CONSERVATION TILLAGE EFFECTS ON INFILTRATION AND
IRRIGATION ADVANCE TIMES
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 at sites in Marana, Coolidge and Goodyear,
Arizona, in the Fall of 2001, in a cotton-based, conservation tillage project. In
the 2002 cotton season, following cover and grain crops, soil and water
management assessments were made to evaluate the impact of conservation
tillage on surface irrigation performance. An additional site was added in the
winter of 2002 at Maricopa, Arizona. Analyses included soil texture, infiltration
rate and water advancement. At Coolidge, the Conservation plots had higher
infiltration rates and longer advance times than the Conventional plots in 2002,
2003 and 2004. 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, the Conventional plots infiltrated about one inch more and the opposite
occurred in 2004, where the Conservation plots infiltrated about 1 inch more
than the Conventional. The advance times for Marana showed the water in the
Conventional wheel rows to be the fastest. At Goodyear, the Conservation plots
infiltrated more than the Conventional plots in 2002. This also resulted in a
slower advance time for the Conservation plots. In 2003, due to tillage by the
grower, treatment effects could not be compared and the site was abandoned in
2004. At Maricopa, the Conservation plots infiltrated almost 2.2 inches more
water than the Conventional plots and the water reached the end of the field
three hours ahead of the fastest Conservation plot in 2003. In 2004, the
Conservation plot infiltrated just over 1½ inches more water than the
Conventional plots with the Conventional plots having faster advance times.
Seasonal irrigation water applications to each treatment were relatively equal
for all the 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 2004 irrigation data are
not yet available. The yield data show a significant difference between years
and different sites. In 2002, only the yields measured at Coolidge were
significantly different with the Conservation yielding higher than the
Conventional. This may have been due to the increase water application. In
2003, the opposite occurred and the Conventional plots yielded more than the
Conservation plots. This may have been due to herbicide damage. At Maricopa
the Conventional plot also yielded more than the Conservation plot in 2003 but
there was no measured difference in 2004. The Marana site had equal yields for
both treatments except for the final year, 2004, when the Conventional yielded
higher than the Conservation treatment. Indications are that conservation
tillage does impact irrigation performance and it may not be suitable for all
locations depending on soil type and field layout.
Arizona Cotton Report (P-142) May 2005
7
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
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. An additional site at the
Maricopa Agricultural Center was added in 2003. In 2004, the Goodyear site was not analyzed. 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.
Arizona Cotton Report (P-142) May 2005
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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.
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.
2004 Season
In 2003, the Coolidge site was moved, although it was still located on the same farm. The new field was
setup with furrows every 80 inches and cotton grown in beds located on either side of the furrow,
approximately 40 inches apart. The treatments remained the same but there were only two large fields,
one for each treatment with no replication. The Goodyear site was not analyzed during the 2004 season.
The Marana site remained exactly the same as 2003, as did 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,
Arizona Cotton Report (P-142) May 2005
9
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. In 2004, six plots were measured at Marana and Maricopa.
Only 2 plots were measured at the Coolidge site.
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 (2002-03) 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. In 2004 (Figure 3) the soil at the new site was
still dominated by sand, although the percent was less than the plots in 2002 and 2003. Also, the new
field had almost equal amounts of silt and clay.
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 4). 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.
Arizona Cotton Report (P-142) May 2005
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The Goodyear site had greater than 50% silt content throughout the upper 30 inches of the soil profile
(Figure 5). 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 6). 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).
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 7).
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 8). 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 9). 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 10). 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 11). The difference was less than one inch over
the four hour measurement period. At the Goodyear site, infiltration data were taken but the treatments
Arizona Cotton Report (P-142) May 2005
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for all plots were considered the same since deep ripping and land leveling took place during the spring of
2003 (Figure 12). 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 13. 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.
2004 Season
Infiltration measurements were conducted at the Coolidge site on May 13-14, 2004. The results were
similar to 2002 and 2003 with the conservation plots having a much greater infiltration rate (Figure 14).
The Marana data (Figure 15) was almost the direct opposite of the 2003 season in that the Conservation
plots infiltrated 5.8 inches in 4 hours and the Conventional plots averaged only 4.2 inches. At the
Maricopa site, the results were similar to the 2003 data with the Conservation plots averaging just over 4
inches of water infiltrated after 4 hours while the Conventional plots only infiltrated 2.6 inches. The
Goodyear site was not evaluated in 2004.
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.
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
Arizona Cotton Report (P-142) May 2005
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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.
2004Season
The Coolidge plots measured in 2004 were located at the same farm but in a different field. The
geometry was also different with furrow every 80 inches and large beds between them with 2 rows of
cotton planted on the bed. Thus, every furrow was a wheel row. The water in the Conventional plots had
an average time (average of 4 furrows) of 2 1/3 h to reach the end of the field (900 feet). The
Conservation plots to approximately one additional hour to reach the end (Figure 24). Field slope
measurements showed the field fairly level with a 0.02% slope from the head end of the field to the end of
the field.
The Marana plots in 2004 seemed to be “leveling off” with a slope of 0.001% from head to tail.
However, the advance time data (Figure 25) was similar to the past years with the Conventional wheel
row being the fastest and the Conventional Nonwheel being the slowest.
At the Maricopa site, the elevation data again showed a quick rise at the end of the field. Once this data
point was removed, it revealed that the slope had actually increased since 2003, and was now at 0.002%
instead of 0.00007% measured last year. The advance times (Figure 26) showed the two treatments
differed by almost 1 h and that both the wheel and nonwheel furrows reacted the same within treatments.
Arizona Cotton Report (P-142) May 2005
13
Irrigation Water Applied
A summary of the irrigation water applied to the cotton crops in the 2002, 2003 and 2004 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, 2003 and 2004 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 have 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
Throughout the study, the Conservation tillage plots have required approximately the same, or more
irrigation water than the Conventional plots at the same site. Yield data also showed that when a
statistical difference occurred between treatments, the Conventional treatment always yielded higher,
except for the 2002 Coolidge site. Thus, although conservation tillage does not always negatively effect
irrigation management, during the study period, it did not ever enhance irrigation management.
Therefore, the benefits of this practice must be found in other sectors of crop management besides
irrigation when using a surface irrigation system.
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).
Arizona Cotton Report (P-142) May 2005
14
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.
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-142) May 2005
15
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
2004
Coolidge
NA
NA
Marana
29.7*
29.0*
Maricopa
59.2
59.2
NA = not available; * does not include preplant irrigation application
Table 2. Yield data for the 2002, 2003 and 2004 cotton seasons.
Location
Season
Lint Yield (lbs/ac)*
2002
Conventional
Conservation
Coolidge
880a
1089b
Marana
1140a
1089ab
Goodyear
729a
751a
2003
Coolidge
1539a
1178b
Marana
1129a
946a
Goodyear
485a
531a
Maricopa
1141a
956b
2004
Coolidge
2023a
1600a
Marana
1693a
1378b
Maricopa
1522a
1548a
*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-142) May 2005
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A
B
D
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-142) May 2005
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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 (2002-03) conservation tillage experiment.
80.0
Soil Particle (%)
70.0
Sand
Silt
Clay
60.0
50.0
40.0
30.0
20.0
10.0
0.0
6
12
18
24
30
Soil Depth (inches)
Figure 3. The average sand, silt and clay content in the sandy clay loam soil at depths of 6 to 30 inches at
the Coolidge (2004) conservation tillage experiment.
Arizona Cotton Report (P-142) May 2005
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60
Sand
Soil Particle (%)
50
Silt
Clay
40
30
20
10
0
6
12
18
24
30
Soil Depth (inches)
Figure 4. 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.
70
Sand
Soil Particle (%)
60
Silt
Clay
50
40
30
20
10
0
6
12
18
24
30
Soil Depth (inches)
Figure 5. The average sand, silt and clay content at depth of 6 to 30 inches in the silty clay loam soil at
the Goodyear site.
Arizona Cotton Report (P-142) May 2005
19
70
%Sand
Soil Particle (%)
60
%Silt
%Clay
50
40
30
20
10
0
6
12
18
Soil Depth (inches)
24
30
Figure 6. The average sand, silt and clay content at depth of 6 to 30 inches in the silty clay loam soil at
the Maricopa site.
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 7. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Coolidge in May 2002.
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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 8. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Marana in June 2002.
1.6
Depth Infiltrated (inches)
1.4
1.2
1
0.8
0.6
Conventional
0.4
0.2
0
0.00
Conservation
0.50
1.00
1.50
2.00
2.50
Time (hr)
3.00
3.50
4.00
4.50
Figure 9. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Goodyear in June 2002.
Arizona Cotton Report (P-142) May 2005
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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 10. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Coolidge in May 2003.
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 11. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Marana in June 2003.
Arizona Cotton Report (P-142) May 2005
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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 12. Average depth of water infiltrated in the conventional and conservation tillage treatments at
Goodyear in June 2003.
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 13. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Maricopa in June 2003.
Arizona Cotton Report (P-142) May 2005
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8
7
Conventional
Depth Infiltrated (inches)
6
Conservation
5
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 14. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Coolidge in June 2004.
7
6
Depth Infiltrated (inches)
5
4
3
Conservation 2004
2
Conventional 2004
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 15. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Marana in June 2004.
Arizona Cotton Report (P-142) May 2005
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4.5
Depth Infiltrated (inches)
4
Conventional
3.5
Conservation
3
2.5
2
1.5
1
0.5
0
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
Time (hr)
Figure 16. A comparison of the average depth of water infiltrated in the conventional and conservation
tillage treatments at Maricopa in June 2004.
8:24
Conv W
7:12
Elapsed Time (hr)
Cons W
6:00
Cons NW
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 End (ft)
Figure 17. 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-142) May 2005
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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 18. 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.
Elapsed Time (hr)
4:19
3:50
Conv
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 19. Average irrigation advance times in the conventional (Conv) and conservation (Cons) tillage
treatments at Goodyear, Arizona, June 2002.
Arizona Cotton Report (P-142) May 2005
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6:00
Conv W
Conv NW
Cons W
Cons NW
Elapsed Time(hr)
4:48
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 20. 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
Conv W
Conv NW
Cons W
Cons NW
Elapsed Time(hr)
6:00
4:48
3:36
2:24
1:12
0:00
100
200
300
400
500
600
Distance from Head End (ft)
Figure 21. 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-142) May 2005
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2:52
Plot 3 (Conv)
Elapsed Time(hr)
2:24
Plot 6 (Conv)
Plot 4 (Cons)
1:55
Plot 5 (Cons)
1:26
0:57
0:28
0:00
100
200
300
400
500
600
700
800
900
1000
Distance from Head End (ft)
Figure 22. 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 23. 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.
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3:50
Elapsed Time(hr)
3:21
Conv
2:52
Cons
2:24
1:55
1:26
0:57
0:28
0:00
0
100
200
300
400
500
600
700
800
900
Distance from Head End (ft)
Figure 24. Average irrigation advance times in the conventional (Conv) and conservation (Cons) tillage
treatments at Coolidge, Arizona, June 2004.
18:00
Conv W
Conv NW
Cons W
Cons NW
Elapsed Time(hr)
16:48
15:36
14:24
13:12
12:00
0
100
200
300
400
500
600
Distance from Head End (ft)
Figure 25. 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 2004.
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3:21
Conv W
Conv NW
Cons W
Cons NW
Elapsed Time(hr)
2:52
2:24
1:55
1:26
0:57
0:28
0:00
0
100
200
300
400
500
600
Distance from Head End (ft)
Figure 26. Average irrigation advance times in conventional (Conv) and conservation (Cons) tillage
treatments for the wheel rows (W) and non-wheel (NW) rows at Maricopa, Arizona, June 2004.
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