Sorghum Fertility

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Sorghum Fertility

• Brian ArnallOklahoma State UniversityDept Plant
  and Soil Sciences

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Outline

• Nitrogen
• Phosphorous
• Potassium
• pH
• Micros

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Soil Testing

• OSU, Ward, ect. 10 - 15
• 20 lb N 9
• 20 lb P 7.2
• ¼ Ton Lime 5-10
• Per Acre!!!!!
• Some Co-Ops and Fertilizer Dealers,
• Take and Process samples for FREE!!!!!!

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Nitrogen

• Determined by Yield Level

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Strips and Sensors
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Phosphorous

• Independent of Yield

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Potassium

• Independent of Yield

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Variability
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pH Issues
Mixed Reports, some state more Al tolerant and
others show less.
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Micronutrients Needed by all Crops
Nutrient
Iron
Manganese
Copper
Zinc
Boron
Chlorine
Molybdenum
Soil (lb/a)
14,000 1,100,000
40 6,000
4 - 200
20 - 600
4 - 200
40 1,800
0.4 - 10
Crop (lb/a)
1
0.8
0.08
0.6
0.08
4
0.0008
Range of total in soils. From Chemical
Equilibria in Soils. W.L.Lindsay, 1979. Wiley
Sons.
Calculated for 2 ton crop yield (67 bushel
wheat).
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Nutrients not found deficient in Oklahoma crops.

• Calcium.
• Liming prevents Ca deficiency.
• Manganese.
• Copper.
• Molybdenum.

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Nutrients seldom found deficient in Oklahoma
crops.

• Magnesium.
• Sulfur.
• Iron.
• Zinc.
• Boron.
• Chlorine.

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MgYellowing between veins, old leaves
Dolomitic Lime Sul-po-Mag, K-Mag
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SulfurCan look like N, Yellowing between
veinsGyp, S, Ammon Sulfate
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IronYellowing between veins, new leavesFerrous
Sulfate, ect
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Micro Nutrients

• Zinc, Bronze between Margin and Midrib. Bleaching
  on either side of Midrib Zinc Sulfate, Zinc
  Chloride, Zinc Chelate
• Boron, Borax
• Chloride, Upper Leave Wilt,Muriate of
  Potashwhich K is usually also deficient

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Soil Testing
Just Do It!
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Thank You!

• Corn and Sorghum Nutrient Need Petes Sheets
  coming soon