CONSERVATION TILLAGE EFFECTS ON INFILTRATION AND IRRIGATION
ADVANCE TIMES IN ARIZONA COTTON
E.C. Martin, K.O. Adu-Tutu, W.B. McCloskey, S.H. Husman, P. Clay and M. Ottman
University of Arizona, Tucson, AZ
Abstract
Field experiments were initiated in 2001 for a cotton-based conservation tillage
project at sites in Marana, Coolidge, and Goodyear, Arizona. For the 2002
season, soil and water management assessments were made to evaluate surface
irrigation performance under conservation tillage, following cover and grain
crops. An additional site was added in the winter of 2002 at Maricopa, Arizona.
Analyses included soil texture, infiltration rate, and water advancement. At
Coolidge, conservation tillage plots had higher infiltration rates and longer
advance times than the conventional plots in 2002 and 2003. At Marana,
infiltration rates were initially higher for the Conservation plots but the rates
converged at the end of four hours in 2002. In 2003, Conventional plots
infiltrated about one inch more. Advance times for Marana showed water
infiltration for Conventional wheel rows to be the fastest. At Goodyear,
Conservation plots infiltrated more than Conventional plots during 2002. This
also resulted in a slower advance time for the Conservation plots. In 2003,
treatment effects were not comparable due to tillage by the grower. At
Maricopa, Conservation plots infiltrated almost 2.2 inches more water than
Conventional plots and water reached the end of the field three hours ahead of
the fastest Conservation plot. Seasonal irrigation water applications to each
treatment were relatively equal for all sites with the exception of Coolidge.
Here, the long field combined with sandy soil made it difficult to adequately
irrigate the Conservation plots. In 2002, an additional 21 inches of water was
applied to the Conservation plots. In 2003, that amount was reduced to 12.5
inches. The yield data show a significant difference in 2002 only at Coolidge.
There, Conservation plots yielded more than the Conventional ones. This may
have been due to more water applied to the Conservation plots. In 2003, the
opposite occurred with the Conventional plots yielding more than the
Conservation plots. This could have been due to herbicide damage. At
Maricopa, the Conventional plot also yielded more than the Conservation plot.
Initial indications are that the conservation tillage does impact irrigation
performance and may not be suitable for all locations depending on soil type
and field layout.
Introduction
Conventional cotton production practices in Arizona typically involve several tillage operations, including
land-planing, leveling, several disking operations, chisel plowing, and cultivation for weed control and
maintenance of irrigation furrows. A law for pink bollworm control requires some tillage after the cotton
season, although recent regulatory changes have allowed a reduction in tillage. Tillage operations may
lead to degradation of soil structure, oxidation of organic matter and soil loss through wind and water
erosion.
Conservation tillage is an alternative production system that offers numerous economic and
environmental benefits. Over time, crop residue on the soil surface may increase the infiltration of water
into the soil by 25-50%, reduce crusting and decrease the effect of wind and temperature on soil water
Arizona Cotton Report (P-138) May 2004
25
evaporation from the soil surface relative to conventional tillage production (Baumhardt and Lascano,
1999; Daniel et al., 1999). Reducing tillage operations can also enhance cotton root growth by
minimizing soil compaction. Raper et al. (1998) reported that the greatest cotton root growth, greatest
depth to hardpan, and least amount of compaction occurred in a wheat – cotton, double-crop study when
subsoiling was done in combination with no-till cotton planting into the grain stubble with no tillage
during the cotton season.
These beneficial effects of conservation tillage practices related to soil and water management can
enhance environmental quality and improve the natural resource base on which a large portion of
Arizona’s agricultural economy depends. Thus, a cotton-centered conservation tillage project was started
in the fall of 2001 with the planting of cover and grain crops. The objective of the soil and water
management component of the project was to evaluate the effects of the conservation tillage on irrigation
management over at least a 3-year period.
Materials and Methods
Soil and water management assessments were made in 2002 in conservation tillage field experiments
already established on two commercial farms located in Coolidge and Goodyear, Arizona, along with a
site at the University of Arizona’s Marana Agricultural Center, Marana, Arizona. In the conservation
tillage plots, small grains were used as cover crops during the winter. For early planting, the small grain
was chemically killed and the cotton was planted directly into the cover crop residues using a John Deere
MaxEmerge II planter equipped with Yetter Farm Equipment 2976 residue manager/coulter assemblies.
For the late planting, the small grain was harvested and the cotton was planted directly into the stubble
with the same planter setup
Treatments
2002 Season
At the Coolidge site, the tillage/cover crop treatments were: (1) conventional tillage/winter fallow
followed by conventional cotton; (2) conservation tillage/Solum barley cover crop followed by no-till
cotton planting; and (3) conservation tillage/oat cover crop, followed by no-till cotton planting. For this
analysis, only treatment 1 (conventional) and treatment 2 (conservation) were measured.
Treatments at Goodyear were: (1) fall conservation tillage/Poco barley grain crop, spring no-till cotton
planting; and (2) fall conservation tillage/Poco barley grain crop, spring conservation tillage cotton
planting. Treatment 1 was considered the conservation treatment and treatment 2 was the conventional.
Treatments at Marana were: (1) conventional tillage/winter fallow, conventional cotton planting in April
(early planting); (2) conservation tillage/no-till barley cover crop, no-till cotton planting (early planting);
(3) conventional tillage/winter fallow, conventional cotton planting in late May/early June (late planting);
and (4) conservation tillage/no-till Solum barley grain crop, no-till cotton planting (late planting).
Treatment 1 (conventional) and treatment 2 (conservation) were analyzed at the Marana site.
2003 Season
In 2003, the treatments remained relatively the same with only a few alterations. At the Coolidge site,
treatment 1 and treatment 3 remained the same as in 2002. Treatment two was changed to conventional
tillage/winter fallow followed by conventional cotton using Telone® and treatment 4 was dropped. For
this analysis, only treatment 1 (conventional) and treatment 3 (conservation) were measured.
Arizona Cotton Report (P-138) May 2004
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At the Goodyear and Marana sites, the treatments were the same as in 2002. However, at the Goodyear
site, due to problems of water ponding at the tail end of the field, the entire field was disked and releveled, thus impacting all treatments. Measurements were still taken according to the treatments that
were imposed in the fall 2003.
An additional site was added to the experiment in 2003 at the University of Arizona’s Maricopa
Agricultural Center (MAC). The treatments at MAC were: (1) conventional cotton planting in April
(early plant); (2) conservation tillage/no-till Solum barley cover crop, no-till early cotton (early planting);
(3) conventional tillage/winter fallow, conventional cotton planting in late May/early June (late planting);
and (4) conservation tillage/no-till Solum barley grain crop, no-till late cotton (late planting). Treatment 1
(conventional) and treatment 2 (conservation) were analyzed at the Maricopa site.
Measurements
The impact of conservation tillage on irrigation performance was assessed by analyzing infiltration rates
and irrigation water advance times. At Coolidge, Marana and Maricopa, where crops were planted on
beds and furrow-irrigated, blocked furrow infiltrometers similar to those of Walker and Skogerboe (1987)
were used to measure infiltration. These infiltrometers consisted of two pieces of stainless steel metal cut
to the geometry of a furrow. The metal was pounded into the soil, three feet apart. The furrows on either
side of the furrow being measured were also blocked off (using soil dams) and irrigated at the same time,
as was the measured furrow outside of the metal sheets. This was done to minimize horizontal water
movement and simulate, as best as possible, measurements being taken during an irrigation event. Water
was then poured into the dam created by the two pieces of metal and the water depth measured (see
Figure 1). As the water infiltrated into the soil, more was added. Water depth measurements were taken
every 30 seconds for the first two minutes, then every minute for the next three minutes. Then,
measurements were taken every five minutes for the remainder of the first hour. Additional
measurements were then taken every ten minutes for the second hour, every 20 minutes for the third hour
and then every 30 minutes for the fourth and final hour. When water was added into the dam, the time
and amount was noted. After all the water had infiltrated into the soil, measurements of the furrow
geometry were made and used to calculate the infiltration rate. Throughout the entire measurement
period, the water depth within the infiltrometer as well as the area surrounding the measurement zone was
kept at a constant depth 3 cm. This was done to assure that the water level did not exceed the height of
the bed and simulate a normal irrigation event. All infiltration measurements were made in non-wheel
rows.
At Goodyear, where crops were planted in level basins and flood-irrigated, a modified ring infiltrometer
was used similar to that described by Haise et al. (1956). The inner ring, within which the measurements
were made, was a piece of well casing 12 inches in diameter. The outer ring was constructed from the
soil nearby. The outer ring formed a mote and was filled with water and was maintained at a depth that
simulated an irrigation event. The inner ring was filled with water and, water additions and measurement
were recorded and the water level maintained as previously describe with the furrow infiltrometers.
The advance times for the treatments at various sites were recorded a few days after infiltration data were
collected. Flags were placed every 100 ft down the row and the time the water reached each flag was
recorded as the water advanced down the field. For the Marana and Coolidge sites, six plots (three
conventional and three conservation) were observed in 2002. At the Goodyear site, only one treatment of
each was observed. This was due to the irrigation timing (occurring at night) and the change in the
irrigation set times during the irrigation event. In 2003, six plots (three conventional and three
conservation) were measured at all sites.
Arizona Cotton Report (P-138) May 2004
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Field slope was also determined for the plots where the infiltration and advance time data were collected.
The slope data were taken by setting up a survey transit in the center of the plot and then measuring 300 ft
up and 300 ft down the field. These measurements gave a rough estimate of the overall field slope.
In addition to the soil water and field slope parameters measured, an attempt was made to characterize the
texture of the soil at each site. Soil samples were taken every 6 inches down to a depth of 30 inches.
Using the hydrometer or Bouyoucos method (Bouyoucos, 1936) an analysis of percent sand, silt and clay
was performed to determine the soil type.
Results and Discussion
Soil Texture
The Coolidge site contained the greatest amount of sand of the four sites (Figure 2). Although there was
some variation between depths at Coolidge, overall, the percentages of the particle size categories stayed
fairly constant with clay slightly increasing with depth while sand slightly decreased. Overall, the soil
would be classified as a sandy clay loam.
With clay content above 40% in the top two feet of the soil profile, the soil at the Marana site contained
the greatest percentage of clay among the experimental sites (Figure 3). The sand and silt contents varied
slightly with depth and there was a relatively large change at the 2-ft depth. Soil classifications for each
layer ranged from clay to sandy clay but overall the soil at Marana is classified as clay soil.
The Goodyear site had greater than 50% silt content throughout the upper 30 inches of the soil profile
(Figure 4). The clay content was greater in the top two feet and then decreased to almost equal the
percentage of sand at the 30-inch depth. The soil types ranged from silty clay loam to silty clay to silt
loam, but overall, the Goodyear soil would be classified as a silty clay loam.
Clay dominated the top 18 inches of the soil at the Maricopa site (Figure 5). At 24 inches, the sand
content increased almost 20% and was at 60% at the 30-inch depth. Soil types ranged from clay loam in
the top 18 inches to sandy clay loam in the 18-30 inch depths. Overall, the soil type would be classified
as a clay loam.
Infiltration
Conservation tillage practices would be expected to increase infiltration by leaving old root channels
intact, allowing the water to flow deeper through the soil vadose. Also, surface organic residues usually
slow the advance of the water front resulting in increased opportunity time for infiltration. However, in
many situations in surface irrigation, increased infiltration may actually hinder the movement of water
down the field, resulting in excessive water application and reducing irrigation efficiency. At all of the
sites, soil samples were taken prior to infiltration measurements to determine if any difference existed in
soil moisture in the top 30 inches. None of the sites showed any differences at the time of the
infiltration/advance time measurements (data not shown).
Arizona Cotton Report (P-138) May 2004
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2002 SEASON
Infiltration measurements were performed at the Coolidge site on May 22, 2002. Due to the high sand
content in the soil at that site, the infiltration was relatively high with 10 and 7 inches of water infiltrating
the soil in a four hour period in the conservation and conventional treatments, respectively (Figure 6).
The soil at the Marana site contained a much higher concentration of clay than the Coolidge site.
Infiltration measurements were done on June 4 – 5, 2002. Although the water in the conservation plots
had a higher initial infiltration rate, at the end of the four hour measurement period, an average of four
inches of water had infiltrated into both the conventional and conservation plots (Figure 7). The soil at
the Goodyear site was silty, and the soil was relatively moist at the time of assessment. Infiltration data
were recorded on June 20 – 21, 2002. Within the four hour infiltration period, an average of 1.5 inches of
water infiltrated the conservation treatment while one inch of water infiltrated the conventional treatment
(Figure 8). These results indicate that on coarse textured soils, conservation tillage practices did appear to
increase infiltration as expected. In the finer textured soil at Marana, there was initially a faster
infiltration rate but the total amount of water infiltrated was equal at the end of the four hour measurement
period.
2003 Season
Infiltration measurements were conducted at the Coolidge site on May 15, 2003. The results were similar
to 2002 with the conservation plots having a much greater infiltration rate (Figure 9). Similar to the 2002
data, the conservation plots averaged just over 10 inches of water infiltrated in a four hour period. The
conventional plots infiltrated just over four inches in the same time period. This was actually three inches
less than in 2002. The Marana data from 2003 showed that the conventional plots actually infiltrated
more water than the conservation plots (Figure 10). The difference was less than one inch over the four
hour measurement period. At the Goodyear site, infiltration data were taken but the treatments for all
plots were considered the same since deep ripping and land leveling took place during the spring of 2003
(Figure 11). As in 2002, the amount of water infiltrated was well below the other sites. The MAC site
was added in the fall of 2002 and the infiltration data are shown in Figure 12. The conservation plots
infiltrated more water than the conventional plots. For the MAC site, the difference was 2.4 inches during
the four hour measurement period.
Advance Times and Field Slope
2002 Season
The Coolidge site had a fairly shallow field slope measuring 0.06%. Advance time measurements (June
3-5, 2002) showed the irrigation water reached the end of the conventional plots in about one hour but
had not reach the end of the conservation plots after 8.5 hr, at which point measurements were suspended
due to darkness (Figure 13). Both wheel and non-wheel rows were to be measured but due to breaks in the
beds where the water would cross over into the adjoining row, the conservation non-wheel row was
stopped at 900 ft and the conventional wheel row was dropped from the data set. The grower’s set times
for irrigating the conventional and conservation plots for the 2002 season were 6 and 12 hrs, respectively.
The Marana field had a slightly greater slope of 0.08%. The advance times recorded on June 6, 2002, for
both wheel and non-wheel rows are shown in Figure 14. Water in the wheel rows for both treatments
advanced faster down the field than water in the non-wheel rows. However, water in the conservation
non-wheel row advanced faster than water in the conventional non-wheel row.
Arizona Cotton Report (P-138) May 2004
29
The Goodyear site had the greatest measured slope of the three sites. Measurements indicated that plots
had a field slope of 0.12%. Advance times measured on June 22, 2002, for the two treatments are shown
in Figure 15. At the beginning of the irrigation, water in both treatments seemed to be advancing at the
same rate. However, by the end of the measurement period, the advance times differed by about one
hour. Measurements were suspended at 1000 ft from the ditch because water was backing up within the
plot, making it impossible to determine advance times. In fact, for the conventional plots, in-field
borders, running perpendicular to the water flow were constructed along both sides to slow the
advancement and help to more evenly distribute the water.
2003 Season
The Coolidge plots measured in 2003 were similar but not the same plots as in 2002. Due to problems
with plot size and the irrigation water supply ditch, the research plots were moved west. This meant that
Rep 2 became, Rep 1, Rep 3 became Rep 2, etc. In 2002, Reps 1, 2 and 3 were measured. In 2003, Reps
2, 3 and 4 were measured. The average slope for the plots in 2003 was 0.04%, slightly lower than in
2003. Advance time measurements were difficult to obtain due to continuous break-overs into adjacent
rows (Figure 16). Only the conventional wheel row was recorded to the end of the field. However, some
data were collected for both treatments in both the wheel and non-wheel rows that allowed some
comparisons. For example, at the 800 ft distance, the water in the conventional-wheel row arrived in just
over one hour while water in the conservative wheel row took almost 3.5 hours to reach the same
distance. Also, the advance times for the conservation and conventional non-wheel rows were virtually
the same until the 400 ft mark when the water began breaking into adjacent rows.
The Marana data for 2003 is shown in Figure 17. Elevation data showed the fields to average about
0.05% slope, slightly lower than the 0.08% measured in 2002. The advance time results were similar to
2002 with the water in the conventional wheel row having the fastest advance time. However, unlike
2002, the conventional non-wheel row had the slowest advance times. These data support the theory that
perhaps the soil’s natural cracking abilities may be compensating for the increased infiltration cause by
the conservation tillage effects. In the conventional plots, the bare soil has tendency to form large, deep
cracks in the soil. As the advancing water reaches these cracks, the water must first fill the cracks before
continuing down the row. In the conservation plots, the advancement of the water is often hindered by
the surface residue. These two characteristics, the cracks and the surface trash, seem to have similar
effects on water advancement.
In Goodyear, data were recorded on four plots (Figure 18). Although all of these plots were deep ripped
and replaned, there were still some inherent spatial differences in slope. The plots measured averaged
0.06% slope, ranging from 0.04-0.08%. The advance times shown in Figure 18 reflect this with the slope
of plot 3 and 4 measuring 0.04%, the slope of plot 5 measuring 0.06% and the slope of plot 6 measuring
0.08%.
At the Maricopa site, the data showed the fields actually increasing in elevation towards the end of the
field. This was due to the quick rise that occurred at the 600 ft mark (the end of the field). This was done
at the farm to assure the water doesn’t leave the field and spill into the adjoining road. Once the 600 ft
reading was removed, the field had a slope of 0.00007%, basically level. The advance times recorded
(Figure 19) followed a somewhat expected pattern with the water in conventional wheel rows advancing
the fastest, followed by the water in the conventional non-wheel row, the water in the conservation wheel
row and lastly the water in the conservation non-wheel row.
Arizona Cotton Report (P-138) May 2004
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Irrigation Water Applied
A summary of the irrigation water applied to the cotton crops in the 2002 and 2003 season is shown in
Table 1. In 2002 and 2003, at the Coolidge and Marana sites, conservation tillage plots received more
water than the conventional plots. At Goodyear, both tillage systems received the same amount of water.
Thus, as expected, conservation tillage practices increased irrigation advance times and the amount of
water applied to the cotton crop at Coolidge and Marana but the greater field slope at Goodyear appeared
to minimize the effect of tillage practices on irrigation water advance times and the amount of water
applied. At Coolidge, the low slope, low irrigation water supply flow rate and sandy soil led to excessive
water application. The long set time meant inefficient irrigation, causing an additional 21 inches of water
to be applied to the conservation plots in 2002, and 12.6 inches more in 2003. At Marana, with a high
clay content soil, the additional water applied was only in the beginning of the season. In both years, the
additional water was applied due to the difference between pre-irrigating the conventional plots as
opposed to irrigating up the conservation plots. At Goodyear, the presence of surface trash on the no-till
plots helped to slow down the water front, an effect similar to the construction of in-field borders on the
conventional plots.
Yield Data
The yield data for the 2002 and 2003 seasons are given in Table 1. In 2002, only the Coolidge site
showed a significant difference in yield. This may be more due to the additional 21 inches of water
applied to the conservation plots rather than the effects of the management itself. In the 2003 season
(Table 1), the Coolidge site again showed a significant difference in yield but in the reverse order, i.e., the
conventional yielded higher than the conservation. This may been due to herbicide damage that was
observed. At the Maricopa site, yields were relatively low compared to data from other fields on the farm
and the cause of the yield difference it not yet know.
Summary
It is difficult to assess the effects of tillage management in 1-2 years. However, it can clearly be seen that
conservation tillage will in fact slow water advancement and in some cases, significantly increase
infiltration. In many agronomic scenarios, this would be a benefit. However, in large-scale surface
irrigation, the reduction of the advancement down the row may actually reduce irrigation efficiency.
References
Baumhardt, R.L. and R.J. Lascano. 1999. Water budget and yield of dryland cotton intercropped with
terminated winter wheat. Agron. J. 91:922-927.
Bouyoucos, G. J. 1936. Directions for Making Mechanical Analysis of Soils by the Hydrometer Method.
Soil Sci. 42(3).
Daniel, J.B., A.O. Abaye, M.M. Alley, C.W. Adcock, and J.C. Maithland. 1999. Winter annual cover
crops in a Virginia no-till cotton production system: II. Cover crop and tillage effects on soil moisture,
cotton yield, and cotton quality. J. Cotton Sci. 3:84-91.
Haise, H.R., Donnan, W.W., Phelan, J.T., Lawhon, L.F., and Shockley, D.G. 1956. The use of cylinder
infiltrometers to determine the intake characteristics of irrigated soils. Publ. ARS 41-7, Agricultural
Research Service and Soil Conservation Service, USDA, Washington DC.
Arizona Cotton Report (P-138) May 2004
31
Raper, R.L., D.W. Reeves, and E.C. Burt. 1998. Using in-row subsoiling to minimize soil compaction
caused by traffic. J. Cotton Sci. 2:130-135.
Walker, W.R. and Skogerboe, G.V. 1987. Surface Irrigation: Theory and Practice. Prentice-Hall,
Englewood Cliffs, New Jersey. 386p.
Arizona Cotton Report (P-138) May 2004
32
Table 1. Irrigation water applied for the 2002 and 2003 cotton seasons.
Location
Season
Irrigation water added (in.)
2002
Conventional
Conservation
Coolidge
55.5
76
Marana
37
39
Goodyear
67
67
2003
Coolidge
50
62.6
Marana
53
58
Goodyear
NA
NA
Maricopa
55.5
55.5
NA = not available
Table 2. Yield data for the 2002 and 2003 cotton seasons.
Location
Season
Lint Yield (lbs/ac)*
2002
Conventional
Conservation
Coolidge
702a
869b
Marana
910a
869a
Goodyear
729a
751a
2003
Coolidge
1230a
941b
Marana
901a
755a
Goodyear
485a
531a
Maricopa
910a
763b
*Values are means of 4 replications; means in a row followed by the same letter are not different at
P=0.05 according to the Student-Newman-Keuls significant difference test.
Arizona Cotton Report (P-138) May 2004
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A
D
B
C
Figure 1. Details of the infiltration measurement. Starting at the top, clockwise: A) The dams are
pounded into place and a plastic sheet is set inside. Water is added and measurements begin when the
plastic sheet is removed; B) The water around the infiltrometer is also kept at a level to mimic an
irrigation event; C) Water level measurements are taken to determine the amount of water infiltrated; D)
Detail of the water level measurement.
Arizona Cotton Report (P-138) May 2004
34
80
Sand
70
Silt
Clay
Soil Particle (%)
60
50
40
30
20
10
0
6
12
18
24
30
Soil Depth (inches)
Figure 2. The average sand, silt and clay content in the sandy clay loam soil at depths of 6 to 30 inches at
the Coolidge conservation tillage experiment.
60
Sand
Soil Particle (%)
50
Silt
Clay
40
30
20
10
0
6
12
18
24
30
Soil Depth (inches)
Figure 3. The average sand, silt and clay content in the clay soil at depths of 6 to 30 inches at the Marana
site conservation tillage experiment.
Arizona Cotton Report (P-138) May 2004
35
70
Sand
Soil Particle (%)
60
Silt
Clay
50
40
30
20
10
0
6
12
18
24
30
Soil Depth (inches)
Figure 4. The average sand, silt and clay content at depth of 6 to 30 inches in the silty clay loam soil at
the Goodyear site.
70
%Sand
Soil Particle (%)
60
%Silt
%Clay
50
40
30
20
10
0
6
12
18
Soil Depth (inches)
24
30
Figure 5. The average sand, silt and clay content at depth of 6 to 30 inches in the silty clay loam soil at
the Maricopa site.
Arizona Cotton Report (P-138) May 2004
36
12
Depth Infiltrated (inches)
10
8
6
4
Conventional
2
Conservation
0
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
Time (hr)
Figure 6. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Coolidge in May 2002.
4.5
Depth Infiltrated (inches)
4
3.5
3
2.5
2
1.5
Conventional
1
Conservation
0.5
0
0
0.5
1
1.5
2
2.5
Time (hr)
3
3.5
4
4.5
Figure 7. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Marana in June 2002.
Arizona Cotton Report (P-138) May 2004
37
1.6
Depth Infiltrated (inches)
1.4
1.2
1
0.8
0.6
Conventional
0.4
Conservation
0.2
0
0.00
0.50
1.00
1.50
2.00
2.50
Time (hr)
3.00
3.50
4.00
4.50
Figure 8. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Goodyear in June 2002.
12
Conventional
Depth Infiltrated (inches)
10
Conservation
8
6
4
2
0
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
Time (hr)
Figure 9. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Coolidge in May 2003.
Arizona Cotton Report (P-138) May 2004
38
7
Depth Infiltrated (inches)
6
5
4
3
2
Conventional 2003
1
Conservation 2003
0
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
Time (hr)
Figure 10. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Marana in June 2003.
0.4
Depth Infiltrated (inches)
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
0.00
0.50
1.00
1.50
2.00
2.50
Time (hr)
3.00
3.50
4.00
4.50
Figure 11. Average depth of water infiltrated in the conventional and conservation tillage treatments at
Goodyear in June 2003.
Arizona Cotton Report (P-138) May 2004
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6
Conventional
Depth Infiltrated (inches)
5
Conservation
4
3
2
1
0
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
Time (hr)
Figure 12. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Maricopa in June 2003.
8:24
C onv - W
C ons - W
C ons - N W
Elapsed Time (hr)
7:12
6:00
4:48
3:36
2:24
1:12
0:00
100
200
300
400
500
600
700
800
900 1000 1100 1200
Distance from Head E nd (ft)
Figure 13. Average irrigation advance times in the conventional (Conv) and conservation (Cons) tillage
treatments for the wheel rows (W) and non-wheel (NW) rows at Coolidge, Arizona, May 2002.
Arizona Cotton Report (P-138) May 2004
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Elapsed Time (hr)
8:24
7:12
Conv - W
Conv NW
6:00
Cons - W
Cons - NW
4:48
3:36
2:24
1:12
0:00
100
200
300
400
500
600
Distance for Head End (ft)
Figure 14. Average irrigation advance times in conventional (Conv) and conservation (Cons) tillage
treatments for the wheel rows (W) and non-wheel (NW) rows at Marana, Arizona, June 2002.
4:19
3:50
Conv
Elapsed Time (hr)
3:21
Cons
2:52
2:24
1:55
1:26
0:57
0:28
0:00
100
200
300
400
500
600
700
800
900
1000
1100
Distance from Head End (ft)
Figure 15. Average irrigation advance times in the conventional (Conv) and conservation (Cons) tillage
treatments at Goodyear, Arizona, June 2002.
Arizona Cotton Report (P-138) May 2004
41
6:00
Elapsed Time(hr)
4:48
Conv- W
Conv- NW
Cons - W
Cons - NW
3:36
2:24
1:12
0:00
100
200
300
400
500
600
700
800
900
100 1100 1200 1300
Distance from Head End (ft)
Figure 16. Average irrigation advance times in conventional (Conv) and conservation (Cons) tillage
treatments for the wheel rows (W) and non-wheel (NW) rows at Coolidge, Arizona, May 2003.
7:12
Elapsed Time(hr)
6:00
4:48
Conv - W
Conv - NW
Cons - W
Cons - NW
3:36
2:24
1:12
0:00
100
200
300
400
500
600
Distance from Head End (ft)
Figure 17. Average irrigation advance times in conventional (Conv) and conservation (Cons) tillage
treatments for the wheel rows (W) and non-wheel (NW) rows at Marana, Arizona, June 2003.
Arizona Cotton Report (P-138) May 2004
42
2:52
Plot 3 (Conv)
Plot 4 (Cons)
2:24
Elapsed Time(hr)
Plot 5 (Cons)
Plot 6 (Conv)
1:55
1:26
0:57
0:28
0:00
100
200
300
400
500
600
700
800
900
1000
Distance from Head End (ft)
Figure 18. Average irrigation advance times in the conventional (CON) and conservation (CONS) tillage
treatments at Goodyear, Arizona. June 2003.
6:00
Elapsed Time(hr)
4:48
Conv-W
Conv-NW
Cons - W
Cons - NW
3:36
2:24
1:12
0:00
100
200
300
400
500
600
Distance from Head End (ft)
Figure 19. Average irrigation advance times in the conventional (Conv) and conservation (Cons) tillage
treatments for the wheel rows (W) and non-wheel (NW) rows at Maricopa, Arizona, June 2003.
Arizona Cotton Report (P-138) May 2004
43