27
Sugarbeet Fertility
K.A. Rykbost and R.L. Dovel l
INTRODUCTION
Petiole analyses from several commercial sugarbeet crops in 1990 indicated a
general trend of deficient levels of sulfur and calcium. Deficiencies in
several minor elements were also observed with zinc, copper, and boron being
borderline or deficient in every case. Experience with cereals has shown that
banding an acidifying fertilizer has improved availability of micronutrients
and grain yields on Klamath Basin soils. Gypsum is commonly used in local
potato crops for improving soil tilth and also for nutritional benefits. A
preliminary study was established at KES in 1991 to evaluate the response of
sugarbeets to broadcast vs. banded starter fertilizer and gypsum.
METHODS
Soil conditions are described in the report on the official variety trial.
Previous crops at this site were barley in 1989 and 1990 preceded by several
years of alfalfa. The field was plowed on April 1. The experiment was a
split-plot design with six replications. Main-plots were four 32-inch rows 32
feet long. Starter fertilizer (320 lbs/A of 16-16-16) was broadcast and
harrow-incorporated on April 15, or banded at 4-inch depth on both sides of
rows at the time of bed formation on May 2. Split-plots were 16-foot sections
of eight rows with no gypsum or 1.0 T/A of gypsum broadcast and harrowincorporated on April 15. Beds were firmly compacted with a brillion roller.
HH55 seed was planted at one-half inch depth with a hand-operated planetjunior type planter at approximately 12 seeds per foot on May 3. Beets were
hand-thinned to a 6-inch spacing on June 7. Cultural practices were the same
as described for other sugarbeet experiments.
Petiole samples were taken from each plot on August 2 and September 4.
Beets were topped with a flail chopper and harvested on October 17. The
number and weight of all beets from the center two rows of each plot were
recorded. All beets from one row were analyzed for tare and sugar content.
1/ Superintendent/Associate Professor and Assistant Professor, respectively,
Klamath Experiment Station, Klamath Falls, OR.
Acknowledgment: Financial support of this study by the Oregon Center for
Applied Agricultural Research and the California Beet Growers' Association is
gratefully recognized.
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RESULTS AND DISCUSSION
Treatments imposed had no visible effects on canopy development or crop
health and minimal effects on sugarbeet production. Petiole analysis showed
slightly higher nitrate nitrogen levels in beets with banded starter fertilizer (Table 1). Differences were not statistically significant. The application of 1.0 tons/A of agricultural gypsum did not affect petiole content of
calcium, sulfur, or other nutrients.
Plant populations were very uniform throughout the experiment and close
to the target population of 35,000 beets/A (Table 2). Beet yields were 0.7
tons/A higher when starter fertilizer was banded. This difference was not
statistically significant. Fertilization method did not affect sugar content.
The application of gypsum had no effect on beet yields but appeared to depress
sugar content slightly.
The 30 tons/A yields were nearly identical to yields achieved by HH55 in
the planting date study for May 3 planting. However, sugar content averaged
1.3 percent higher in this study. Previous cropping and fertilization history
are believed to be the reason for this discrepancy. The planting date study
followed a potato crop in 1990 while the fertility study followed a grain crop
which received less fertilizer in 1990. Petiole nitrate nitrogen contents
were higher at both sampling dates in beets grown following potatoes. High
nitrate nitrogen levels late in the season are known to depress sugar contents.
Petiole nitrogen levels were higher than recommended for all beets
sampled at KES in early September. Beet sugar contents from KES trials were
consistently lower than in local commercial crops. The nitrogen fertilization
program in all trials; 50 lbs N/A preplant and 80 lbs N/A applied in early
July, was apparently excessive. Additional research is required to evaluate
yield and sugar content responses to nitrogen fertilization on mineral soils
in the Klamath Basin.
CONCLUSION
Growers have been using petiole analysis services as a tool to establish
appropriate fertilization practices for this important new crop. Laboratories
providing this service do not have locally derived calibration data to correlate petiole nutrient levels to crop performance. Critical or sufficiency
range nutrient levels are being presented based on crops grown in other
regions and soil types.
A comparison of petiole nutrient levels observed in this study with
critical levels provided by Western Laboratories, Inc. (Parma, Idaho),
suggests beets in this study were deficient in sulfur, calcium, magnesium,
zinc, and copper. Samples from numerous commercial fields have been similarly
diagnosed. The lack of petiole sulfur and calcium level responses to the
application of gypsum, and the high beet yields achieved in this study,
suggest the interpretation of petiole nutrient levels may not be appropriate
for beets produced in the Klamath Basin.
-
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Table 1. Effects of broadcast versus banded starter fertilizer and gypsum on
petiole nutrient levels in HH55 sugarbeets, Klamath Experiment
Station, OR, 1991.
Treatments
Petiole nutrient content
Starter
Fertilizer Gypsum NeN
tons/A
ppm
P
K
S
Ca
Mg
Mn Zn Cu
ppm
August 2
Treatment Main Effects:
Broadcast
Banded
0
1.0
7,600
9,200
0.28
0.29
3.6
3.8
0.09
0.10
0.27
0.27
0.22
0.23
31
43
9
10
3
3
8,400
8,500
0.29
0.28
3.6
3.8
0.09
0.10
0.27
0.27
0.22
0.23
36
39
9
10
3
3
September 4
Treatment Main Effects:
Broadcast
Banded
---
4,000
5,000
0.14
0.20
3.1
2.7
0.10
0.11
0.30
0.27
0.25
0.24
36
38
9
9
3
3
0
1.0
4,800
4,300
0.17
0.17
2.8
3.0
0.10
0.11
0.28
0.28
0.24
0.25
35
39
9
9
3
3
7,600
0.22
2.5
0.20
0.40
0.30
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17
5
Critical level'
1/ As reported by Western Laboratories, Inc. for crop status in early
August.
Table 2. Effects of broadcast versus banded starter fertilizer and gypsum on beet yield, sugar content, and
sugar yield of HH55 sugarbeets, Klamath Experiment
Station, OR, 1991.
Treatment
Fertilizer Gypsum
method
Beet
Beet
population yield
Sugar
Sugar
content yield
tons/A
plants/A
tons/A
%
cwt/A
Broadcast
Broadcast
0
1.0
32,800
33,200
29.1
29.9
17.21
17.08
100
102
Banded
Banded
0
1.0
33,800
33,500
30.6
29.8
17.32
16.89
111
101
---
33,000
33,700
29.5
30.2
17.15
17.11
101
106
0
1.0
33,300
33,300
29.9
29.9
17.27
16.99
106
102
Treatment main effects:
Broadcast
Banded