BLM LIBRARY
880499
•**-*
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-
Project Report
EFFECTS OF PINYON-JUNIPER CONVERSION
ON WATERSHED VALUES IN UTAH
Prepared by
Gerald F. Gifford
Utah Agricultural Experiment Station
in cooperation with
Bureau of Land Management
April l, 1963
*
O e^%.o.|° c o^
•
^
#
•
Title of Study : "Effects of Pinyon-Juniper Conversion on Watershed Values
in Utah"
Objectives :
A. To determine the water budget of natural stands of pinyon-juniper and
adjacent areas which have been cleared and/or seeded.
B. To determine the effects of vegetation conversion on soil physical
properties and soil stability.
C. To ecologically evaluate sites before and after as to phenology,
composition, and production of vegetation.
D. To evaluate the economics of conversion practices in terms of the
watershed values and multiple use relations.
E. To obtain data necessary for determination of hydrologic soil cover
complexes on the study sites.
Introductory Comment : This report is concerned with additional data analysis
and compilation which has resulted since the project report dated January 1,
1969. As before, the report will provide information to supplement previous
reports as well as indicate progress to date.
Infiltrometer Studies : Data from the second phase of the two-year study
utilizing the Rocky Mountain infiltrometer on several treated (and nearby
untreated) P-J sites in central and southern Utah are still being analyzed.
However, some information is now available and is presented below.
METHODS
A Rocky Mountain infiltrometer (Dortignac, 1950 was utilized to simulate
high intensity (three in./hr. or greater) rainfall on plots approximately two
and one-half square feet in area. Fourteen treated and nearby untreated
•
pinyon-junfper sites near Blanding and Milford, Utah were sampled with 325
infiltrometer plots during the summer of 1968. Tables 1 and 2 give a brief
description of each site.
The experimental procedures were identical to those already described
by the authors (Williams, Gifford, and Coltharp, 1969) .
Soils in the study sites were derived from colluvium, alluvium, residium,
and eolian of mainly sedimentary and volcanic rocks (Milford area) and sand-
stones and shales (Blanding area).
Pinyon- juniper sites near Blanding Utah
Table 3 shows mean infiltration rates (?n./hr.) during specified time
intervals and Figure 1 denotes relative differences in sediment production from
treated and nearby untreated conditions on six pinyon-juniper sites studied
near Blanding, Utah. As noted from Table 1, age of treatment varied from 1
to 6 years.
U.S.U. (Utah State University) study site . No significant differences in
infiltration rates are indicated between treated and untreated conditions
during any time interval on the area double chained with debris in place
(item 1, Table 3). However, on the area with debris windrowed, the untreated
area showed significantly higher infiltration rates during the time interval
8 to 18 minutes following start of simulated rainfall. There were no significant
differences between treated and untreated areas with regard to sediment
production.
Area 1**9. Brush Basi n ,, Peters Point #1, and Peters Point #2 . No
significant differences between treated and untreated conditions are indicated
for either infiltration rates (Table 3) or sediment yields (Figure 1).
Alkali Ridge . At the Alkali Ridge site, the following four exclosures
were located within the treated area: (1) everything excluded, (2) rabbits
i r t-
•
Table/ . Brief description of study sites near Blanding, Utah.
Date
Project
Location Seeded—
1/
1. Pelens Point
Location #1—
chained
and debris in
place
Location #2
' chained
and debris in
place
T32S R23E 1964
Sections Ik,
15, 22, 23
T32S R23E I960
Sections 31,
32
Seed
Type lbs/acre
Crested
Wheatgrass
Crested
Wheatgrass
Average
Production
in 1965
(lbs/acre
dry weight)
Unknown
Unknown
Elevation-
(feet)
2/
7,000
7,000
Annual-
Precipitation
(inches)
lk
Ik
Grazing History-
Negligible summer use
before treatment. After
treatment light summer
use except heavy use
around water.
Same as #1
2. Brush Basin
Double chained
and debris in
place
3. Alkali Ridge
Double chained
and debris in
place
k. Job #1^9
chained
and debris in
place
T35S R22E 1962
Sections 20,
29
T36S R23E 1961
Sections 25,
26, 35, 36
T37S R22E 1963
Sections 5, 6,
7, 8
Crested
Wheatgrass
Unknown
Crested 6 -Unknown
Wheat grass
Crested 6
Wheatgrass
(Four- wing saltbush Unknown Unknown
and yellow sweet-
clover)
7,000
6,000
6,000
16 Before treatment negligible
use after treatment
stocked at 5ac/AUM.
11-12
11-12
Negligible use before
treatment, after treat-
ment stocked at ^ac/AUM.
No grazing until 1969.
Table / . Continued.
Project
Location
Date ,
Seeded- 7
5. Utah State University-
Study plots
Location #1
chained
and debris in
place
Location #2
chained
and windrowed
Same
Same
1967
1967
Seed
Type lbs/acre
Crested
Wheatgrass
Same as #1
Average
Production
in 1965
(lbs/acre
dry weight)
2/
Elevation—
(feet)
New job
New job
6,500
6,500
3/
Annual-
Precipitation
(inches)
11-12
11-12
Grazing History
No grazing.
No grazing
- Seeded in fall unless otherwise indicated.
2/
Elevations gxven on all sites were taken from United States Geological Survey quadrangles (15 minute series)
- Annual precipitation values taken from the annual normal precipitation map for the State of Utah (1931-1960)
V
- Windrowed sites were drill seeded and non windrowed sites were broadcast seeded
Table eR. . Brief description of study sites near Milford, Utah.
Date
Average
Production
in 1965
Project
Location Seeded—
V
Seed
Type
(lbs/acre Elevation-'
lbs/acre wet weight) (feet)
2/
l.o Indian Peaks
L./
Location #1-' ; ' T30SR 17V/ . 1964
chained Sections 9,
and windrowed 10
Pubescent
Wheatgrass
6
2000
6,500-7,000
Location #2
chained
and windrowed
Location #3
chained
and debris in
place
Location #4
chained
and windrowed
2. New Arrowhead
mine.
chained and
windrowed
V
T30S H17W I960
Section 7
T30S Kl8w
Section 12
T29S R18W
Sec 23, 24,
25,26
Intermediate 6
Wheatgrass
3000
6,500-7,000
T30S R17W
Section 27
T31S R17W
Sec 6, 7
T31S Rl8w
Sec 1, 12
1961
1962-64
Pubescent
Wheatgrass
Intermediate
Wheatgrass
2000
6,500-7,000
6,400-6,800
6 1,200-1,600 7,500-8,000
Annual-
Precipitation
(inches)
10
11
12
11
15
Grazing History
Grazed in spring, summer
and fall before treatment
grazed in mid and late
summer in rotation
system after treatment.
Grazed in spring, summer
and fall before treatment
grazed in late spring and
early summer in a rotation
system after treatment.
Same as #1
Before the area was
treated grazing use was in
conjunction with private
land to the west. Very
little use because of the
heavy trees and lack of
feed. The seeding is now
used from June 15 to August
3f. In 1968 it was used
until August in.
Table ^^ . Continued.
Project
Location
Date 1 /
Seeded-
3. Jockeys
chained
and windrowed
T30S H15W 1958
Sec 20, 21,
28, 29
4.
Indian Creek T28S R?W 1959
Conservation Area Sec 26, 27
chained
and windrowed
5.
Utah State I 30S KL5W
University study Sec 18, 19
sites, chained and T30S KL6W
one-half windrowed Sec 13 t 2h
and one-half debris
in place
1967
Seed
Type lbs/acre
Crested
Wheatgrass
Crested
Wheatgrass
Crested
Wheatgrass
Average
Production
in 1965
(lbs/acre
wet weight)
Elevation—
(feet)
2000
2000
6,500-7,000
6,000-6,500
New
7,000
3/
Annual-
Precipitation
(inches)
12+
12
12
Grazing History
Grazed year around before
treatment - grazed only
in spring and early
summer after treatment.
Grazing spring and
summer before treatment -
after treatment it is
grazed in rotation system
with few numbers. Cattle
are put in when grass is
considered ready.
— Seeded in fall unless otherwise indicated
2/
3/
V
Elevations given on all sites were taken from United States Geological Survey quadrangles (15 minute series)
Annual precipitation values taken from the annual normal precipitation map for the state of Utah (1931-1960)
Windrowed sites were drill seeded and non windrowed sites were broadcast seeded
- -vi
Table 3. Mean infiltration rates (in./hr.) during specified time intervals (minutes) on various pinyon- juniper sites near Blanding, Utah.
Site y
3-4
4-5
5-6
6-7
7-8
8-13 13-18
18-23
23-28
28-33
33-38
USU study site T 4.2
(Debris in place) U 3.9
USU study site T 4.2
(Debris windrowed) U 3.9
Area 149
Brush Basin
T 3.2
U 3.8
T 3.0
U 2.7
Alkali Ridge T 3.9
(everything except U 3.0
deer excluded) »
Alkali Ridge T 3.6
(everything U 3.0
excluded)
Alkali Ridge T 3.3
(Including cattle) U 3.0
Alkali Ridge T 3.4
(excluding every- U 3.0
thing except deer
and rabbits)
4.0
3.7
3.6
3.9
3.3
3.9
3.4
3.8
3.4
3.4
2.6
3.2
2.4
2.7
2.4
2.6
2.3
2.6
2.3
2.6
4.2
3.7
4.0
3.9
3.7
3.9
4.0
3.8
3.0
3.4*
2.6
3.2*
2.6
2.7
2.5
2.6
2.5
2.6
2.5
2.6
3.8
3.9
3.6
3.8
3.1
3.5
3.4
3.4
2.1
2.7
2.1
2.3
2.0
2.2
1.8
2.2
1.8
2.2
1.8
2.2
2.8
2.3
2.6
2.6
2.4
2.3
2.2
2.1
1.8
1.8
1.4
1.5
1.4
1.6
1.4
1.5
1.4
1.5
1.4
1.5
3.8
2.9
3.7
2.9
3.7*
2.7
3.3
3.0
2.9**
1.7
2.4**
1.5
2.3**
1.4
2.2**
1.4
2.2**
1.4
2.2**
1.4
3.6
2.9
3.4
2.9
3.4
2.7
3.5
3.0
2.7*
1.7
2.1*
1.5
1.9*
1.4
1.7
1.4
1.8
1.4
1.8
1.4
3.1
2.9
3.0
2.9
3.0
2.7
2.9
3.0
2.3*
1.7
2.0*
1.5
1.9*
1.4
1.9*
1.4
1.8*
1.4
1.8*
1.4
3.4
2.9
3.4
2.9
3.1
2.7
3.0
3.0
2.4
1.7
2.1
1.5
2.1*
1.4
2.0
1.4
2.0
1.4
1.9
1.4
Table 3. Continued.
Site -
3-4
k-3
5-6
6-7
7-8
8-13
13-18
18-23
23-28
28-33
33-38
Alkali Ridge
I
3.7
3.8
3.6
3.1
2.8
2.0
1.6
1.5
1.5
1.5
1.5
(excluding every-
U
3.0
2.9
2.9
2.7
3.0
1.7
1.5
1.4
1A
1A
lA
thing except
rabbits)
Peters Point
T
k.o
3.6
2.6
2.7
2A
1.5
lA
l.k
1A
1A
lA
#1
U
k.6
3A
3.0
3.0
2.7
1.8
1.6
1.6
1.5
1.5
1.5
Peters Point
T
k.O
3.6
3.**
2.8
2.7
1.9
1.8
1.7
1.6
1.6
1.6
#2
U
k.G
3A
3.0
3.0
2.7
1.8
1.5
1.6
1.5
1.5
1.5
- See Table 1 for a brief description of sites.
* Significantly larger at 5% than other value in pair.
** Significantly larger at 1% than other value in pair.
2.S-,
1-5.
.69
Q.S.
.35
.27 I— I
.28
Treated
' I Untreated
n.s.
1.09
.96
.65
P < .05
.65
.15
JSU Study Sited BSD Study ' Area 1^9 "Brush Basin "Alkali Ridge Alkali Ridge
(D in place) Sites (Deer only) (Nothing)
(D Windrowed)
n.s. indicates no significant difference between treated and untreated.
2.5,
£ 2.0-
!
1.5-
1.0.
0.5.
0.0
.65
.51
P < .05
.65
.15
.65
.73
.35
^.
Treated
I ' Untreated
.73
Alkali Ridge 'Alkali Ridge 'Alkali Ridge "Peters Point "Peters Point
(Cattle) (No Cattle) (Rabbits only) #1 «
n.s. indicates no significant difference between treated and untreated.
Fig. 1. Sediment yield from six P-J sites near Blanding, Utah.
only, (3) deer only, and (h) deer and rabbits only. As noted in Table 3,
infiltration rates were significantly greater after approximately 6 minutes
of simulated rainfall in the deer only exclosure and on the treated area
(outside exclosures) after 8 minutes. Similarly, in the exclosure excluding
everything, a significantly higher infiltration rate was observed during the
8 to 23 minutes time interval. A significantly higher infiltration rate is
indicated for the deer and rabbit only exclosure during the time interval
between 18 and 23 minutes. No significant differences were noted in infiltration
rates between treated and untreated conditions pertaining to the rabbits only
exclosure.
As noted in Figure 1, sediment yields are significantly greater from
untreated conditions than from the deer and rabbits only exclosure and the
everything excluded exclosure. No significant differences are signified
between any other treated or untreated conditions.
Pinyon- juniper sites near Milford, Utah
Table k shows mean infiltration rates during specified time intervals and
Figure 2 denotes relative differences in sediment production from treated and
untreated conditions on eight sites near Milford, Utah.
Arrowhead Mine and Indian Peaks #1, 2, 3, and k . As noted in Table k the
infiltration rate during the 3 to k minute time interval on Indian Peaks #1
site was significantly greater on the untreated area. No significant differences
in infiltration rates between treated and untreated conditions were demonstrated
for any other time intervals on Indian Peaks numbers 1, 2, 3, and k, or Arrow-
head Mine. Also, as noted in Figure 2, there were no significant differences
between treated and untreated conditions with respect to sediment production
on any of the above areas.
U.S.U. study site. No significant differences in infiltration rates are
I
Table 4. Mean infiltration rates (in./hr.) during specified time intervals (minutes) on various pinyon- juniper sites near Milford, Utah
Site
1/
3-4
4-5
5-6
6-7
7-8
8-13 13-18
18-23
Indian Peaks
#1
T
U
3.1
3.9*
2.5
3.2
2.3
2.7
2.2
2.2
2.0
2.2
1.7
1.8
1.6
1.7
1.5
1.6
Indian Peaks
#2
T
U
3.6
4.o
2.6
3.3
2.2
2.8
1.9
2.3
2.0'
1.2
1.8
1.8
1.7
1.8
1.6
1.7
Indian Peaks
#3
T
U
4.2
5.4
3.9
4.9
4.8
5.1
4.4
4.9
4.3
4.7
3.9
4.2
3.8
4.0
3.7
3.9
Indian Peaks
#4
T
U
3.2
4.0
2.4
3.4
3.2
3.1
2.6
2.6
2.5
2.7
1.8
2.5
1.4
2.3
1.3
2.1
Jockeys
T
U
4.1**
2.0
4.1**
1.8
3.0**
1.7
3.2**
1.5
3.0**
1.6
2.9**
1.3
2.8**
1.0
2.7**
1.0
USU study site
(Debris in place)
T
U
3.1
3.5
2.6
3.0
2.5
2.9
2.2
2.7
2.2
2.7
1.6
2.2
1.6
2.1
1.5
2.1
USU study site
(Windrowed)
T
U
2.6
3.5
2.4
3.0
2.4
2.9
2.3
2.7
2.2
2.7
1.8
2.2
1.4
2.1*
1.5
2.0*
Indian Creek
T
U
3.8
3.8
3.1
3.7
2.6
3.7*
2.2
3.0
2.1
3.0
1.6
2.6*
1.3
2.2*
1.2
2.0*
Arrowhead Mine
T
U
4.o
3.6
4.0
3.6
3.2
3.5
3.0
3.1
2.7
3.7
2.8
2.7
2.6
2.6
2.5
2.3
23-28
28-33
33-38
1.5
1.6
1.5
1.7
1.5
1.7
1.6
1.7
1.6
1.7
1.6
1.7
3.9
4.0
3.9
4.0
3.9
4.0
1.3
2.1
1.3
2.1
1.3
2.1
2.8**
1.0
2.9**
1.0
2.9**
1.0
1.5
2.0
1.4
2.0
1.4
2.0
1.5
2.0*
1.5
2.0
1.5
2.0
1.3
2.0*
1.2
2.0*
1.2
2.0*
2.5
2.4
2.5
2.3
2.5
2.3
1/
See Table 2 for a brief description of sites.
Significantly larger at 5% level than other value in pair.
Significantly larger at 1% level than other value in pair.
2.5-.
9
•■-.•t
0.5-
n.s
.39
n.s.
.32 .33
.26
.16
n.s.
.35
Indian Peak I Indian Peak ' Indian Pe
#1 \Z #3
1
.28
filsila Treated
I I Untreated
ak l Indian Peak * Jockeys I
n.s, indicates no significant difference between treated and untreated.
•
2.5'
1.5
0.5'
n.s.
.28
.15
P < .01
.38
si .is
UsUStudy
icy t UJiO Slud)
J Treated
I I Untreated
n.s.
.12 .10
n
iy ( Indian Creeic * 'Arrowhead 1
Sites Conservation Mine
Area
n.a. indicates no significant difference between treated and untreated.
•
Fig. 2. Sediment yield from eight P-J sites near Milford, Utah.
shown (Table k) between the double chain with debris in place treatment and the
untreated area. The area with debris windrowed shows a significantly lower
infiltration rate during the time interval 13 to 28 minutes following start of
simulated rainfall. No significant differences in sediment yields occurred on
either area.
Jockey ' s . The treated area shows significantly higher infiltration rates
for all time intervals during simulated rainfall. Also, and somewhat
unexpectedly, a significantly higher sediment yield is shown for the treated
condition.
Beaver . In contrast to the Jockey's area, the untreated area shows
significantly higher infiltration rates during the 5 to 6 minute time interval
and all time intervals after 8 minutes of simulated rainfall. No significant
differences in sediment yields are apparent between treated and untreated
conditions .
SOME TENTATIV E CONCLUSIONS
Infiltration and sediment data collected with a Rocky Mountain
infi Urometer on ]k sites in southern Utah indicate that areas cleared of
pinyon-juniper trees and seeded to grass show no consistent decrease or increase
in sediment yields or infiltration rates at a given point. Of 14 sites studied,
three indicated decreased infiltration rates on the treated portion and two
sites indicated increased infiltration rates on the treated area. Nine sites
showed no significant differences in infiltration rates between the treated and
untreated conditions. As for sediment yields, one site had significantly less
sediment yield from the treated area and two sites had significantly higher
sediment yields from the treated areas.
These findings are similar to the results recently reported from study of
14 sites in central Utah by the authors. After study of 28 sites
(approximately 550 inf i ltrometer plots) involving pinyon-juniper conversion
practices and associated point changes in watershed values, it may be concluded
that infiltration and erosion rates at a given point are not particularly
affected as a result of treatment practices. If there is an effect, it may be
either positive or negative.
It is well known that many biotic, edaphic and climatic variables interact
to determine infiltration and erosion rates at a point on given landscapes.
All of the above data will be further analyzed to determine those factors
important in determining or predicting infiltration rates and sediment yields
on each inf i ltrometer plot. Such analyses should aid in future predictions of
the effect that certain vegetation conversion practices have on watershed
parameters .
Future inf i ltrometer studies should concentrate on seasonal variations
in infiltration and sediment production rates as well as the effect of
anticedent moisture conditons, varied rainfall intensities, and grazing (and
particularly trampling) on such values.
Soil Studies . A copy of the manuscript entitled "Influence of Pinyon-Juniper
Conversions and Water Quality on Permeability of Surface Soils'" is to be found
in the Appendix B. The paper is scheduled for publication in the August
issue of Water Resources Research .
Runoff Plot S tudies, Blanding Area. Data from the storm of 7-28-68 (see Table 1,
January 1, 1969 Project Report) was not included in the January 1 report.
Table ^Dg'w/es runoff values for the chain and windrow treatment and control
on a paired plot basis. Mean runoff from the chain and windrow treatment was
0.07 area inches compared with 0.02 area inches from the control plots. The
•
able «
Runoff data (area inches) from Blanding chain and windrow plots
(0.11 acre) and control plots for storm of 7-28-68 (0.45 inches total
precipitation) .
Treatment
Difference
D - X l - X 2
Deviation
d ■ D - d
Squared
Plot
No.
Windrow
X l
Control
x 2
Deviation
d 2
1
.02
.01
+.01
-.04
.0016
2
.16
.05
+ .11
+.06
.0036
5
.02
.01
+.01
-.04
.0016
4
.13
.01
+.12
+.07
.0049
5
.02
.01
+ .01
-.04
.0016
Total
.35
.09
.26
.0133
Mean
.0133
if
.07
.02
a = .05
K-
- .0033
S D
= /.0033 =
.057
h-
.057
1724"
= .025
t
.05 -
" .025
2.0
(.20
> p > .10)
1.00 .
in
J!
0.50 .
0.25 .
.09
.03
P< .05
Blandinq Study Site
.09
p-C .01
Storm of 7-30-68
(0.h5 inches)
.52
p <:. io
n
p<.So
Storm of 8-5-68
(1 .^5 inches)
~ o
•
difference is significant at the .20 level of probability. There was no
measurable sediment.
There was no measurable sediment or runoff from the double chaining with
debris in place treatment for the 7-28-68 storm.
Runoff Plot Studies, Milford Area . Several runoff-producing storms occurred
at the Milford site during the summer, but only those plots which were
completed at the time of a storm provided runoff and sediment data. Runoff
data has been analyzed for the storms of 7-30-68, 7-31-68 and 8-8-68 for the
chain and windrow runoff plots only. Runoff plots in the double chaining with
debris in place treatment were not completed until mid-August and therefore,
runoff data from these plots are fragmentary. Respective controls were not yet
installed either, so such data are omitted here. No runoff events occurred
after 8-8-68.
Precipitation records . Table J? given rainfall data through October 3
when runoff recorders were shut down.
Storm of 7-30-68 . Table _/_ gives runoff values for the chain and windrow
treatment and control on a paired plot basis. Mean runoff was 1.27 area inches
from the chain and windrow treatment plots compared with 0.77 area inches from
the control plots. The difference is significant at the .10 level of probability,
It may appear that runoff is unusually high from at least three of the
runoff plots in the chain with windrow treatment. However, it should be noted
that the storm was of fairly high intensity throughout the duration of most
of the rainfall. In addition, surface soils were very moist due to cloudy
conditions and rain which had fallen on each of the preceeding eight or nine
days. Such conditions would promote high runoff rates.
Sediment records were not good due to sampling problems.
Table fe> . Precipitation data from Milford pinyon-juniper study site.
Date
Time Storm
Began (MST)
Total Rainfall
(inches)
Average Intensity
(in/hr.)
7-8-68
Rainfall reco
rds
started
7-21-68
6:30 p.m.
0.05
....
7-22-68
12:30 p.m.
0.15
7-23-68
2:30 a.m.
0.10
7-23-68
9:00 p.m.
0.10
7-23-68
11:00 p.m.
0.30
0.30
7-24-68
10:30 a.m.
0.05
7-25-68
10:30 a.m.
0.55
0.55
7-27-68
9:00 p.m.
0.15
7-28-68
1 :30 a.m.
0.05
7-29-68
10:30 a.m.
0.05
__„„
7-30-68
3:30 p.m.
1.65
(based on
f!
2.40
rst 1.50" of rainfall
7-31-68
12:15 P.m.
0.60
(based on
fi
0.80
rst 0.40" of rainfall
8-2-68
9:00 a.m.
0.10
„«.„„
8-2-68
4:00 p.m.
0.10
8-5-68
1 :00 p.m.
0.05
8-8-68
1:15 p.m.
0.70
0.15
8-10-68
5:30 p.m.
0.10
....
8-13-68
12:30 p.m.
0.20
8-22-68
4:00 a.m.
0.15
9-4-68
1 :30 p.m.
0.10
—.-._
9-29-68
2:30 a.m.
0.15
10-3-68
Storage gage
charged
- recording gages s
hut
down
*7
Table f . Runoff data (area inches) from Milford chain and windrow plots
(0.11 acre) and control plots for storm of 7-30-68 (1.65 inches
total precipitation).
Treatment
Difference
D = X ] - X 2
Deviation
d = D - d
Squared
Plot
No.
Windrow
X l
Control
X 2
Deviation
d 2
1
1.51
0.35
+ 1.16
+0.66
.4356
2
1.53
1.21
+0.32
-0.18
.0324
3
1.45
1.40
+0.05
-0.45
.2025
4
0.72
0.54
+0.18
-0.32
.1024
5
1.15
0.35
+0.80
+0.30
.0900
Total
6.36
3.85
+2.51
.8629
Mean
1.27
0.77
d = 0.50
s 2 m J&29 = >2157 s d = /.2157 = .46
s d = fW" - 205 * = -^fot -2 = 2M (.10> P >.05)
Storm of 7-31-68 . Table K shows a mean runoff of 0.19 area inches from
chain and windrow treatment compared with 0.12 area inches from control plots.
The difference is significant at the .20 level of probability.
Sediment records were not good due to sampling problems.
Storm of 8-8-68 . Table J * shows a mean runoff of 0.07 area inches from
chain and windrow plots as compared with 0.02 area inches from control plots.
The difference is significant at the .20 level of probability.
There were no measurable sediment yields.
Additional Comments . Line intercept data concerning tree, shrub and ground
cover of the Milford runoff plots are given in Table /O. Blanding runoff
plot cover characteristics will be forthcoming in the next report.
able
{f . Runoff data (area inches) from Milford chain and windrow plots and
control runoff plots for storm of 7-31-68 (0.60 inches total
precipitation) .
Plot
No.
Treatment
Windrow
X,
Control
X„
Difference
C 2
D^ - )
Deviation
Deviation
d = D -
a
d 2
+0.14
.0196
+0.03
.0009
-0.02
.0004
+0.01
.0001
-0.03
.0009
•
1
.30
.09
2
.39
.29
5
.13
.08
k
.05
.11
5
.09
.05
Total
0.96
0.62
Mean
0.19
0.12
.2
ID "
.0219
k
Z2
0055
S d = 2T2? = * 033
+ .21
+ .10
+ .05
- .06
+ ,0k
+0.3^
3 = 0.07
S D = ( A0055 = .07^
_ .07 - _ 2 , 2
* .033 " 2 * 12
.0219
(.20 > p > .10)
able
Runoff data (area inches) from Milford chain and windrow plots
(0.11 acres) and control plots for storm of 8-8-68 (0.70 inches total
precipitation.
Treatment
D
D
ifference
= X l " X 2
Deviation
d - D - d
Squared
Plot
No.
Windrow
X l
Control
X 2
Deviation
d 2
1
0.15
0.06
+0 . 09
-10.04
.0C16
2
0.17
0.05
+0 . 1 2
+0.07
.0049
3
0.02
0.01
+0 c 1
-0.04
.0016
j.
0.02
. GO
+0.02
-C.03
.0009
5
0.00
0.00
0.00
-0.05
.0025
Total
0.36
0.12
. 24
.0115
Mean
0.07
0.02
d
= 0.05
~-^ = .0029
.054
2.24
,024
s D = /.C029 = .054
t = • G5 " f)f ° - 2.08 (.20 > p > .10)
Table / . Tree shrub and ground cover (percent) on runoff plots at the Milford
study site, September, 1968.
Plot
Transect. ,
Number —
Percent Cover
Tree
Shrub
Ground —
Windrow
# 1
1
19 ft.
0.00
0.00
p
Agcr
L
Phho
R
BG
90.25
2.28
0.57
0.19
2.66
4.05
2
33 ft,
0.00
0.00
P
Agcr
L
Phho
B
BG
79.80
0.57
3.80
0.19
8.30
7.34
3
7k ft.
0.00
0.00
p
Agcr
L
BG
91.01
0.57
4.75
3.67
0.00
0.00
p
Agcr
L
Phho
R
BG
87.02-
1.14-
3.04-
0.13
3.65
5.02-
Windrow
# 2
1
19 ft.
0.00
0.00
P
Agcr
L
Annuals
R
BG
Lupine spp.
3.00
2.20
5.00
0.60
0.20
88.40
0.60
2
33 ft.
0.00
0.00
p
Agcr
L
Annuals
R
BG
Phho
Misc.
0.00
0.41
19.98
0.41
0.41
77.57
0.61
0.61
— Line Transects across runoff plots at indicated distances measured from top
of plot.
2/
— P = pavement
L = litter
R = rock
BG = bare ground
•
Table /O.
Continued.
r
Transect ,
Number -
Percent Cover
Plot
Tree
Shrub
Ground —
3
7k ft.
o.oo
0.00
p
Agcr
L
BG
Annuals
B
0.00
0.67
14.69
83.75
0.22
0.67
0.00
0.00
p
Agcr
L
BG
Annuals
Phho
R
Lupine spp.
Misc.
1.00
1.09
13.22
83.48
0.4i
0.20
0.20
0.20
0.20
Windrow
# 3
1
19 ft,
0.00
0.00
p
Agcr
L
BG
Lupine spp.
37.82
1.53
2.88
56.81
O.96
2
33 ft.
0.00
0.00
p
Agcr
L
BG
Lupine spp.
R
13.05
1.34
4.60
78.71
2.11
0.19
3
74 ft.
0.00
0.00
p
Agcr
L
BG
Lupine spp.
R
Annuals
0.00
1.71
0.95
94.49
2.4-7
0.19
0.19
X
0.00
0.00
p
Agcr
L
BG
Lupine spp.
R
Annuals
16.96
1.53
2.81
76.66
1.85
0.13
0.06
Table /O.
Continued.
»
Transect.. /
Number -
Percent Cover
Plot
Tree
Shrub
Ground -
Windrow
# k
1
19 ft.
0.00
0.00
p
Agcr
L
BG
Annuals
95.21
1.92
2.68
0.00
0.19
2
33 ft.
0.00
0.00
p
Agcr
L
BG
88.32
0.76
7.87
3.03
3
7k ft.
0.00
0.00
p
Agcr
L
BG
Ann C
Penst,
Rock
spp.
45.12
1.97
3.27
48.69
0.19
0.38
0.38
0.00
0.00
P
Agcr
L
BG
Ann
Penst.
Rock
spp.
76.22
1.55
if. 61
17.23
0.13
0.13
0.13
Windrow
# 5
1
19 ft.
0.00
0.00
P
Agcr
L
BG
Lupine spp.
a
0.00
0.57
2.68
93.88
0.38
2.49
2
33 ft.
0.00
0.00
P
Agcr
L
BG
R
0.00
1.15
0.38
96.55
1.92
3
74 ft.
0.00
0.00
p
Agcr
L
BG
Annuals
R
0.00
1.53
0.76
92.15
0.19
5.37
Table
/o.
Continued.
Transect. /
Number —
Percent
Cover
Plot
Tree
Shrub
Ground -
X
0.00
0.00
P
Agcr
L
BG
Annuals
B
Lupine spp.
0.00
1.08
1.27
94.20
0.06
3.26
0.13
Windrow
1
Juos
29.38
0.00
P
43.50
Check # 1
19 ft.
L
BG
Lupine spp.
Opuntia
Phho
50.19
5.74
0.19
0.19
0.19
2
Juos
12.16
0.00
P
62.16
33 ft.
L
BG
Annuals
34.79
2.86
0.19
3
0.00
0.00
P
83.58
?4 ft.
L
BG
Sihy
Chvi
13.20
2.86
0.18
0.18
X
Juos
13.85
0.00
P
L
BG
Annuals
Opuntia
Phho
Sihy
Chvi
63.08
32.73
3.89
0.06
0.06
0.06
0.06
0.06
Windrow
1
Pimo
17.24 Artr 0.19
P
25.77
Check # 2
19 ft
Juos
4.26
L
BG
R
61.24
0.19
12.80
2
Pimo
8.84
0.00
P
25.73
33 ft.
Juos
15.71
L
BG
R
67.19
6.50
O.58
•
Table /l/< C
ontinued.
Transect. ,
Number -
Percent
Cover
Plot
Tree
Shrub
Ground -
3
74 ft.
Pimo
Juos
1.16
29.87
Artr
3.68
P
L
BG
R
21.14
50.82
27.85
0.19
X
Pimo
Juos
9.08
16.61
Artr
1.29
P
L
BG
R
24.21
59.75
11.51
4.53
Windrow
Check # 3
1
19 ft.
Juos
40.28
Artr
0.95
P
L
BG
Phho
3.80
22.42
72.64
1.14
2
33 ft
Juos
Pimo
6.65
45.03
0.00
P
L
BG
40.85
43.89
15.26
3
74 ft
Juos
47.31
0.00
P
L
BG
R
Chvi
5.70
34.77
57.06
0.38
2.09
X
Juos
Pimo
31.41
15.01
Artr
0.32
P
L
BG
R
Phho
Chvi
16.78
33.69
48.33
0.13
0.38
0.69
Windrow
Check # 4
1
19 ft.
Pied
Juos
3.04
7.03
Artr
3.80
P
L
BG
R
55.29
18.24
26.09
0.38
2
33 ft.
Pimo
Juos
15.70
7.98
Artr
1.33
P
L
BG
56.43
35.72
7.85
3
74 ft
Juos
Pied
15.39
37.62
Artr
5.32
P
L
BG
30.97
60.61
8.42
•
Table A'.
Continued.
Transect.. /
Number -
Percent
Cover
Plot
Tree
Shrub
Ground —
X
Pied
18.79
Artr
3.48
P
47.56
Juos
10.13
L
BG
E
38.19
14.12
0.13
Windrow
1
Pied
34.77
0.00
P
42.75
Check # 5
19 ft.
L
BG
Opuntia
45.60
11.46
0.19
2
Pied
34.20
0.00
P
48.64
33 ft.
Juos
6.08
L
BG
Opuntia
49.97
O.63
0.76
3
Juos
23.75
Artr
4.56
P
55.48
74 ft.
L
BG
Phho
4l. 61
2.15
0.76
X
Pied
22.99
Artr
1.52
P
48.96
Juos
9.94
L
BG
Opuntia
Phho
45.73
4.74
0.32
0.25
Debris
1
Juos
24.95
Artr
12.76
P
45.33
Check # 1
19 ft.
L
BG
Sihi
Phho
49.52
4.58
0.19
0.38
2
Juos
14.67
Artr
4.77
P
42.94
33 ft.
Pimo
22.52
Arno
8.40
L
BG
Sihi
Phho
Annuals
54.58
0.00
1.72
0.38
0.38
3
Pied
45.64
Artr
8.16
P
30.61
1
74 ft.
Arno
3.52
L
BG
Phho
Sihi
Annuals
65.49
3.15
0.19
0.37
0.19
•
JTable /f .
Continued.
Transect
Number
•
1/
Percent
Cover
Plot
Tree
Shrub
Ground =
X
Juos
13.21
Artr
8.56
P
39.63
Pimo
7.51
Arno
3.97
L
56,53
Pied
15.21
BG
Phho
Sihi
Annuals
2.57
0.32
0.76
0.19
Debris
Check # 2
1
19 ft.
Juos
8.02
Artr
Arno
1.68
3.73
P
L
BG
Phho
Sihi
67.54
22.76
8.96
0.37
0.37
2
Juos
32.65
Artr
5.97
P
46.27
33 ft.
Arno
2.24
L
BG
Phho
Sihi
40.86
12.31
0.56
;
3
74 ft.
0.00
Artr
2.24
P
76.70
Arno
15.11
L
13.21
BG
9.36
Eri. spp.
0.73
X
Juos
13.56
Artr
3.30
P
63.50
Arno
7.03
L
BG
Phho
Sihi
Eri. spp.
25.61
10.22
0.12
0.31
0.24
Debris
Check # 3
1
19 ft.
0.00
Arno
8.33
P
L
BG
Eri. spp.
Phho
76.55
13.95
8.34
0.97
0.19
2
Pied
11.63
Artr
4.65
P
41.28
)
33 ft.
Arno
13.76
L
BG
Eri. spp.
Annuals
Chvi
Sihi
52.71
4.67
0.38
O.58
0.19
0.19
Table
JO.
Continued.
•
Transect. /
Number —
Percent
Cover
Plot
Tree
Shrub
2/
Ground —
3
Juos
33.33
Artr
1.76
P
36.47
74 ft.
L
BG
Chvi
38.82
23.93
0.39
Annuals
0.39
X
Juos
11.11
Artr
2.15
P
51.43
Pied
3.88
Arno
7.36
L
BG
Eri.
spp.
35.16
12.52
0.32
Annuals
0.32
Chvi
0.19
Sihi
0.06
Debris
1
Juos
34.78
Artr
6.13
P
37.94
Check # 4
19 ft.
Arno
9.88
L
BG
Phho
Sihi
49.21
11.86
0.79
0.20
2
Juos
24.46
Arno
2.76
P
55.03
33 ft.
L
BG
40.43
4.54
3
Pimo
26.10
Arno
2.39
P
50.80
7^ ft.
L
BG
Sihi
Eri.
spp.
47.01
1.60
0.20
0.39
X
Pied
8.70
Artr
2.04
P
47.92
Juos
19.75
Arno
5.01
L
BG
Phho
Sihy
Eri.
spp.
45.55
6.01
0.26
0.13
0.13
Debris
1
Juos
3.67
Arno
2.32
P
55.21
Check # 5
i
19 ft.
L
BG
Sihi
Phho
27.99
16.02
0.39
0.39
('= ^Table/ft
Continued.
•
Transect 1 ,
Plot Number -
Percent
Cover
Tree
Shrub
2/
Ground —
2
0.00
0.00
P
97.28
33 ft.
L
BG
Astrag.
R
1.16
0.59
spp. 0.19
0.78
3
Juos
16.15
0.00
P
50.96
74 ft.
Pied
14.62
L
BG
Phho
42.31
6.34
0.39
X
Juos
6.61
Arno
0.77
P
67.82
Pied
4.87
L
BG
B
Astrag.
Phho
23.82
7.78
0.26
spp. 0.06
0.26
^d.i.p. # i y i
0.00
Artr
4.67
P
66.54
19 ft.
L
BG
Agcr
Phho
Annuals
Misc.
Eri. spj
28.22
1.51
0.56
2.24
0.56
>. 0.37
2
0.00
Artr
0.68
P
69.56
33 ft.
Arno
0.68
L
BG
Agcr
Phho
Annuals
14.12
13.77
0.51
1.19
0.85
3
0.00
Artr
0.54
P
56.65
74 ft.
L
BG
Agcr
Annuals
36.33
3.42
0.90
2.70
•
Chain with debris in place plots.
m Kable /O.
Continued.
•
Transect, ,
Number -
Percent
Cover
o/
Plot
Tree
Shrub
Ground —'
5
0.00
Artr
1.96
P
64.25
Arno
0.23
L
BG
Phho
Annuals
Misc.
Eri. spp.
26.22
6.23
0.40
1.93
0.19
0.12
D.I. P. # 2
1
19 ft.
0.00
Artr
0.40
P
L
BG
Eri. spp.
R
Agcr
73.19
20.77
5.64
0.20
0.20
2
0.00
0.00
P
59.26
1
33 ft.
L
BG
Eri. spp.
Lupine spp.
Phho
21.40
12.35
0.82
5.97
0.20
3
0.00
0.00
P
56.49
7*+ ft
L
BG
Annuals
Astrag. spp
Agcr
31.38
9.09
0.22
. 2.60
0.22
5
0.00
Artr
0.13
P
L
BG
Eri. spp.
Lupine spp.
Astrag. spp
Phho
Agcr
R
62.98
24.52
9.09
0.27
1.99
. 0.87
0.07
0.14
0.07
D.I.P. # 3
)
1
19 ft.
0.00
Artr
0.96
P
L
BG
Agcr
Annuals
Eri. spp.
58.62
33.72
6.13
0.38
O.96
0.19
m ^Table/^.
Continued.
Plot
•
Transect.. .
Number —
Percent Cover
Tree
Shrub
2/
Ground -
2
Pied
4.21
Artr
0.96
P
65.52
33 ft.
Arno
2.11
L
BG
Lupine spp,
Sihi
Agcr
Misc.
27.01
4.59
1.15
0.77
0.19
0.77
3
Juos
0.57
0.00
P
79.35
74 ft.
L
BG
Eri. spp.
Sihi
Agcr
Annuals
13.96
4.22
0.57
0.19
1.14
0.57
X
Juos
0.19
Artr
0.65
P
67.83
)
Pied
1.40
Arno
0.70
L
BG
Agcr
Annuals
Eri. spp.
Lupine spp.
Sihi
Misc.
?
24.90
4.95
0.57
0.51
0.25
0.38
0.32
0.29
D.I. P.
# 4
1
0.00
0.00
26.97
19 ft.
L
BG
Eri. spp.
Lupine spp.
68.44
2.76
0.18
1.65
2
0.00
0.00
P
21.95
33 ft.
L
BG
Penst. spp.
Misc.
52.57
22.12
2.48
0.88
3
0.00
0.00
P
46.02
74 ft.
L
BG
Annuals
44.55
8.94
0.49
Table
JO.
Continued.
Plot
Transect.. ,
Number —
Percent Cover
Tree
Shrub
Ground -
X
0.00
0.00
P
L
BG
Eri. spp.
Lupine spp.
Penst. spp.
Annuals
Misc.
31.65
55.19
11.27
0.06
0.55
0.83
0.16
0.29
D.I.P.
# 5
1
19 ft.
0.00
0.00
P
L
BG
Agcr
Annuals
30.68
6^.20
h.7k
0.19
0.19
2
0.00
Artr
1.67
P
70.37
>
33 ft.
L
BG
Agcr
Annuals
?
27. 0^+
0.36
0.56
1.67
3
0.00
Arno
2.35
88.81
7^ ft.
L
BG
R
Agcr
Annuals
1.99
8.30
0.36
0.36
0.18
X
0.00
Artr
0.56
P
63.29
Arno
0.78
L
BG
R
Agcr
Annuals
31.08
kM
0.12
0.37
0.68
•
Appendix A
Copy of the manuscript entitled
"Influence of Pinyon- Juniper Conversions and
Water Quality on Permeability of Surface Soils"
Influence of Piny on- Juniper Conversions and Water
Quality on Permeability of Surface Soils 1/
by
Gerald F. Gifford -and Ronald K. Tew &
INTRODUCTION
The influence that various eradication treatments for pinyon- juniper
( pinus fdulis Fngelnu, Pinus monophylla Torr. and Frem. - Juniperus spp. ) have
on water yield, runoff, sediment production, soil moisture patterns, etc., is
of utmost concern to watershed managers in the western United States. The
majority of published papers concerning the hydrology of pinyon- juniper sites
deal with rainfall interception or water yields associated with plant removal.
Pinyon- juniper is generally controlled by chaining (a large anchor chain
is pulled between two tractors to fell the trees), and the debris either left
where it falls or later windrowed. In conjunction with chaining, grass seed
is usually broadcast or drilled, depending on how the debris is handled.
During windrowing, the upper h inches of soil is thoroughly disturbed. Less
disturbance occurs when the debris is left where it falls. It is conceivable,
therefore, that the infiltration and percolation rates of surface soils might
be affected by the debris-disposal treatments.
This study conducted under cooperative agreement between U.S. Forest
Service, Intermountain Forest and Range Experiment Station, and Utah State
University in cooperation with the Bureau of Land Management (Contract 14-11-
0008-2837) .
2/
Assistant Professor, Range Watershed Science and Chairman, Watershed
Science Unit, Utah State University, Logan, Utah 84321.
3/
Presently Associate Professor, Plant Science Dept., Fresno State College,
Fresno, California. Formerly Associate Plant Physiologist, U.S. Forest Service,
Intermountain Forest & Range Experiment Station, Forestry Sciences Laboratory.
Logan, Utah 84321,
' .
•
L
Infiltrometers have been widely used to study the influence of land
management practices on infiltration and erosion. Depending on distance
between sites, natural waters of various qualities may be used to provide
simulated rainfall for infiltration measurements. Final infiltration rates
(governed somewhat by percolation rates) could differ significantly at a given
time and location depending upon source (and, therefore, quality) of water
applied as rainfall.
The objective of this study was to determine the influence that pinyon-
juniper eradication treatments and water quality have on percolation rates of
southern Utah rangeland surface soils disturbed less than one year ago.
METHODS
Two sites were studied, one in southeastern Utah near Blanding and the
other in southwestern Utah near Milford. Pinyon and juniper were the dominant
vegetation types present on both sites. Surface soils varied from a sandy
loam (sandstone-siltstone parent material, 0.2 to 1.1$ rock > 2 mm diameter)
at the Blanding site to a silt loam (basalt parent material, 18.^ to 31.6%
rock > 2 mm diameter) at the Milford site. At each site were the following
treatments: (1) pinyon- juniper chained and windrowed, (2) pinyon- juniper
chained with debris left in place, and (3) undisturbed pinyon- juniper.
Chaining treatments were applied during November, 1967 to a minimum of 30
acres, crested wheatgrass was seeded, and the areas were fenced.
Soil samples were collected during May, 1968 at the 0-2 and 2-k inch
depth intervals at 30 grid points on each 30-acre plot. Samples from three
points were then randomly selected and composited until 10 replications of
composited samples were obtained for each depth interval. The samples were
taken to the laboratory, passed through a 2 mm sieve, and stored until analyzed.
•
•
•
Soil texture was determined by hydrometer method (Bouyoucos, 1962) .
Organic matter content was determined by a wet oxidation method
(Schollenberger, 19^5) • Aggregation, particle density, porosity, and pH were
determined by methods outlined by Richards (195*0. The procedure given by
Reeve (1965) was used for permeability measurements. Only 6 of the 10
replications of the soil samples collected were used for the permeability
measurements.
Three different qualities of water were used for permeability tests on
each soil sample: (1) distilled water, (2) tap water obtained at Milford, and
(3) tap water obtained at Blanding. The quality of the waters (see Table 1)
including pH, conductivity and the content of calcium, magnesium, sodium,
potassium, carbonate, bicarbonate, chloride and sulfate was determined by
methods of analysis given by Richards (195*1-) •
The soils were prepared for permeability studies by dumping each sample
into a 3-ounce can which had a wire screen and a filter paper covering the
bottom. Each can had a small hole punched in the bottom for drainage and a
cylinder extension placed at the top. The soil was packed by dropping the
container from a height of 2.5 cm 200 times on a wooden block. The cylinder
extension was removed and the soil leveled to the top of the can. The same
packing procedure was used to obtain bulk density values used in porosity
calculations. After the soils were leveled in the cans, the cylinder extension
was replaced and sealed to the can with rubber cement. The sample was then
placed on a rack where water was admitted to the sample from a supply tank
having a constant head. The quantity of water percolating through the soil
was measured at 5-minute intervals for a total of k^> minutes.
Soil permeability was calculated using the equation and symbols given by
Reeve (1965) where:
k = _N_ VL
P g A & h a t
w
•
Table 1. Quality of waters used for percolation study (excluding distilled
water.
Quality
Measured
Source of Water
Bl an ding Mil ford
ECX
: lcr
PH
Ca
(ppm)
Mg
(ppm)
Na
(ppm)
K
(ppm)
C0 7
HOC
) (ppm)
50 k
(ppm)
CI
(ppm)
18
8.15
25
5
h
0.8
none
176.3
11.0
0.50
^5
8.36
Ik
k.8
63
3.2
none
10^.6
37.^
35.5
•
#
in which:
•
2
k = intrinsic permeability with water, cm
N = water viscosity, poises
3
P s water density, g/cm
2
g = acceleration of gravity, cm/sec
V s volume of percolate in time t, cm
L = length of soil column, cm
.:\h a difference in hydraulic head between inflow and outflow, cm
2
A = cross sectional area of soil column, cm
/\t = time interval involved, sec.
RESULTS
Analysis of variance of intrinsic permeabilities after k$ minutes and
also volume of water percolated through the soil columns after each 5-minute
interval revealed significant interactions among site x treatment, site x depth,
and treatment x soil depth. Quality of water did not significantly affect
percolation rates the first half hour, but was a significant factor thereafter.
At the Milford site, treatment significantly influenced intrinsic
permeability of the soil columns (Table 2). Pooled over both depths and three
waters, mean intrinsic permeability of surface soils from the chain and windrow
2 2 2
treatment was 1.13 cm compared with 0.34 cm and 0.5^ cm for chaining with
debris in place and control treatments, respectively. The trend was the same
at the Blanding site but differences among treatments were not significant
at the .05 level of probability.
In addition, at the Milford site, intrinsic permeability values of soil
samples from the 2-k inch depth were significantly greater than those from
the 0-2 inch depth (Table 3). Pooled over three treatments and three waters,
•
k
Table 2. Influence of pinyon- juniper treatment on intrinsic permeability
(cm ) of soil columns after 45 minutes (two sites).
Site
Bl an ding
Mil ford
Treatment —
Chain , windrow
1.00 c
1.13
Chain, debris
in place
o.8o a
0.84 a
Control
0.76 s
0.54 £
1/
Any two means in same row with same letter are not significantly different
at .05 level of probability (Duncan's multiple range test). Means
represent two depths, three waters, and six replications.
Table 3. Influence of depth from which soil sample was collected on
intrinsic permeability (cm 2 ) after k5 minutes (two sites).
Soil depth (inches) —
Site 0-2 2-4
Blanding 0.71 a 1.00 &
Milford 0.^0 a 1.28 b
- Any two means in same row with same letter are not significantly
different at .05 level of probability (Duncan's multiple range test).
Means represent three treatments, three waters, and six replications,
mean intrinsic permeability was 3.2 times greater in soil from the 2-4 inch
depth than in soil from the 0-2 inch depth. For soil from the Blanding site,
mean intrinsic permeability was 1.4 times greater at the 2-4 inch depth than
at the 0-2 inch depth. Differences at the Blanding site were not significant.
The chain and windrow treatment significantly influenced intrinsic
permeability at the 2-4 inch depth (Table 4) . There were no significant
differences between control and chaining with debris in place at the 2-4 inch
depth, nor were there significant differences among any treatments with respect
to intrinsic permeability of soil from the 0-2 inch depth. The trend, however,
was toward increased permeability with the chain and windrow treatment.
As mentioned above, water quality influenced volume of percolate only
after 30 minutes. Since intrinsic permeabilities were calculated after 45
minutes, water quality was a significant factor. Pooled over two sites, three
treatments, and two soil depths, mean intrinsic permeability for distilled
2 2
water was O.78 cm , for Milford water 0.88 cm , and for Blanding water 0.87
2
cm . Intrinsic permeabilities for Milford and Blanding waters were not
significantly different at the .05 level of probability.
Factors Influencing Permeabilities
Parameters associated with each soil column were measured to determine
their influence on percolation rates and intrinsic permeabilities for each of
the three waters. The parameters included soil texture (sand, silt, clay,
silt plus clay, % rock > 2 mm diameter originally in sample), % aggregation,
% organic matter, pH, bulk density, particle density, and % total porosity.
Soil factors important for predicting percolated volumes after each 5-minute
interval did not change significantly with time, so only factors important in
predicting intrinsic permeabilities after 45 minutes are considered here.
Three multiple regression equations were derived for predicting intrinsic
Table k. Influence of pinyon- juniper treatment on intrinsic permeability
(cm ) after V? minutes (two soil depths).
Treatment -
Depth Chain, debris
(inches) Chain, windrow in place Control
0-2 0.72 9 " 0.50 a 0.^ a
2-4 l.^l 13 l.l^ a 0.87 a
•
1/
- Any two means in same row with same letter are not signifxcantly
different at .05 level of probability (Duncan's multiple range test).
Means represent two sites, three waters, and six replications.
•
i
•
p
permeabilities (k , cm ) after 45 minutes at either the 0-2 or 2-4 inch soil
w
depth at either site, one equation for each of the three waters:
Distilled water
Y = -2.65^ - .087 (.% organic matter) + .090 (% total porosity)
- .011 {% silt plus clay) R 2 = O.56 (R = .75)
Mil ford water
Y - -15.362 + 3.796 (bulk density, g/cc) + .026 (% sand) +
.195 (% total porosity) + .04l (% clay) R 2 = 0.65 (R ■ .81)
Blanding water
Y = -8.527 + 4.986 (particle density, g/cc) + .027 (% sand)
-3.893 (bulk density, g/cc) + .037 (% clay) R 2 = 0.64 (R = .80)
It is obvious that the optimum equation for each water contains factors which
differ from the other two. Percent total porosity explained 45 and 58% of the
variation associated with intrinsic permeabilities measured with distilled
and Milford waters, respectively. The remaining variables explained from one
to six percent of the variation. With Blanding water, bulk density explained
45% of the variation associated with intrinsic permeabilities while the
remaining variables explained from 1 to 12% of the variation.
DISCUSSION
Permeability of surface soils on pinyon- juniper sites is an important
hydrologic variable. This factor is particularly important on sites where
soil surface protective cover (canopy cover, litter, erosion pavement) is
sufficient to allow potentially high infiltration rates. Vegetative
manipulation treatments which enhance surface soil permeability, and at the
same time maintain or increase protective soil cover, should be encouraged
where economically (or otherwise) feasible.
•
Results of this study indicate that chaining of pinyon- juniper does
increase permeability of the 0-2 and 2-4 inch surface soil depths during the
first year following treatment. The chaining with windrowing treatment was
particularly effective in this respect. Mechanical soil disturbance
associated with this treatment probably increases noncapillary porosity
through decreased bulk densities and incorporation of litter into the surface
soils. Such relationships are shown in Figure 1 for the Milford (Basin and
Range Province) site.
Permeability of soil from the 0-2 inch depth was less than that from the
2-k inch depth, regardless of treatment. A greater aggregation percentage in
the 2-h inch depth, especially at the Milford site, may partially account for
the observed differences.
Percolation rates were not influenced by the qualities of water in this
study during the first 30 minutes of each percolation trial. Therefore, to
the extent that percolation governs infiltration, no bias resulting from water
quality should arise if infiltrometer runs on these sites are held to 30 minutes
or less.
Effect of percolation on infiltration rates at these sites should increase
as seeded species become established. During the time when chained and
windrowed pinyon- juniper sites lack soil protective cover, surface conditions
such as raindrop compaction and aggregate breakdown plus clogging of soil pores
will result in increased overland flow and greater sediment production than
control (or undisturbed) areas which still support some protective vegetative
canopy (Gifford, unpublished data). In other words, increased soil permeability
is no asset if water is unable to enter the soil surface.
Regression equations for predicting intrinsic permeability of soil columns
varied according to the quality of water. This type of variation may influence
regression equations used for predicting infiltration rates on semiarid range-
land sites, especially if various qualities of water are used during infiltration
measurements.
20'
,A
ft
u
^
fc
u
3
0-
"""""v^
10
.
u
s
2-4 0-2
SOIL DEPTH , INCHES
•
Figure 1. Characteristics of soils under three pinyon-juniper eradication
treatments at the Milford, Utah site. Dotted line represents
untreated; broken line represents chaining with debris in place;
solid line represents chain and windrow treatment.
REFERENCES
Bouyoucos, G. J., Hydrometer method for making particle size analysis
of soils, Agron. J., 3k, k&k-k65, 1962.
Reeve, R. C, Air-to-water permeability ratio, In Methods of soil analysis,
I., Amer. Soc. Agron., Madison, Wisconsin, 19 65.
Richards, L. A., Diagnosis and improvement of saline and alkali soils,
U. S. Dept. Agr. Handbook No. 60, Washington, D. C, 195^.
Schollenberger, C. J., Determination of soil organic matter, Soil Sci.,
59, 53-56, 19^5-
*
•
#
^r
•
Abstract. Permeability of surface soils from the 0-2 and 2-k inch
depths at each of two sites in the pinyon- juniper type of southeastern and
southwestern Utah were studied using disturbed soil samples. Three recent
vegetation manipulation practices (chaining and windrowing, double chaining
with debris left in place, and undisturbed) and three qualities of water
^ dre studied in this respect. The chaining with windrowing treatment
significantly increased permeability of surface soils from southwestern Utah.
Significant differences in permeability were lacking between soils from
double chaining with debris in place and undisturbed treatments. Permeability
of surface soils from southeastern Utah provided a similar trend, though
significant differences among treatments were not evident.
Water quality influenced percolation only after approximately 30
minutes. Multiple regression equations developed for predicting intrinsic
permeabilities varied according to quality of water.
#
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£>.
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•
#
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