thinner, the
gains contained less energy because of lack of fat, the calves weighed
less at weaning time, had less bloom, and were worth less per pound.
Efficiency of production for those not receiving supplemental feed was
further reduced because of lower calf crops. . . . Thus there are limita-
tions of greatest return in pounds of beef per acre as a criterion of most
profitable rate of stocking. Rather, the criteria should be the maximum
returns per acre compatible with maximum gains of the cattle, high
percentage calf crops and optimum weaning weights. . . . That animals
do not thrive where they do not get enough to eat is not news to most
livestock men. Some cling to large numbers poorly fed and thus use
too high a proportion of feed resources for maintenance. This leaves too
little for production and sacrifices efficiency through lower weights, calf
crops, value per pound, and increased death loss.”

EFFECTS OF DIFFERENT DEGREES OF GRAZING ON HERBAGE
PRODUCTION

Grazing to a moderate degree which gave efficient cattle production
also maintained satisfactory herbage production. On the other hand,
close grazing reduced range forage production as well as efficiency of
cattle production. The effects of degree of grazing were apparent in the
winter growth of forage and in yield of mature herbage.

EFFECTS ON PLANT GROWTH DURING WINTER

Close grazing consistently reduced winter plant growth. Even though
the closely grazed range appeared greener, the new plants were shorter
than on areas grazed moderately or lightly. This difference was found
in measurements made along fence lines and on permanent sample plots
in the grazing-intensity pastures, and it is well illustrated by intensive
measurements made in January 1943 on 100 square-foot quadrats in

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS oy)

DEGREE OF GRAZING

CLOSE MODERATE LIGHT TO
TO CLOSE MODERATE
3 AVG. HEIGHT
WB avc.yieLo ae
| 4
Iso =
S
98
Q
>»
aT
Ss
i. Q
aS t
= :
nN
—_—
K
= 100 4,
: y :
|
= Wf i
| 4, &
| lw
Y :
Q
y :
Y, 50 >
: 7 4 ;

PASTURE 3 PASTURE | + ~—~ PASTURE 2

FicgurE 15.—Average height and yield of new vegetation in January 1943 in three
range pastures in relation to degree of grazing of each pasture in the preceding year.

each of pastures /, 2, and 3. These three pastures were chosen for in-
tensive measurements because they were most comparable in kinds of
land and included both of the two most closely grazed range pastures,
in which degree of grazing was likely to be critical, and one of the lightly
grazed pastures.

In the two pastures that had been most closely grazed, the vegetation
was hardly tall enough to be grazed on most of the area. The average
height of -all species in each of these two pastures was between 14 and
34 inch (fig. 15), with grasses averaging between 114 and 2 inches. But
in pasture 2, grazed light to moderate in the preceding year, the new
plants were tall enough for some grazing over most of the pasture and
were readily grazable on about half of the acreage. In this pasture the
average height of all species was more than 1 inch, with grasses averaging
about 21% inches.

Because of greater height and increased leafiness, the average yield of
plants clipped at 14-inch stubble height during January 1943 in pasture 2

36 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

was three times as great as in pasture 3, and more than 50 percent greater
than in pasture 7. Production was uniformly low on all sites in the two
more closely grazed pastures. Grasses produced about 75 to 90 percent
of the available new growth in each of the pastures.

The differences between pastures were only about 50 pounds of air-dry
forage per acre, but even such small differences in the production of new
forage are important in this period when cattle have difficulty in obtaining
sufficient green forage for their minimum requirements. Furthermore,
at this stage the forage is a ‘‘watery concentrate;’ air-dry, it is comparable
to many commercial concentrate feeds. Fifty pounds of air-dry forage
per acre represent a considerable bulk of green material.

Close grazing also delayed the date when new forage was adequate, thus
lengthening the time that expensive supplemental feeding was necessary.
Each year when the cattle entered the six grazing-intensity pastures, the
new forage was considered adequate in each of the four pastures grazed
from moderate to light the previous year. But it was not considered
adequate in pasture 3, grazed close, and pasture J, grazed moderate to
close in preceding years. Observations during 3 years on some 200 small
temporary enclosures that were relocated each year and protected from
cattle grazing until May, indicated that the forage in the closely grazed
pasture would not have been ready until shortly before the start of the
spring growth period. Since spring growth started about the first week
in March on the average, close grazing caused an average delay of about
3 weeks in the date when the forage was ready to graze without supple-
ments. The delay in the pasture grazed moderate to close was about
half that in the closely grazed pasture.

This delay in growth of late-winter forage was reflected in weight gains
of the cows for the first few weeks they were in the pastures. First weighed
when they moved into experimental pastures, the cows were weighed
again when the forage in all pastures was abundant enough to provide a
fill. By that date, averaging March 21 during 9 years, cattle had been
in the pastures an average of 51 days. That period included the end of
slow winter forage growth and the start of accelerated spring growth.
For the entire 51-day period, which included some time when forage was
adequate in all six pastures, average gains® of cows with calves at side
were:

Supplemented Unsupplemented

Pasture (degree of grazing) : cows (pounds) cows (pounds)
(© G-series ge Re ate Seal aen aes ow SER eRe eet a SS Zee 46.5
i= WModerate toselose: 2 Bnet. area ewes Aue eG eye ee eee 26.8 65.6
ya MG er ate wea eo es CAL RS Bick ae pie cop am nee ie er ad eae 67.1 1 Bo Sip’
4y-ight to moderate): 5st ae Re ey ee See 63.9 106.0
(CNet "4 0% Fal eae Pin RE Tne OE SRY Wrath Cots SE GE cys Seth” 51.0 100.6
pate Pp a i 0 Meee Aa ae py, ee eens a eels 7 A AE © 68.1 110.6

Cows which received supplemental feeds before entering the grazing-
intensity pastures as well as those that had not been supplemented gained
much less in the two pastures that had been most closely grazed than
did cows of the same group in more lightly grazed pastures.

Better winter growth of green forage under light or moderate grazing
is undoubtedly related to the amount of dry vegetation left ungrazed.
The dry vegetation left on the range at the beginning of the fall-winter

8 From unpublished data in files of Division of Animal Husbandry, University
of California, at the San Joaquin Experimental Range.

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS Oo”

period promotes the growth of green forage in two ways. First, the
upright herbage protects the new plants from drying winds and sun.
Second, the decomposing herbaceous material lying flat on the soil
surface, and partially intermixed with the mineral soil, conserves moisture
and aids establishment and early growth of each year’s seedlings. In the
grazing-intensity pastures, herbage production during the winter was
observed to be consistently greatest on range land with an adequate
layer of decomposing litter. Exceptions occurred on small spots recently
cultivated by gophers or where moisture accumulated at the base of
boulders; but on the whole, plant growth was sparse where there was a
shortage of litter on the soil surface.

The layer of old litter was not maintained over most of the soil surface
in the two pastures that had been grazed closer than moderate. In
pasture 3 (closely grazed), of 99 square-foot quadrats examined in
January 1943, about 75 percent had almost no litter; about 15 percent
had a thin, spotty cover; and less than 10 percent had a fairly continuous
layer of decomposing herbaceous material. In pasture / (grazed moderate

OLD LITTER ON SOIL SURFACE
300 NONE FAIR ADEQUATE

200

NEW HERBAGE PER ACRE (AIR-DRY POUNDS)
NAAR
QUARRY

g

/

yiY

41 GGlgg

Z| GUigg

100 y, Y Y Y

ZA Ung A\™

—4Z\GG AG

ZUG 4%

ZeoOlA GY a7,

AYA GY 4G

ZOGi4 Gg Gig Z
: Z Z Z C A GHT® hit ne fr

UTILIZATION OF PRECEDING SEASON
®°SMALL SAMPLES

Figure 16.—Yield of new green vegetation in air-dry weight pounds per acre, clipped
at 14-inch stubble height, as influenced by the layer of old litter lying flat on the
soil surface and by the degree of utilization of the preceding season.

38 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

to close), half of the quadrats had practically no decaying vegetation on
the soil surface; one-fourth had a thin, spotty layer; and the remaining
fourth had a continuous layer about 44 to 14 inch deep. The nearly
bare areas were found fairly generally over this pasture on most of the
better sites. Soil-surface conditions were better than in the closely
grazed pasture but still not satisfactory.

In contrast, there was some old herbaceous litter flat on the soil surface
in all parts of the more lightly used pastures. For example, nearly half
of the 97 small quadrats examined in pasture 2 (grazed lightly) had a
continuous layer of decomposing herbaceous material between 14 and 4
inch deep, and nearly one-fourth had a thin, spotty layer. The remain-
ing quadrats had almost no old litter, but these quadrats were of scattered
occurrence, falling almost entirely on poor, sandy soils, on recent rodent
workings, or on closely grazed swale bottoms or livestock trails. Such
small local areas of exposed soil can be found on any range, even though
it 1s in satisfactory condition.

Observations within the other lightly or moderately grazed pastures
on the experimental range indicated that the soil-surface conditions were
similar to those in pasture 2 although more soil without any litter could
be found in parts of the moderately grazed pasture. The vigor of plant
growth and the general lack of exposed soil during the winter showed
that these pastures were in satisfactory condition under the present cover
of annual plants.

The importance of unused vegetation and the layer of litter it produces
was shown by the yield of herbage in January 1943 from the 295 sample
quadrats (fig. 16). A rather continuous layer of the old litter, 4 to %
inch deep, was designated as adequate. Where the layer of litter was
adequate, on quadrats that had been lightly grazed the preceding season,
the yield of new green herbage was nearly 300 pounds per acre, air-dry
weight, and on moderately grazed quadrats the yield was nearly 200
pounds. Such yields over a range area would provide sufficient green
forage to maintain cattle. With an adequate layer of litter, growth of
green forage was nearly sufficient even on the few quadrats that had been
closely grazed.

Where the layer of old litter on the soil surface was thin and spotty,
designated as fair, growth of green forage was reduced on quadrats
that had been grazed moderately or closely during the preceding season.
On the few such quadrats that had been lightly grazed, forage growth was
satisfactory.

Where there was virtually no layer of old litter, growth of new forage
was very greatly reduced, particularly on quadrats that had been grazed
moderately or closely during the preceding season. Even on the lightly
grazed quadrats, yields averaged less than 150 pounds per acre.

These results show that moderate and light grazing promote winter
growth of herbage, but full winter production will be obtained only when
an adequate layer of litter has been built up by conservative use in pre-
ceding years.

EFFECTS ON MATURE SPRING HERBAGE

The effects of degree of grazing on plant vigor that were readily ob-
served during the winter were not so easily seen later in the season.
Differences in grazing during the current season partially obscured the

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS a9

TABLE 10.—Average yield at maturity of herbage, by plant group and
species, on slopes and swales for the period 1943-45, in three pastures
grazed to different degrees from 1936 to 1945

Yield per grazable acre Yield per grazable acre
on slopes under— on swales under—
Plant group
and species
Close | Moderate) Light Close | Moderate] Light
grazing | toclose | grazing | grazing | to close | grazing
(pasture | grazing | (pasture | (pasture | grazing | (pasture
3 (pasture 2)) 3) (pasture PA)
1) 1)
Pounds | Pounds | Pounds | Pounds | Pounds | Pounds
Grasses:
Soft chess______ 391 473 614 90 ist 7s 143
Foxtail fescue __ 165 234 218 1,053 887 657
Ripgut brome _- i 13 CYGWIN gL
Mediterranean
par leweanir ae eer hee 2 211 1,172 1,949
Waldeoatens 2” 6 9 Pe ree aie AO haa Me ee ra
Othersle2 eos 33 54 48 94 55 96
Potaletat 8 ei 602 783 984 1,448 2-231 2,845
Grasslike plants:
TIGRE LT eS ns SEE ts pC Dd sade ie Pe Ae 42 27
Perennial
MUSES Merwe wads Elo) as 1 252 112 415
ZAIN ay Le 2 rt EE aes a a 1 325 154 442
Broadleaved plants:
Hilarees 20a 316 601 583 222 321 246
Cloverss 225.2) 39 59 67 453 565 488
Other legumes_ _ 83 127 93 44 30 36
Smooth cats-ear SH 8 3 16 6 i
Windmill pink__ 36 12 ga A ra ele a GA Ne ener Ha
AO GO gay ane ieee aN aor ek A De 109 12 7
Others GON vec 139 145 141 214 22, 328
otal anes 644 952 901 1,058 1,146 1,106
All species_ __ 1,246 L735 1,886 2,831 3,00 1 4,393

effects of past grazing use. The effects on yield and composition of the
mature vegetation, however, were apparent from measurements made
on the sample quadrats protected from current grazing (fig. 3, p. 6).

Mature herbage yield was lowest under close grazing (table 10), but
differences in both productivity of the sites and degree of grazing con-
tributed to the differences in yield between pastures. ‘To illustrate, the
productivity of swale soil was uniformly high in all pastures, so the low
yield of swales in pasture 3, in contrast to the swale yields in pastures
7 and 2, was mainly the result of long-continued heavier grazing. ‘The
herbage yield there was only 64 percent of the yield under light grazing,
which was most favorable to plant growth. On the other hand, the
productivity of slope soils varied considerably, and as pasture 3 had more
of the poorer sites than pasture 2 (fig. 12, p. 24), only a part of the reduc-
tion in yield on slopes was due to differences in degree of grazing.

40 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE .

That close grazing did reduce the yield from slopes, however, was
quite evident. Several comparisons were made of small areas of similar
sites across the fence line between pastures 2 and 3 during the years
1943-45; they indicated that the yield on slopes was reduced under close
grazing and that the greatest reduction was on the most productive
sites. Then, too, in 1944 a fenced plot about 66 feet square was placed
astraddle of the fence line between pastures 2 and 3. It was situated on
a highly productive gentle-slope soil, in the only area of appreciable size
where comparisons of similar sites could be made directly across the fence
line. Yield was measured on three sample transects in each pasture.
The average in pasture 2 was 3,624 pounds per acre; in pasture 3 it was
2,254 pounds — a reduction of 38 percent after 8 years of continued close
grazing.

When the experiment ended in 1948, yields were measured for these
two pastures as a whole. In pounds per grazable acre, herbage yields
were 1,379 for slopes and 2,225 for swales in pasture 2, and 837 for slopes
and 1,224 for swales in pasture 3. On slope sites the yield in the closely
grazed pasture was 61 percent of that in the lightly grazed pasture, about
the same as in 19438 and 1944. The yield of swale sites, however, was only
55 percent of that in the lightly grazed pasture, slightly lower than in
the other years when yields were measured.

Moderate-to-close grazing (pasture 1) had a measurable effect on
total herbage yield only in the swales. The average yield on swale soil
in pasture 7 was 80 percent of that in the lightly grazed pasture 2 (table
10). As was the case with pasture 3, the reduction was caused mainly
by heavier grazing. Unlike the case with slopes of pasture 3, however,
the lower yield on slope soil occurred mainly because pasture J had a
lower proportion of the more productive site classes. Comparisons of
yield on similar sites across the fence line between pastures 7 and 2 did
not reveal any consistent differences that could be attributed to grazing
treatment.

Because the effects of different degrees of grazing on total herbage
production were different on each site, the combination of site classes
within the pasture had to be considered in judging the extent that pro-
duction was reduced by elose grazing. To do this a “potential yield”
for each of three pastures for 1943-45 was computed. First, the acreage
of each site class in the pasture was multiplied by the estimated yield
per surface acre of this site class (from table 4) to obtain its expected
yield. Then the total potential yield for the pasture was obtained by
adding the expected yield from each site class. This computed potential
yield for pastures /, 2, and 3, and the measured total yield from sample
quadrats in each pasture were:

Yield
Potential Measured
Pasture and degree of grazing: (pounds) (pounds)
Basbrine v2) (lig init) sesame are Eee ng ee so a re 394,276 395,293
Pasture sl h(moderate toclose) 522 one eee noma uare apenas 262,755 262,836
Pasture eo s(Close iste at od ois V5 Saeed. ee JR i pe ont ay De ee 187,815 142,264

For all sites combined, the closely grazed pasture 3 was producing only
about three-fourths of its potential herbage production. Each of the
other two pastures was yielding near its calculated potential. Although
this method of analysis did not show all the differences between pastures,

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 4]

it did show that only in the closely grazed pasture was mature herbage
production greatly influenced by degree of grazing.

In these studies high herbage yields were obtained on all sites under
light grazing. But this degree of grazing left considerable unused herbage
on the ground that might well be grazed by livestock. Grazing to a
moderate degree will give efficient livestock production, and it will leave
sufficient unused vegetation to maintain satisfactory soil-surface condi-
tion and sustained herbage production. It is clearly more efficient use
of the available forage.

Although yields of each major plant species on slopes, such as soft
chess, foxtail fescue, filaree, and clover, were less in the closely grazed
pasture, the percentage of each major species in the herbaceous cover on
slopes was not greatly different in pastures that had been grazed at
different degrees (table 10). For example, the yield of soft chess in
closely grazed pasture 3 was 391 pounds per acre as an average for 1943-45,
and the yield in lightly grazed pasture 2 was 614 pounds, the percent of
total yield being 31 and 33 respectively in pastures 3 and 2. In pasture /,
grazed at an intermediate degree, soft chess composed 27 percent. Fox-
tail fescue produced about 12 to 13 percent of the yield in each pasture.
The differences in proportion of major species on slopes that did occur
between pastures — for example, the greater percentage of filaree in
pasture / — were present at the start of the experiment. Density estimates
showed these differences occurred in 1936 and remained until 1943 when
yield measurements were started. Measurements in 1948 showed that
at the end of the experiment each of the major species composed about
the same proportion of the herbage on slope soils in pasture 3 as in pasture

There were, however, noticeable differences in the abundance of species
ordinarily dominant on swale soils. The closely grazed pasture had a
much lower yield and a lower percentage of Mediterranean barley and a
greater amount of foxtail fescue than the more lightly grazed pastures
(table 10). This is not a desirable change because Mediterranean barley
in the swales starts growing earlier and dries later than foxtail fescue.
In the pasture grazed moderate to close, the amount of Mediterranean
barley in the swales was considered adequate even though the yield and
percentage were less than in the lightly grazed pasture.

Both yields and proportions of some minor species in the herbage were
changed by degree of grazing on both slopes and swales. ‘Two tall-growing
grasses (slender oat and ripgut brome) increased slightly but gradually
from 1936 to 1943 in lightly grazed pasture 2. During the period 1943-45,
the combined average yield of these species in that pasture was 102 pounds
per acre of slope soil. Present in this amount, the two grasses are desirable
additions to the winter forage.

Minor forbs of low forage value (particularly smooth cats-ear and
- windmill pink on slopes and pogogyne in swales) increased under close
grazing (table 10). Smooth cats-ear increased in pasture 3 after 1941;
by 1944 it made up 12 percent of the total plant density in that pasture.
Because of the wide leaved, rosette form of smooth cats-ear (similar to
the form of dandelion), its greater abundance under close grazing was
very apparent even though it produced only 31 pounds per acre in pasture
3 as an average for 1943-45. The species was not conspicuous in the
plant cover on the other pastures.

42 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

This study and widespread observations show that when grazing use
is too ight on California foothill range, tall-growing annual grasses crowd
out filaree, clover, and other valuable low-growing plants. This change
to a less desirable mixture 1s most rapid — and most complete — on fertile
soils and with fairly high rainfall. On the experimental range virtual
nonuse was required to bring about this undesirable increase in tall
grasses; the change has been observed under light use on more productive
soils. The conclusion is that even though complete protection from
grazing for 1 or 2 years may be Justified to restore a litter cover on a de-
pleted range, continued very light grazing will not maintain a satisfactory
forage plant mixture on annual-plant ranges.

As to herbage composition, then, a satisfactory mixture of annual
plants was maintained under degrees of grazing ranging from a little
closer than moderate to light. Under close grazing there was some in-
crease in weedy species. Moderate grazing has maintained a satisfactory
forage mixture and yield under all conditions that have been observed on
foothill range.

RECOGNIZING SATISFACTORY RANGE UTILIZATION

The lack of pronounced changes in the composition of the herbaceous
cover during the grazing-intensity studies emphasized that relying on
the percentage of any annual-plant species as an indicator of grazing use
has definite limitations on these granitic soils. Also, the plant mixture
under each degree of grazing changed in species composition from year
to year, as is typical on foothill ranges. The only conspicuous change in
the mixture to indicate the effects of close grazing was the appearance
of smooth cats-ear in pasture 3. This species has also been observed
erowing on other relatively bare soils, including soils derived from sedi-
mentary and igneous rocks, under a wide range of precipitation. Under
these variable conditions, however, the lack of old litter on the soil surface
was ample indication of close grazing without reference to composition
of the plant mixture.

In fact, without reference to the condition of the soil, appraisal of
annual-plant forage production on the range is both difficult and apt to
be misleading. The level of herbage production cannot be judged merely
by the general appearance of the plant cover in the spring. Yields, for
example, were different between range pastures having about the same
percentage of each dominant species in the cover. Similarly, differences
in yields at plant maturity cannot be evaluated readily by general
observations because the vegetation is grazed at different intensities
during its growing season. The only exception to this principle that
could be seen in the experiment was the noticeably reduced vigor of the
forage plants in the swales of the most closely grazed pasture.

The studies at the San Joaquin Experimental Range have provided
two useful guides to satisfactory utilization of annual-plant range. The
first is a simple means for judging adequacy of old litter on the soil
surface. The second is a practical method for rating the degree to which
herbage of the current year has been utilized.

JUDGING ADEQUACY OF OLD LITTER

Full production of forage depends upon an adequate layer of old de-
composing litter lying flat on the soil surface. The extent and thickness

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 43

of the old litter, or condition of the soil surface, is best observed during
the winter, when the beneficial effects of a protective soil covering are
most apparent (fig. 17). The layer of litter is not so readily observable

F—460561
Fiaure 17.—Appearance of foothill range in January—the time of year when condition
of the soil surface is best rated.

during the spring because it is more completely masked from view by
vegetation. Then, too, differences in grazing during the preceding
months affect plant height in the spring so as to obscure the effects of
soil-surface condition on plant vigor. During the winter months, how-
ever, both the litter layer and the vigor of new plant growth can be con-
sidered as indicators of the productive condition of California foothill
ranges.

A foothill range with unsatisfactory soil-surface condition has very
little decomposing herbaceous material on the soil surface, and the sparse
and stunted plant growth provides only a thin vegetative cover. Mineral
soil is readily apparent during the winter months over all of the range in
unsatisfactory condition. The hard, exposed soil surface inhibits the
establishment and growth of annual-plant seedlings.

There are other indicators of unsatisfactory conditions. ‘The mineral
soil is commonly covered with a short growth of moss, lichen, or plants
of similar appearance. The thin, black humic layer that ordinarily
covers the mineral soil may disappear after the overlying herbaceous
layer is lost. A miniature erosion pavement is often formed as a result of
loss of organic matter and possibly of some fine mineral soil. After heavy
rains, local movement of soil particles is evident in the tiny terraces that
are formed even on gently rolling slopes, and particularly on south slopes.

Even so, accelerated erosion may not be readily apparent on foothill
ranges with unsatisfactory soil-surface condition. Close examination may
reveal slow insidious movement of the soil, as in closely grazed pasture 3,

44 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

which had more small spots with broken soil surfaces, and more unstable
soil in drainage channels and slopes than the more lightly grazed pastures.
Yet in general this pasture showed no conspicuous evidences of accelerated
erosion.

A supplementary study on nine 1/40-acre plots found no significant
surface runoff of precipitation or erosion from either close grazing, moder-
ate grazing, or nonuse (10) although unsatisfactory soil-surface conditions
with local movement of soil particles developed on the closely grazed
plots. The infiltration capacity of the soil was significantly reduced as
compared to the moderately grazed plots, and very significantly reduced
as compared to the ungrazed plots. Still, the infiltration capacity of the
soil on all plots remained high enough to absorb the rainfall that occurred
during the study. This finding helps explain the relative scarcity of
conspicuous soil erosion on rolling foothill lands closely similar to the
San Joaquin Experimental Range.

The usual patterns of precipitation and plant growth in this locality
also helps the explanation. Characteristically, the first fall rains are
fairly gentle. Germinating and growing quickly, dense stands of annual
plants, particularly the flat rosettes of filaree, form a protective cover
over much of the soil surface. Winter rains are seldom torrential. Con-
sequently, under the usual rainfall pattern the porous soils of granitic
origin absorb most of the precipitation as it falls. Where soils are less
permeable or the annual-plant cover is scant, however, the hazards of
runoff and erosion are greater.

A range unit with satisfactory soil-surface condition will have a layer
of old litter on most sites in all parts of the area. In general, the moist
ground in winter will feel soft and springy under foot. The thin layer
of decomposing herbaceous material and the relatively thick, even, and
vigorous growth of green plants will leave almost no bare soil apparent
to observers walking or riding over the range during the winter. These
conditions will be found in all but the rare winters when weather condi-
tions are so severe that plant growth is very sparse regardless of past
utilization.

As explained previously, moderate grazing will maintain a satisfactory
layer of litter over most of a range unit. Under this degree of utilization
the litter may be thin on limited areas of livestock concentration, such as
wet swale bottoms, but the soil surface on these sites will be stable,
though somewhat compacted. On ranges with an unsatisfactory layer
of old litter, a lighter degree of grazing will often be needed. How long
this lighter grazing must be continued to build up the hitter on ranges
that have been closely grazed for a number of years is not known. It
has been observed, however, that where the reduction in litter is limited,
satisfactory conditions may be restored by light grazing during a single
year of heavy forage growth.

RATING USE OF EACH YEAR’S HERBAGE

The degree of grazing of the current year is rated from the amount of
unused herbage of that year. On foothill ranges utilization is best rated
at the time of the first fall rains to determine how much plant material
is left to provide dry roughage and promote new green growth during
the fall and winter.

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 45

The basic set of utilization standards (9, 5) consists of three photographs
illustrating light, moderate, and close utilization, with descriptions of
the kind of grazing typical of each degree of utilization. A numerical
index scale (6) was also developed to simplify recording of intermediate
degrees, but for practical ranch operation the three photographs are
sufficient.

By comparing the appearance of the grazed range with the three
photographs, the degree of grazing obtained that year can be readily
recognized. ‘Two criteria should guide the ratings: (1) the pattern of
grazing over the different sites, and (2) the extent to which the soil
surface and small ground objects are masked from view by ungrazed
herbage. The first criterion is usually adequate for rating the degree of
grazing, but attention to the second helps evaluate the amount of herbage
left to protect the soil.

Under light utilization (fig. 18), grazing appears uniform over the
slopes; most spots are lightly cropped, but a few spots are cropped as
closely as 2-inch stubble height. The swale bottoms (wet-swale sites)
are closely cropped, often to a stubble height of less than 1 inch; swale
margins (dry-swale sites) show little use or a patchy use (fig. 19). Low-
hanging shrub canopies, fallen branches, and the edges of rocks are
mostly obscured by ungrazed herbage. The soil surface and small
objects on the ground are almost completely masked from view at distances
of 20 feet or more. The landscape has a yellowish or straw-colored cast
from ungrazed grass at the time of the first fall rains.

Under close utilization (fig. 20) grazing appears very uniform; few lightly
grazed tufts above 2-inch stubble height remain. Both the swale bottoms
(wet-swale sites) and the swale margins (dry-swale sites) are uniformly
grazed. Low-hanging shrub canopies, fallen branches, and the edges of
rocks stand out in bold relief, and the soil surface and small objects on
the ground are everywhere visible through the short stubble. There is
generally a brownish cast over the slopes from ungrazed filaree and other
broadleaved herbs at the time of the first fall rains.

Under moderate utilization (fig. 21) grazing appears very patchy;
lightly cropped spots are intermixed with spots cropped to about 2-inch
stubble height. The swale bottoms (wet-swale sites) are cropped to
less than 1-inch stubble height; swale margins (dry-swale sites) show
patchy use. Low-hanging shrub canopies, fallen branches, and the
edges of rocks are partially obscured by ungrazed herbage. The soil
surface and small objects on the ground are partially masked from view
at distances of 20 feet or more. The yellowish cast of ungrazed grass
is dulled in the closely grazed spots by the brownish undertones of dry
broadleaved herbs at the time of the first fall rains.

These photographic standards for recognizing and rating degree of
grazing of annual-plant vegetation, evolved by group effort of the range
staff, were tested in the experimental pastures and have proved adaptable
for use on almost all kinds of California foothill range.

SUMMARY

Annual plants, which dominate California foothill ranges, grow*from
fall until spring. Growth starts with the first effective rains (0.5 to 1.0
inch), usually in October, but is limited during the fall and winter by
intervals of low temperature or insufficient precipitation. Plants grow

46 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

F—447499
Figure 18.—Light utilization. This degree of grazing on California annual-plant
range maintains a good soil condition, early forage growth during the winter, and
full yields of a good plant mixture in the spring. Under very light grazing on some
ranges, however, wild oat or ripgut brome may increase to an undesirable amount.
While favorable for plant growth, light grazing leaves herbage that could be used
efficiently by cattle.

F—460562

Figure 19.—Pattern of swale utilization in lightly grazed range. The clovers and
rushes in the rather narrow swale bottom (wet swale) have been cropped to less
than l-inch stubble height; the heavy growth of grass (principally Mediterranean
barley) at the margin of the swale (dry swale) shows patchy use.

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 47

F—447500

FicurRE 20.—Close utilization. This uniformly close utilization of annual-plant
vegetation reduces the litter layer on the soil surface; conditions become distinctly
unfavorable to plant growth. Growth during the winter is retarded and total
yields in the spring are reduced, particularly on the very closely utilized bottom
lands. The percentage of the dominant species in the plant cover may not be
greatly changed, except in the swales; but minor weedy species increase on all sites.
This degree of grazing is too close for efficient cattle production.

F—447498
Figure 21.—Moderate utilization. This patchy use of annual-plant vegetation
maintains satisfactory soil conditions and a good plant mixture, without evidence
of deterioration in either. Winter growth of fone and total yields i in the spring
are satisfactory although not as great as under lighter grazing. This is an efficient
degree of utilization that provides satisfactory cattle production without waste of
herbage.

AS CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE

rapidly from February or March until the rains cease in April or May.
Then they mature rapidly and are dry during the hot, dry summers.

Thus, annual-plant range has three rather distinct forage periods:
(1) inadequate green forage during part of the fall and most of the winter;
(2) ample green forage during the spring; and (8) dry forage during the
summer and early fall.

Fitting ranch operation to forage growth—The range is grazed in other
periods than during the four spring months when there ordinarily is an
adequate, well-balanced forage supply. The foothills are the chief source
of grazing for cattle in California during most of the fall and winter, and
in many operations cattle are kept yearlong on foothill range. Efficiency
in use of the range can be increased by feeding of supplements during
the periods when the forage is deficient in quantity or quality and by
adopting management practices aimed at increasing the length of the
green-forage period.

The length of the critical forage period of fall and winter and the needs
for supplemental feeds usually cannot be predicted far in advance.
The average termination date for supplemental feeding, according to the
study, was near February 1; however, in years when rains sufficient to
start forage growth were delayed until mid-November, feeding was
needed until late February or early March.

The length of the adequate green-forage period is variable. For
example, this period at the experimental range varied in length from 72
to 176 days, with an average of 127 days for 14 years.

Most of the herbage is usually dry in June; occasionally in May. The
dry roughage consumed, mainly annual grasses, provides sufficient energy
but a supplemental feed is needed to provide protein. Bur-clover,
perennial bunchgrasses, or other plants, may serve as a partial supple-
ment during the summer on some ranges.

A management objective is to lengthen the period during which foot-
hill ranges provide well-balanced forage. Cultural practices for this
purpose are being developed for some soil and climatic conditions. Such
practices include reseeding or fertilization, to provide earlier green
forage in the winter and improved forage during the summer. Forage
will be adequate over a longer period if sufficient dry vegetation is left
each year to promote early plant growth and if each kind of range is
grazed at a time when it produces especially needed green forage. De-
ferring grazing of some range units, or portions of a single unit, until the
end of the spring growth period will allow cattle to select an improved
diet at that time and should delay the date when supplements are needed.
Deferring areas with considerable acreage of swales should be most
effective.

Adjusting ranch stocking to herbage production.—As an aid in stocking,
herbage production and grazing capacity can be estimated by a simple
classification of the different range sites. For example, in six experi-
mental pastures the grazing capacities estimated from classification of
the sites agreed closely with actual grazing results. The site classes were
recognized by characteristics of soil, topography, and waste area. This
method of land classification can be used in appraisal of California foothill
range.

Swales are the most productive of the site classes. In acres required
per animal-unit month, the grazing capacity of each site class in the
experimental pastures is as follows: swales, 0.5 to 0.7; gentle slopes

) USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 49

bordering the swales, 0.8 to 1.1; rolling slopes with few rock outcrops,
trees, or shrubs, 1.25 to 1.75; rolling to steep slopes with numerous rock
outcrops, trees, or shrubs, 2.0 to 3.0; and steep slopes with numerous
rock outcrops, trees, or shrubs, 3.0 to 5.0.. The lowest grazing capacity
was found on steep north slopes with a heavy canopy of trees and shrubs.

Ranch stocking must also consider the characteristic yearly fluctuations
in herbage production. On granitic soils at the experimental range, in
the 2 years with near-average total precipitation (16 to 20 inches),
herbage yields were average or greater. In wet years (more than 20
inches of precipitation), total yields were somewhat similar to those in
average years; most of the excess moisture was lost through seepage.

In dry years (12 to 16 inches of precipitation), rapid plant growth
during a short interval of favorable weather in the spring produced yields
that were only about 9 to 27 percent below the estimated 13-year average
of 1,640 pounds per acre. The effects of the occasional extreme drought
year (with less than 12 inches total precipitation) were not encountered
during the studies.

Fluctuations in the quantity of forage make advisable some adjust-
ments in livestock numbers nearly every year. The extent of needed
adjustments can be judged in late spring after most of the plant growth
for the year is complete. Changes in number of livestock will depend on
the average stocking and type of operation at each ranch.

Adjustments can be made by several measures in a mixed breeding-cow
and feeder operation. Enough cows and replacements can be carried to
utilize the herbage produced in dry years. The extra herbage in years of
average production is utilized by weaners. In years of above-average
production the increased yield can either be utilized by bringing in
outside animals or be left on the ground to replace any litter that may
be lost during dry years. This type of operation will permit the necessary
adjustments in livestock numbers in all except the occasional years of
extremely low forage production.

Most fluctuations in individual forage species exert relatively minor
effects on range stocking. The amount of grass in the plant mixture,
however, is of special importance on ranges grazed from summer until
winter. In years of very low grass production, stocking should be re-
duced from average or hay should be provided in addition to the short
supply of dry grass. |

A reserve of range forage cannot be carried over from year to year
because dry herbage of annual plants is ruined by leaching during the
winter. It appears desirable and feasible, therefore, to keep a reserve of
hay above usual yearly needs.

Selecting most efficient degree of grazing —Overstocking foothill range
lowers efficiency of production from a cattle breeding herd, according to
the conclusion of animal husbandmen of the University of California,
in charge of the livestock phases of the cooperative grazing-intensity
experiment. The objectives of efficient production — high calf crops
and optimum weaning weights — could not be met in the pasture under
heavy stocking for about 6 months (February to August), even with
moderate stocking for the remainder of the year. In the pasture stocked
slightly heavier than moderate, production was also reduced for unsupple-
mented cows but was not lowered for cows fed supplements during the 6
months they were out of the grazing-intensity pastures. Cattle produc-

50 CIRCULAR 870, U. 8S. DEPARTMENT OF AGRICULTURE

tion was satisfactory in all four of the experimental pastures grazed from
moderate to light from February to August.

Close grazing was clearly inefficient from the standpoint of forage
production also. Plant growth was always short during the winter on
range closely grazed during the preceding year, and in late winter forage
became adequate about 3 weeks later than on range grazed moderately
or lightly. Total herbage yield was also lower at plant maturity, par-
ticularly on the very heavily grazed bottom lands, the most productive
part of the range. Yield of each major species on slopes was lower, but
each composed about the same proportion of the total yield as under
moderate or ight grazing. There was some increase in weedy species of
low value under close grazing. Most important in the long run, close
grazing did not maintain sufficient litter on the soil surface to promote
full forage production year after year, and it produced other indications
of soil deterioration.

Light grazing resulted in the best soil-surface conditions and winter
growth of forage. It also maintained highest production of soft chess,
filaree, clovers, and other valuable forage species. But it left on the
ground a considerable bulk of herbage that could have been grazed to
increase cattle production.

An intermediate degree of grazing, between close and light, was the
most efficient. It maintained a satisfactory litter cover without apparent
soil deterioration. Winter growth of forage was also satisfactory, and
there was no significant decrease in amount of desirable forage species.
Keeping to a moderate degree of grazing on the average, with all practic-
able flexibility in numbers of livestock, appears feasible as a means of
obtaining efficient production from the fluctuating quantity of forage on
foothill ranges.

Condition of the soil surface on annual-plant range is best judged during
the winter. Where the layer of old herbaceous material is nearly absent
or of spotty occurrence over most of the range at this time of year, the
mineral soil will be readily apparent through a thin cover of new plants.
Conversely, under satisfactory conditions a fairly continuous thin layer
of litter and a thick carpet of vigorous new plants will leave almost no
bare soil apparent on most of the range. Accordingly, the extent of
herbaceous litter on the soil surface and the vigor of plant growth during
the winter are dependable guides to maintenance of satisfactory produc-
tion from the present cover of annual plants.

Photographic standards for judging degree of grazing of annual-plant
vegetation, developed and tested during the experiments, have been
used successfully in rating utilization on almost all kinds of California
foothill range.

COMMON AND BOTANICAL NAMES OF SPECIES

MENTIONED
Common name Botanical name
Alfilenasredstenm filarcesss. = = een Erodium cicutarvum (L.) L’ Her.
Baniey, Mediterranecanee = amputee eye Hordeum gussonianum Parl.
Bluegrass, pine_____ Ege REPO Ae ct MUN Me ES Oe! Poa scabrella (Thurb.) Benth.
ERROTNVES Wp Cults eS a ara 2 as eka Bromus rigidus Roth.
Bur-cloyverw@alitonntass= | see olen Medicago hispida Gaertn.
@ats-car Sin OOth= ite em nak eater ae eee Hypochoeris glabra L.

Chessiisottis 34s Meee 0 Cee ndek ye eas Bromus mollis L.

USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 51

(COG oe Ge a Ng pee ee a Trifolium spp.

Cloversittlehedda st. eh aka es Trifolium microcephalum Pursh

Cloverswhitetip se Che wee eee a Trifolium variegatum Nutt.

Wescueh foxtanle: hea 1 fai ye ois ae Festuca megalura Nutt.

Hiddleneck:: Douglas: = 22522 fs ee Amsinckia douglasiana DC.

POC tIAS Eee ter nee Nee Godetia spp.

Heronbill, big; broadleaf filaree__________- Erodium botrys Bertol.; E. botrys Bertol.
f. montanum Brumhard

Caterslendensesres fy oie A Avena barbata Brot.

Oat citer cvadetn Se Avena fatua L.

ROL OLS MES ALON en Le Le Pogogyne spp.

Popcorn-flower___________________---__--Plagiobothrys nothofoluus A. Gray

usherslimapodi cai: se 28 ls eb Juncus oxymeris Engelm.

curs ap OaGlene ee tase Be ON ach ed a Juncus bufonius L.

Silene, French (‘‘windmill pink’’)___-______ Silene gallica L.

Samish=clovyersmeseaes Sore ee Lotus americanus (Nutt.) Bisch.

Spikesedge, common_____________________Eleocharis palustris (L.) Roem. & Schult.

Stipas; needlegrasses_____________________Sttpa spp.

Singlamgrass scar naeeat iM Sorghum sudanense (Piper) Stapf.
Hitche.

Yellow-tarweed; hemizonia______________- Hemizonia virgata A. Gray

LITERATURE CITED

(1) Gorpon, AARON, AND SAMPSON, ARTHUR W.
1939. COMPOSITION OF COMMON CALIFORNIA FOOTHILL PLANTS AS A FACTOR
IN RANGE MANAGEMENT. Calif. Agr. Expt. Sta. Bul. 627, 95 pp.,
illus.

(2) GuiILBERT, H. R., anp Hart, G. H.
1946. CALIFORNIA BEEF PRODUCTION. Calif. Agr. Ext. Serv. Cir. 131, 157 pp.,
illus.

(3) Hart, G. H., GuinBEert, H. R., anp Goss, H.
- 19382. SEASONAL CHANGES IN THE CHEMICAL COMPOSITION OF RANGE FORAGE
AND THEIR RELATION TO NUTRITION OF ANIMALS. Calif. Agr. Expt.
Sta. Bul. 543, 62 pp., illus.

Waanon, K. A., AND GUILBERT, H. R.
1945. HOW MANY HEAD? OVERSTOCKING RANGE CUTS PROFITS IN CATTLE
PRODUCTION. Western Livestock Journal 23 (22): 19, 77-79, illus.

(5) Hormay, A. L.
1944. MODERATE GRAZING PAYS ON CALIFORNIA ANNUAL-TYPE RANGES. U.S.

Dept. Agr. Leaflet 239, 8 pp., illus.

(4)

AND FauseEtTt, A.

1942. STANDARDS FOR JUDGING THE DEGREE OF FORAGE UTILIZATION ON
CALIFORNIA ANNUAL-TYPE RANGES. Calif. Forest and Range Expt.
Sta. Tech. Note 21, 13 pp. illus. [Processed]

(6)

(7) Hutcuison, C. B., AND Kortox, E. L., et al.
1942. THE SAN JOAQUIN EXPERIMENTAL RANGE. Calif. Agr. Expt. Sta. Bul.
663, 145 pp., illus.

(8) JonEs, BuRLE J., AND Love, R. M.
1945. IMPROVING CALIFORNIA RANGES. Calif. Agr. Ext. Serv. Cir. 129, 48 pp.,
illus.

(9) TatBot, M. W., anp BisweE.u, H. H.
1942. THE SAN JOAQUIN EXPERIMENTAL RANGE: THE FORAGE CROP AND ITS
MANAGEMENT. Calif. Agr. Expt. Sta. Bul. 663: 13-49, illus.

(10) _____Biswe 1, H. H., Rows, P. B., anp Sampson, A. W.
1942. THE SAN JOAQUIN EXPERIMENTAL RANGE: OTHER STUDIES AND EXPERI-
MENTS IN THE PROGRAM OF THE SAN JOAQUIN EXPERIMENTAL RANGE.
Calif. Agr. Expt. Sta. Bul. 663: 136-142.

o2 CIRCULAR 8/70, U. S. DEPARTMENT OF AGRICULTURE

(11) Waenon, KENNETH A., AND BISWELL, H. H.
1943. TWO TYPES OF BROAD-LEAF ERODIUM IN CALIFORNIA. Madrono 7 (4):
118-125, illus.

(12) GUILBERT, H. R., AnD Hart, G. H.
1942. THE SAN JOAQUIN EXPERIMENTAL RANGE: EXPERIMENTAL HERD
MANAGEMENT. Calif. Agr. Expt. Sta. Bul. 663: 50-82, illus.

Hart, G. H., anp GUILBERT, H. R.
1947. WHEN AND HOW TO SUPPLEMENT THE DEFICIENT RANGE. Calif. Cattle-
man, March 1947, 12-13.

(13)

U. S. GOVERNMENT PRINTING OFFICE; 1951——935908