current status of soil test calibration in mississippi
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Current Status of Soil Test Calibration in Mississippi. Bobby R. Golden Delta Research and Extension Center 479-409-6191 [email protected] Mississippi-crops.com. Updating Soil Test C orrelations in MS. Why are we interested in doing this ? Changing crop rotational mix - PowerPoint PPT PresentationTRANSCRIPT
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Current Status of Soil Test Calibration in Mississippi
Bobby R. GoldenDelta Research and Extension Center
Mississippi-crops.com
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Updating Soil Test Correlations in MS
• Why are we interested in doing this ?
• Changing crop rotational mix
• Improved production practices since last major update
Lancaster unpublished data (19?)
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Interpretation of Soil Test Results
• A soil-test value is an INDEX, is not “the” total amount available (snapshot in time)
• Field calibrations with crop response give a meaning to soil-test values by different testing methods.– critical/optimum value or range– interpretation classes– application rate for responsive ranges
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How do we get there ?
• Program Development for Correlation/Calibration
• Currently working on Corn, Soybeans, and Cotton.
• P, K, Zn• Major Goal:
– Field correlate soil test index to yield response and tissue concentrations
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Potassium and Corn• Soil test K in the top 6”
of soil is an indicator of corn yield responsiveness in the Midwest.
• Does this hold true for the Midsouth?
• However corn is new to the Midsouth and little research has been conducted to establish critical values
0 lb K2O/acre
160 lb K2O/acre
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Corn Response to K Fertilization
Leflore Co
Potash rate (lb K2O/acre)
0 40 80 120 160 200
Mean corn grain yield (bu/acre)
100
150
200
250 Bolivar Co.
Potash rate (lb K2O/acre)
0 40 80 120 160 200
Mean corn grain yield (bu/acre)
100
150
200
250
Golden unpublished data (2012)
73 bu/ac yield response 27 bu/ac yield response
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Corn Response to K Fertilization
Lancaster Soil Test K
Lancaster extractable K (ppm)
0 50 100 150 200 250 300 350
Relative corn yield (%
)
50
60
70
80
90
100
110
Non ResponsiveResponsive
Mehlich-3 Soil Test K
Mehlich-3 extractable K (ppm)
0 50 100 150 200 250 300 350
Relative corn yield (%
)
50
60
70
80
90
100
110
Non ResponsiveResponsive
Golden unpublished data (2012)
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Potassium and Soybean
• Soil-test K in the top 4 or 6 inches of soil is an excellent predictor of soybean responsiveness to K fertilization.• Slaton et al. 2010• Mallarino et al., 2005• Clover and Mallarino, 2009
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Soybean Actual Yield at Responsive sites
Golden unpublished data (2012)
Responsive sites
K fertilizer rate (lbs K2O/acre)
0 40 80 120 160 200
Soybean yield (bu/acre)
40
50
60
70
80
90
100Humpherys CoBolivar Co
10 bu/ac response8 bu/ac response
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Soybean Yield Response to K Fertilization
Lancaster Soil Test K
Lancaster extractable K (ppm)
50 100 150 200 250 300 350
Relative soybean yield (%
)
0
20
40
60
80
100
120
Non Responsive SitesResponsive Sites
Mehlich-3 Soil Test K
Mehlich-3 extractable K (ppm)
50 100 150 200 250 300 350
Relative soybean yield (%
)
0
20
40
60
80
100
120
Non ResponsiveResponsive
Golden unpublished data (2012)
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Soybean Tissue Response to K Fertilization
Lancaster Extractable K (ppm)
50 100 150 200 250 300 350
Soyb
ean
Tiss
ue K
@ R
2 (%
)
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3Non Responsive SitesResponsive Sites
Mehlich-3 Extractable K (ppm)
50 100 150 200 250 300 350
Soyb
ean
Tiss
ue K
@ R
2(%
)
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3Non Resonsive SitesResponsive sites
Golden unpublished data (2012)
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Mehlich 3 - Lancaster Correlation
Lancaster Extractable K (ppm)
0 100 200 300 400 500
Meh
lich-
3 Ex
trac
tabl
e K
(ppm
)
0
100
200
300
400
500
600M3K = 4.102 + 0.9547(lancaster K)
Golden unpublished data (2012)
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Mehlich 3 – Lancaster Correlation
M3P = -10.149+0.8140(lancaster)
Lancaster Extractable P (ppm)
0 20 40 60 80 100 120 140 160
Meh
lich
3 Ex
trac
tabl
e P
(ppm
)
-20
0
20
40
60
80
100
120
140
Golden unpublished data (2012)
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Zinc Deficiency Symptomology
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Methods of Zn Fertilization• Soil Applied
– 10 lb Zn/acre as a granular fertilizer
– Adjust rates based on water solubility of Zn sources
• Foliar Applied– Apply 1-2 lb Zn/acre after
emergence– Chelated for soil
application (Little foliage for interception)
– Sulfate for foliar application (larger plants)
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Zinc Rate Response Trials 2012
Zn application rate (lb Zn/acre)
0 2.5 5 7.5 10
Mean corn grain yield (bu/acre)
0
50
100
150
200
250
300Bolivar Co (29 bu increase) DREC7 (16 bu increase)
Corn Response to Zn Rate
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Lancaster Extractable Zn (ppm)
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Rela
tive
Cor
n G
rain
Yie
ld (%
)
86
88
90
92
94
96
98
100Responsive SitesNon Responsive Sites
Mehlich-3 Extractable Zn (ppm)
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Rela
tive
Cor
n G
rain
Yie
ld (%
)
86
88
90
92
94
96
98
100Responsive SitesNon Responsive Sites
Corn Yield Response to Zn Fertilization
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M3Zn=0.4914 +1.44(lancaster)
Lancaster Extractable Zn (ppm)
0 2 4 6
Meh
lich
3 Ex
tract
able
Zn
(ppm
)
0
2
4
6
8
10
Mehlich 3 - Lancaster Correlation
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Zn Product Foliar Burn
EDTA Chelate @ 2lb ZnCitric Acid Chelate @ 2lb Zn
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Zinc Product Foliar Burn @ 6d after application
Zn application rate (lb Zn ac-1)
0.5 1 2
Visual Injury Rating (%
)
0
10
20
30
40
50
60
70EDTA ChelatedCitrate Chelated
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Zinc Foliar Burn - Tissue Concentration @ 2 WAA
Zn application rate (lbs Zn acre-1)
0.5 1 2Corn leaf tissue Zn concentration (ppm
)
0
20
40
60
80
100
120
140Main effect of Zn rate (p =<0.0001)
Golden unpublished data (2012)
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Zinc Foliar Burn Tissue Concentration @ 2 WAA
Zn Product
Citrate EDTA
Cor
n Le
af T
issu
e Zn
Con
cent
ratio
n (p
pm)
0
20
40
60
80
100
120 Main effect of Zn product (p=0.0091)
Golden unpublished data (2012)
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Zn Foliar Burn Grain Yield
Zn Rate (lb Zn/acre)
0.5 1 2
Mean corn grain yield (bu/acre)
0
50
100
150
200
250
300EDTA ChelateCitric Acid Chelate
Golden unpublished data (2012)
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Zinc Basics
• Soil test Zn coupled with pH is a good indicator of need
• Use the Right rate for the Zn source and soil
• Remember not all Zn fertilizers are created equal– Must take into account water solubility– Supply Zn early
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At the End of the Day• Fertilizer costs money,
but yield pays the bills: High fixed production costs for land, good seed, equipment– relative costs, and
business management approach