Final Report to Delaware Soybean Board
Submitted January 16, 2014
Received January 16, 2014
Delaware Soybean Board (susanne@hammondmedia.com)
Evaluating the Response of Full Season and Double Cropped Soybeans in Narrow and Wide Rows
to Various Soil Moisture Levels
Cory Whaley, James Adkins, and Phillip Sylvester
OBJECTIVES
1) Evaluate the effects of various soil moisture levels and row widths on growth and yield of full season
and double cropped soybeans.
2) Determine the optimal irrigation management strategy for full season and double cropped soybeans to
maximize yield and profitability.
3) Determine the optimal row width for irrigated full season and double cropped soybeans to maximize
yield and profitability.
SUMMARY OF 2012 AND 2013 TRIALS
2012 (1st year of trials). In 2012, rainfall totals in May (0.5”), June (2.5”), July (2.5”), and September
(2.8”) were below average, but rainfall was well above average in August (10.6”).
In the full season study, average yield in plots that received irrigation ranged from 63 to 70 bu/A
compared to 54 bu/A in plots that received no irrigation. The amount of water applied based on the
irrigation strategy ranged from 5.3” to 9.6”. The irrigation strategy that produced the greatest yield (70
bu/A) was when irrigation was applied at a reduced amount (>30% available soil moisture) until the
R5/R6 growth stage and then >50% available soil moisture until maturity. This irrigation strategy also
required the least amount of water applied (5.3”). There was no yield advantage in irrigating to maintain
>50% available soil moisture until Mid-August this year. Soybeans in all row widths responded similarly
to each irrigation strategy, but there was an overall yield difference between row widths. Average
soybean yield was 67 bu/A in 15” rows, 64 bu/A in 7” rows, and 61 bu/A in 30” rows.
In the double crop study, average yield in plots that received irrigation ranged from 58 to 61 bu/A
compared to 58 bu/A in plots that received no irrigation. The amount of water applied based on the
irrigation strategy ranged from 2.2” to 6.6”. The above average rainfall in August had a significant effect
on soybean yield. Soybeans in all row widths responded similarly to each irrigation strategy, but there
was an overall yield difference between row widths. Yield was greatest in the 15” rows at 64 bu/A,
followed by the 30” rows at 58 bu/A, and then the 7” rows at 55 bu/A. Final stand in the 7” rows was
107,000 plants/A compared to 169,522 plants/A in the 15” rows, and 154,427 plants/A in the 30” rows.
The reduced plant stand in the 7” rows compared to the 15” and 30” rows may have limited yield
potential.
1
2013 (2nd year of trials). In 2013, rainfall totals in June (10.4”), July (6.9”), August (6.5”) and October
(6.1”) were above average, but rainfall was well below average in September (0.7”).
In the full season soybean study, soybeans were planted on May 19. Average yield in plots that received
irrigation ranged from 65 to 73 bu/A compared to 69 bu/A in plots that received no irrigation. The
amount of water applied based on the irrigation strategy ranged from 4.3” to 7.0”. The irrigation strategy
that produced the greatest yield (73 bu/A) was when irrigation was applied at a limited amount (>30%
available moisture) until the R3/R4 growth stage and then applied to maintain available soil moisture
>50% until maturity and was also the irrigation strategy with the least amount of water applied (4.3”).
However, yield attained by this irrigation strategy was not statistically different from the no irrigation
treatment and strategies that applied no irrigation until R1/R2 and limited irrigation to R1/R2 and R5/R6,
where yields ranged from 69 to 71 bu/A. The two irrigation strategies, full season irrigation (65 bu/A)
and an ET based program (66 bu/A), that maintained soil moisture >50% all season were the only two
strategies that produced less yield than the no irrigation treatment. Soybeans planted in 7.5”, 15”, and 30”
row widths yielded similarly to each irrigation strategy, but there was an overall yield difference between
row widths. Average soybean yield was 72.8 bu/A in 7.5” rows, 68.6 bu/A in 15” rows, and 66.4 bu/A in
30” rows.
In the double crop study, soybeans were planted on July 19. Average yield in plots that received
irrigation ranged from 38 to 45 bu/A compared to 31 bu/A in plots that received no irrigation. The
amount of water applied based on the irrigation strategy ranged from 4.7” to 6.7”. The irrigation strategy
that produced the greatest yield (45 bu/A) was when irrigation was applied to maintain soil moisture
>50% all season. Yield from irrigation strategies where soil moisture was maintained >50% available
moisture at R1/R2 until maturity, except the treatment of limited irrigation to R1/R2 then >50% available
moisture to R3/R4 then >70% available moisture to maturity, yielded similarly at 42 to 45 bu/A. The
limited irrigation to R3/R4 then >50% available moisture to maturity, limited irrigation to R5/R6 then
>50% available moisture to maturity, and limited irrigation to R1/R2 then >50% available moisture to
R3/R4 then >70% available moisture to maturity strategies produced the lowest yields at 39, 38, and 37
bu/A, respectively. Soybeans planted in 7.5”, 15”, and 30” row widths yielded similarly to each irrigation
strategy, but there was an overall yield difference between row widths. Average soybean yield was 41
bu/A in 7.5” rows, 41 bu/A in 15” rows, and 37 bu/A in 30” rows.
MATERIALS AND METHODS
Two studies were conducted in 2013 to determine the response of full season and double cropped
soybeans to various soil moisture levels and row widths. Both studies were conducted under a variable
rate four tower center pivot irrigation system located on the University of Delaware’s Warrington
Irrigation Research Farm in Harbeson, DE.
Treatments. In both projects, the plots measured 30 ft by 30 ft and consisted of soybeans planted in 3
row widths. The row widths were 7.5 in., 15 in., and 30 in. Each plot received one of the following
irrigation treatments. All treatments were replicated five times.
2
Irrigation Treatments:
1. No irrigation.
2. KanSched2 - Evapotranspiration (ET) based irrigation management using the Delaware
Environmental Observing System’s weather station located on the research farm and the
commonly accepted soybean crop coefficients.
3. Full season irrigation (>50% soil moisture throughout the season).
4. No irrigation until flowering (R1 to R2) then >50% soil moisture.
5. Limited irrigation (>30% soil moisture) until flowering (R1 to R2) then >50% soil moisture.
6. Limited irrigation (>30% soil moisture) until flowering (R1 to R2) then >50% soil moisture until
pod development (R3 to R4) then >70% soil moisture.
7. Limited irrigation (>30% soil moisture) until pod development (R3 to R4) then >50% moisture.
8. Limited irrigation (>30% soil moisture) until seed development (R5 to R6) then >50% soil
moisture.
Field Operations. The entire study area was treated identically for all production inputs except
irrigation. Fertilizer was applied based on the University of Delaware recommendations for soybean.
Soybeans in both studies were grown under conventional tillage practices. Soybeans were planted in 7.5
in. rows with a Great Plains 1520P drill and in 15 in. and 30 in. rows with a Kinze planter with brush
meters. Planting dates, soybean varieties, seeding rates, pesticide applications, and harvest dates for both
studies are presented in Table 1.
Table 1. Planting date, variety, seeding rate, pesticide applications, and harvest date for the
full season and double crop soybean studies.
Full Season
Double Crop
Operation
Study
Study
Planting Date
5/19/13
7/19/13
Variety
Target Seeding Rate/A
Asgrow 4130
Asgrow 3931
165,000
225,000
7/18/13
--
--
7/19/13
--
9/5/13
8/24/13
--
10/29/13
11/15/13
Pesticide Applications
Glyphosate 28 oz/A + Reflex 1.25 pt/A +
Warrior II 1.92 oz/A
Canopy 4 oz/A + Glyphosate 28 oz/A +
Warrior II 1.92 oz/A
Glyphosate 24 oz/A + Warrior II 1.92 oz/A
Priaxor 6 oz/A + Hero 10.3 oz/A +
Maximizer 1 pt/A
Harvest Date
Soil Moisture Monitoring to Trigger Irrigation Treatments. Soil moisture was monitored in each plot
using Watermark soil moisture sensors placed at 4 in., 10 in., and 16 in. below the soil line. Sensors were
placed in the 15 in. row width section of each plot. A Watermark 950T transmitter was used at all
moisture monitoring locations to wirelessly transmit data to a Watermark 950R data logging receiver.
3
Moisture data was viewed and interpreted daily to determine if any treatments required irrigation.
Irrigation was applied to plots when soil moisture at the 4 in., 10 in., or 16 in. depth reached the specific
irrigation treatment requirement. KanSched2, an irrigation scheduling program, was used to trigger the
ET based irrigation treatment. ET data was obtained from a Delaware Environmental Observing System
(DEOS) weather station located on the irrigation research farm.
Data Collected. Plant stand counts were recorded in each row width and were averaged within each row
width (Table 2). In-season plant heights, canopy development, and growth stages (Table 3) were
recorded on multiple dates. In addition, lodging and green stem were recorded at harvest. Soybean yield,
moisture, and test weight were determined by harvesting the middle rows of each plot (12 rows in the 7.5
in. width, 5 rows in the 15 in. width, and 2 rows in the 30 in. width) with a Massey Ferguson 8XP plot
combine. Soybean yield was adjusted to 13% moisture.
Table 2. Final average plants per acre by
row width in the full season and double
crop soybean studies.
Full
Double
Row
Season
Crop
Width
Study
Study
________
Avg. Plants/A _________
7.5 inch
171,173
195,077
Table 3. Soybean growth stages by date for the full
season and double crop soybean studies.
Full
Double
Growth Growth Stage Season
Crop
Stage
Description
Study
Study
___________
Date __________
V2
2-trifoliolate
6/19/13
8/10/13
V4
4-trifoliolate
6/24/13
8/20/13
15 inch
163,786
195,532
V6
6-trifoliolate
6/29/13
--
30 inch
170,755
196,988
R1
Begin Flower
7/1/13
8/23/13
R2
Full Flower
7/9/13
8/29/13
R3
Begin Pod
7/21/13
9/4/13
R4
Full Pod
8/5/13
9/9/13
R5
Begin Seed
8/20/13
9/16/13
R6
Full Seed
9/4/13
9/25/13
R7
Begin Maturity
9/20/13
10/23/13
R8
Full Maturity
10/2/13
11/5/13
Data Analysis. Data was analyzed using the Proc GLM procedure in SAS and treatments means
compared using the Least Significant Difference (LSD) test at the 5% probability level. There were no
significant irrigation treatment by row width interactions for any data. Therefore, data for each row width
was combined and analyzed by irrigation treatment. Total water applied for each irrigation treatment was
determined and the economic implications of each irrigation management strategy were calculated based
on soybean yield, soybean selling price, and irrigation energy costs.
4
Figure 1. Bi-weekly rainfall total at the study site in Harbeson, DE in 2013.
Bi-Weekly Rainfall at Harbeson, DE 2013
8
7.36
7
5.98
Rainfall (in.)
6
5.8
5
4.4
4
3.03
3
2.05
2
1
0.9
0.52
0.27
0.42
0.34
0
5/16 to
5/31
6/1 to
6/15
6/16 to
6/30
7/1 to
7/15
7/16 to
7/31
8/1 to
8/15
8/16 to
8/31
9/1 to
9/15
9/16 to 10/1 to 10/16 to
9/30
10/15 10/31
Date Range
RESULTS AND DISCUSSION
In-Season Rainfall. Figure 1 shows the bi-weekly rainfall at the study site in Harbeson, DE in 2013.
Overall, rainfall totals in June (10.4”), July (6.9”), August (6.5”) and October (6.1”) were above average,
but rainfall in September (0.7”) was below average. Most of the July rainfall occurred from July 1 to July
15. Only 0.9” of rain was received from July 16 to July 31.
Irrigation Applied. Bi-weekly and total irrigation applied for each treatment in the full season and
double crop studies are shown in Figure 2 and Figure 3, respectively.
Full Season Study – Irrigation applied for all irrigated treatments ranged from 4.3 in. to 7.0 in. (Table 6).
Rainfall in June was well above average (Figure 1). The full season irrigation treatment and the limited
irrigation to R1/R2 then >50% to R3/R4 then >70% were the only treatments that received irrigation in
June and was 0.6 in. and <0.1 in., respectively. In July, treatments that held moisture >50% at R1/R2
received between 2.5 in. and 2.8 in. of irrigation, whereas the two limited irrigation treatments to later
growth stages (R3/R4 and R5/R6) received 1.6 to 1.8 in. of irrigation. Irrigation totals for all treatments
in August ranged from 0.4 in. to 1.3 in. for all treatments due to near sufficient rainfall. In September,
irrigation for all treatments ranged from 1.6 in. to 2.4 in due to below average rainfall.
Double Crop Study – Irrigation applied for all irrigated treatments ranged from 4.7 in. to 6.7 in. (Table 9;
Figure 3). Rainfall after planting until 8/16 was adequate to support vegetative growth (Figure 1).
Flowering (R1) began on 8/23 (Table 3). In August, irrigation for all treatments ranged from 0.0 in. to
0.9 in. In September, irrigation for all treatments ranged from 3.8 in. to 4.8 in. Irrigation applied in
October ranged from 0.4 in. to 1.0 in.
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Soybean Growth.
Full Season Study – Soybean heights were measured on 7/24, 8/16, and 10/28. Canopy development was
recorded on 7/24.
Plant Height by Irrigation Treatment. On 7/24 at stage R3, plant height in the no irrigation treatment was
21.9 in. compared to 23.1 in. to 26.7 in. in treatments that received irrigation (Table 4). On 8/16 at stage
late R4, plant height in the no irrigation treatment was 41.8 in. compared to 41.6 in. to 45.5 in. in
treatments that received irrigation. Between 7/24 and 8/16 soybean height increased approximately 20 in.
in all plots. Between 8/16 and 10/28, plant height increased approximately 1.5 in. At all sampling dates,
total irrigation applied by each treatment did not correlate with plant height. Rainfall was most likely
adequate for vegetative growth and it is possible that field variability accounted for the height differences
noted.
Plant Height by Row Width. Plant heights were not significantly different between row widths on any
collection date (Table 5).
Canopy Closure by Irrigation Treatment. Plant canopy closure was not significantly different between
irrigation treatment on any collection date (Table 4).
Canopy Closure by Row Width. On 7/24 at stage R3, soybeans in the 7.5 in. and 15 in. row width had
achieved full canopy and the 30 in. row widths were 1.6 in. from full canopy (Table 5). By 8/16 at stage
late R4, the 30 in. row widths were at full canopy.
Double Crop Study – Soybean heights were measured on 9/6, 10/8, and 10/19. Canopy closure was
recorded on 9/6 and 10/8.
Plant Height by Irrigation Treatment. Plant heights on 9/6 at stage R3 were 14.8 in. in the no irrigation
treatment compared to 14.0 in. to 16.4 in. in irrigated treatments (Table 7). On 10/8 at stage R6, soybeans
were significantly taller in plots where soil moisture was held >50% at R1/R2 compared to the no
irrigation treatment and limited irrigation until R3/R4 and limited irrigation until R5/R6 treatments.
Rainfall was below average in September and is reflected in the vegetative growth attained in those three
treatments. Plants had reached full height by R6.
Plant Height by Row Width. On 11/4 just before harvest, plant height by row width was 20.5 in., 19.6 in.,
and 19.1 in. in 7.5 in., 15 in., and 30 in. row widths, respectively (Table 8).
Canopy Closure by Irrigation Treatment. Canopy closure was similar between all irrigated treatments on
the 9/6 and the 10/8 collection dates (Table 7).
Canopy Closure by Row Width. At stage R3 on 9/6, the 7.5 in. and 15 in. row widths were at full canopy
(Table 8). The 30 in. row width was 8.7 in. from full canopy. On 10/8, the 30 in. row width was 3.5 in.
from canopy closure.
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Lodging and Yield.
Full Season Study – Soybeans were harvested on 10/29. Lodging ratings were taken before harvest.
Lodging by Irrigation Treatment. There were only slight differences in lodging between all treatments,
which ranged from 2.0 to 2.7 on a scale of 0 to 5 (0=no lodging; 5 =maximum lodging) (Table 6).
Lodging by Row Width. Lodging at harvest was slightly higher in the 30 in. row width compared to the
7.5 in. and 15 in. row widths (Table 5). Lodging ratings ranged from 2.1 to 2.5.
Yield by Irrigation Treatment. Yield in the irrigated treatments ranged from 65 to 73 bu/A compared to
69 bu/A in the no irrigation treatment (Figure 2; Table 6). The highest yielding treatment was the limited
irrigation to R3/R4, which was also the treatment with the least amount of water applied. The two full
season irrigation treatments (>50% full season and KanSched2) were the only two treatments that
produced less yield than the no irrigation treatment.
Yield by Row Width. Yield between row widths ranged from 66.4 to 72.8 bu/A (Table 5; Figure 4).
Yield in the 7.5 in. row was greatest at 72.8 bu/A. Yield in the 15 in. and 30 in. row widths were not
statistically different and were 68.6 bu/A and 66.4 bu/A, respectively.
Double Crop Study – Soybeans were harvested on 11/15. There was no lodging to rate.
Yield by Irrigation Treatment. Yield in the irrigated treatments ranged from 38 to 45 bu/A compared to
31 bu/A in the no irrigation treatment (Figure 3; Table 9). The highest yielding treatment was the full
season irrigation treatment. Yield in treatments where soil moisture was maintained >50% moisture at
R1/R2, except the treatment of limited irrigation to R1/R2 then >50% to R3/R4 then >70%, yielded
similarly at 42 to 45 bu/A. The limited irrigation to R3/R4, limited irrigation to R5/R6, and limited
irrigation to R1/R2 then >50% to R3/R4 then >70% treatments produced the lowest yields at 39, 38, and
37 bu/A, respectively.
Yield by Row Width. Yield ranged from 37 to 41 bu/A by row width (Table 8; Figure 4). Yield in the 7.5
in. and 15 in. row widths was 41 bu/A and was greater than the 37 bu/A produced in the 30 in. row width.
SUMMARY
Full Season Study – Effect of Irrigation Treatment. Average yield in plots that received irrigation ranged
from 65 to 73 bu/A compared to 69 bu/A in plots that received no irrigation. The amount of water
applied based on the irrigation strategy ranged from 4.3” to 7.0”. The irrigation strategy that produced the
greatest yield (73 bu/A) was when irrigation was applied at a limited amount (>30% available moisture)
until the R3/R4 growth stage and then applied to maintain available soil moisture >50% until maturity
and was also the irrigation strategy with the least amount of water applied (4.3 in.). However, yield
attained by this irrigation strategy was not statistically different from the no irrigation treatment and
strategies that applied no irrigation until R1/R2 and limited irrigation to R1/R2 and R5/R6, where yields
ranged from 69 to 71 bu/A. The two irrigation strategies, full season irrigation (65 bu/A) and an ET
7
based program (66 bu/A) that maintained soil moisture >50% all season were the only two strategies that
produced less yield than the no irrigation treatment.
Effect of Row Width. Soybeans planted in 7.5”, 15”, and 30” row widths yielded similarly to each
irrigation strategy, but there was an overall yield difference between row widths. Average soybean yield
was 72.8 bu/A in 7.5” rows, 68.6 bu/A in 15” rows, and 66.4 bu/A in 30” rows.
Double Crop Study – Effect of Irrigation Treatment. Average yield in plots that received irrigation
ranged from 38 to 45 bu/A compared to 31 bu/A in plots that received no irrigation. The amount of water
applied based on the irrigation strategy ranged from 4.7” to 6.7”. The irrigation strategy that produced the
greatest yield (45 bu/A) was when irrigation was applied to maintain soil moisture >50% all season.
Yield from irrigation strategies where soil moisture was maintained >50% available moisture at R1/R2
until maturity, except the treatment of limited irrigation to R1/R2 then >50% available moisture to R3/R4
then >70% available moisture to maturity, yielded similarly at 42 to 45 bu/A. The limited irrigation to
R3/R4 then >50% available moisture to maturity, limited irrigation to R5/R6 then >50% available
moisture to maturity, and limited irrigation to R1/R2 then >50% available moisture to R3/R4 then >70%
available moisture to maturity strategies produced the lowest yields at 39, 38, and 37 bu/A, respectively.
Effect of Row Width. Soybeans planted in 7.5”, 15”, and 30” row widths yielded similarly to each
irrigation strategy, but there was an overall yield difference between row widths. Average soybean yield
was 41 bu/A in 7.5” rows, 41 bu/A in 15” rows, and 37 bu/A in 30” rows.
8
Figure 2. Full Season Study – Soybean yield and total irrigation applied bi-weekly by treatment. Each color represents the total amount of
irrigation applied during the date range listed. The top of the bar column represents the total irrigation applied for the season.
Full Season Study 2013 - Yield and Total Irrigation Applied by Treatment and
Date
73 a
9
71 ab
69 abc2
71 ab
75
69 abc
66 cd
70
65 d
10/1 to 10/15
7
65
6
60
5
55
4
50
3
45
2
40
9/16 to 9/30
9/1 to 9/15
Yield (bu/A)
Irrigation (in.)
8
71 ab
8/16 to 8/31
8/1 to 8/15
7/16 to 7/31
7/1 to 7/15
6/16 to 6/30
Yield
1
35
0
30
No Irr.
KanSched2 Full Season Irr. No Irr. to
(ET)
R1/R2 then
>50%
Limited Irr. to Limited Irr. to Limited Irr. to Limited Irr. to
R1/R2 then
R1/R2 then
R3/R4 then
R5/R6 then
>50%
>50% to R3/R4
>50%
>50%
then >70%
Irrigation Treatment1
1
Treatments with limited irrigation were kept at >30% available soil moisture (0% moisture = dry; 100% moisture = wet).
Treatment means followed by the same letter are not significantly different.
2
9
Figure 3. Double Crop Study – Soybean yield and total irrigation applied bi-weekly by treatment. Each color represents the total amount of
irrigation applied during the date range listed. The top of the bar column represents the total irrigation applied for the season.
Double Crop Study 2013 - Yield and Total Irrigation Applied by Treatment
and Date
8
50
45 a
43 ab
7
42 bc
45
42 abc
39 cd
37 d
38 d
40
6
5
4
35
10/16 to 10/31
30
10/1 to 10/15
25
20
3
15
2
10
1
5
0
0
No Irr.
KanSched2 Full Season Irr. No Irr. to
(ET)
R1/R2 then
>50%
Limited Irr. to Limited Irr. to Limited Irr. to Limited Irr. to
R1/R2 then
R1/R2 then
R3/R4 then
R5/R6 then
>50%
>50% to R3/R4
>50%
>50%
then >70%
Irrigation Treatment1
1
Treatments with limited irrigation were kept at >30% available soil moisture (0% moisture = dry; 100% moisture = wet).
Treatment means followed by the same letter are not significantly different.
2
10
Yield (bu/A)
Irrigation (in.)
31 e2
9/16 to 9/31
9/1 to 9/15
8/16 to 8/31
Yield
Figure 4. Full Season and Double Crop Study – Row spacing effect on soybean yield.
Row Spacing Effect on Soybean Yield in Full
Season and Double Crop Soybean in 2013
Full Season
Double Crop
80
75
73 a1
69 b
70
66 b
Yield (Bu/A)
65
60
55
50
45
41 a
41 a
37 b
40
35
30
25
20
7.5 "
15"
Row Spacing
30"
1
Treatment means followed by the same letter are not significantly different.
11
Table 4. Full Season Soybean Study - Irrigation treatment effect on soybean plant height and canopy closure.
Plant Height
Canopy2
1
Irrigation Treatment
7/24/13
8/16/13
10/28/13
7/24/13
_____________________
___
in. _____________________
in. ___
No Irr.
21.9 d2
41.8 b
42.8 d
0.9 a
KanSched2 (ET)
23.1 cd
41.6 b
43.3 cd
0.6 ab
Full Season Irr.
24.5 bc
43.5 ab
44.9 abcd
0.4 ab
No Irr. to R1/R2 then >50%
23.6 bcd
43.7 ab
44.6 bcd
0.3 ab
Limited Irr. to R1/R2 then >50%
26.7 a
45.5 a
47.2 a
0.1 b
Limited Irr. to R1/R2 then >50%
to R3/R4 then >70%
25.4 ab
45.3 a
46.8 ab
0.5 ab
Limited Irr. to R3/R4 then >50%
23.7 bcd
45.3 a
46.1 ab
0.8 ab
Limited Irr. to R5/R6 then >50%
25.1 ab
44.5 a
45.3 abc
0.6 ab
LSD
1.9
2.3
2.3
NS
Treatments with limited irrigation were kept at >30% available soil moisture (0% moisture = dry; 100% moisture = wet).
2
Canopy was measured as the width between adjacent rows. A canopy measurement of zero would indicate that plants were at full canopy.
3
Treatment means followed by the same letter are not significantly different.
1
Table 5. Full Season Soybean Study – Row width effect on soybean plant height, canopy closure, node number, lodging, and yield.
Row
Plant Height
Canopy2
Width1
7/24/13
8/16/13
10/28/13
7/24/13
Lodging3
Yield
____________________
____________________
____
___
___
in.
in.
# ___
bu/A
4
7.5 in.
23.5 b
44.5 a
45.1 a
0.0 b
2.3 ab
72.8 a
15 in.
24.9 a
44.3 a
44.7 a
0.0 b
2.1 b
68.6 b
30 in.
24.2 ab
42.9 a
45.6 a
1.6 a
2.5 a
66.4 b
LSD
NS
NS
NS
0.5
0.3
2.3
Average plant stand/A for 7 in. = 171,173; 15 in. = 163,786; 30 in. = 170,755.
2
Canopy was measured as the width between adjacent rows. A canopy measurement of zero would indicate that plants were at full canopy.
3
Lodging was rated on a scale of 0 to 5 (0 = no lodging; 5 = maximum lodging).
4
Treatment means followed by the same letter are not significantly different.
1
12
Table 6. Full Season Soybean Study – Irrigation treatment effect on soybean lodging and yield, total irrigation applied, irrigation energy cost per
acre, and gross income at multiple soybean prices.
Total
Irrigation
Irrigation
Energy
Gross Income minus Irrigation
Irrigation Treatment1
Lodging2
Yield
Applied
Cost3
Energy Cost4
___
___
___
___
_
_
5
#
bu/A
in.
$/Acre
$8.00/bu $10.00/bu $12.00/bu
6
No Irr.
2.1 c
69.0 abc
0.0 d
0.00
552
690
828
KanSched2 (ET)
2.0 c
65.6 cd
5.9 abc
35.40
489
621
752
Full Season Irr.
2.7 a
64.5 d
6.3 ab
37.80
478
607
736
No Irr. to R1/R2 then >50%
2.2 bc
71.1 ab
5.4 abc
32.40
536
679
821
Limited Irr. to R1/R2 then >50%
2.7 a
69.0 abc
5.5 abc
33.00
517
655
793
Limited Irr. to R1/R2 then >50%
to R3/R4 then >70%
2.3 abc
70.9 ab
7.0 a
42.00
525
667
809
Limited Irr. to R3/R4 then >50%
2.0 c
72.8 a
4.3 c
25.80
557
702
848
Limited Irr. to R5/R6 then >50%
2.3 abc
71.4 ab
4.8 bc
28.80
542
685
828
LSD
0.5
3.8
1.7
Treatments with limited irrigation were kept at >30% available soil moisture (0% moisture = dry; 100% moisture = wet).
2
Lodging was rated on a scale of 0 to 5 (0 = no lodging; 5 = maximum lodging).
3
Irrigation energy costs were calculated assuming the cost to pump 1 acre-inch of water is $6.00.
4
Gross income was calculated based on soybean price, yield, and irrigation cost.
5
Gross income minus irrigation energy cost at the expected soybean selling price.
6
Treatment means followed by the same letter are not significantly different.
1
13
Table 7. Double Crop Soybean Study - Irrigation treatment effect on soybean plant height and canopy closure.
Plant Height
Canopy2
1
Irrigation Treatment
9/6/13
10/8/13
11/4/13
9/6/13
10/8/13
_____________________
_____________________
__________
in.
in. __________
3
No Irr.
14.8 bc
18.5 c
17.9 e
2.9 ab
1.5 ab
KanSched2 (ET)
15.4 abc
20.8 ab
20.2 abc
2.3 b
0.7 b
Full Season Irr.
16.4 a
21.8 ab
21.5 a
2.3 b
0.5 b
No Irr. to R1/R2 then >50%
14.8 bc
20.5 b
19.7 bcd
3.2 ab
1.2 ab
Limited Irr. to R1/R2 then >50%
15.7 ab
22.2 a
21.2 ab
3.0 ab
1.4 ab
Limited Irr. to R1/R2 then >50%
to R3/R4 then >70%
15.6 ab
21.0 ab
20.1 abc
2.9 ab
0.7 b
Limited Irr. to R3/R4 then >50%
14.3 bc
18.4 c
18.8 cde
3.4 ab
1.2 ab
Limited Irr. to R5/R6 then >50%
14.0 c
18.0 c
18.3 de
4.0 a
2.2 a
LSD
1.4
1.6
1.7
NS
NS
Treatments with limited irrigation were kept at >30% available soil moisture (0% moisture = dry; 100% moisture = wet).
2
Canopy was measured as the width between adjacent rows. A canopy measurement of
zero would indicate that plants were at full canopy.
3
Treatment means followed by the same letter are not significantly different.
1
Table 8. Double Crop Soybean Study – Row width effect on soybean plant height, canopy closure, lodging, and yield.
Row
Plant Height
Canopy2
Width1
9/6/13
10/8/13
11/4/13
9/6/13
10/8/13
Yield
_____________________
___________
in. ___________________
in. __________
bu/A
3
7.5 in.
16.1 a
20.5 a
20.5 a
0.0 b
0.0 b
41.0 a
15 in.
14.5 b
20.6 a
19.6 ab
0.3 b
0.0 b
41.0 a
30 in.
14.8 b
19.3 b
19.1 b
8.7 a
3.5 a
37.0 b
LSD
0.9
1.0
1.0
0.7
0.7
2.1
Average plant stand/A for 7 in. = 195,077; 15 in. = 195,532; 30 in. = 196,988. Planting depth and conditions reduced emergence in 7 in. rows.
2
Canopy was measured as the width between adjacent rows. A canopy measurement of zero would indicate that plants were at full canopy.
3
Treatment means followed by the same letter are not significantly different.
14
1
Table 9. Double Crop Soybean Study – Irrigation treatment effect on soybean yield, total irrigation applied, irrigation energy cost per acre, and
gross income at multiple soybean prices.
Total
Irrigation
Irrigation
Energy
Gross Income minus Irrigation
Irrigation Treatment1
Yield
Applied
Cost2
Energy Cost3
___
_
bu/A
in. ___
$/Acre _
$8.00/bu4 $12.00/bu $16.00/bu
5
No Irr.
31.1 e
0.5 b
3.00
246
308
370
KanSched2 (ET)
42.9 ab
5.3 a
31.80
311
397
483
Full Season Irr.
45.4 a
6.7 a
40.20
323
414
505
No Irr. to R1/R2 then >50%
41.6 bc
6.0 a
36.00
297
380
463
Limited Irr. to R1/R2 then >50%
42.2 abc
6.1 a
36.60
301
385
470
Limited Irr. to R1/R2 then >50%
to R3/R4 then >70%
37.5 d
5.5 a
33.00
267
342
417
Limited Irr. to R3/R4 then >50%
38.9 cd
5.6 a
33.60
278
355
433
Limited Irr. to R5/R6 then >50%
37.9 d
4.7 a
28.20
275
351
427
LSD
3.5
2.1
Treatments with limited irrigation were kept at >30% available soil moisture (0% moisture = dry; 100% moisture = wet).
2
Irrigation energy costs were calculated assuming the cost to pump 1 acre-inch of water is $6.00.
3
Gross income was calculated based on soybean price, yield, and irrigation energy cost.
4
Gross income minus irrigation energy cost at the expected soybean selling price.
5
Treatment means followed by the same letter are not significantly different.
1
15