Symptom Identification Key for Nutrient Deficiencies in Soybeans
Plant symptoms can be used to differentiate and identify crop nutrient disorders. Symptoms of nutrient deficiency vary with variety, growing conditions, and plant age. Similar symptoms may be caused by other abiotic or biotic stresses. Use the following key to help identify nutrient disorders observed in Nebraska soybeans and drybeans.
For more information on these and related topics, also check the UNL Extension publication, Nutrient Management for Agronomic Crops in Nebraska, EC155, available online, or in soft cover through your local Extension office.
Select the best descriptor for your plant symptoms. (Photos courtesy of the International Plant Nutrition Institute except as noted.)
A1. | Symptoms appear first or are more severe on older and/or fully expanded leaves. Select B1 or B2 ► | B1. Symptoms are uniform across leaves. Go to D ► |
| B2. Symptoms are localized on leaves. Go to E ► | ||
A2. | Symptoms appear first or are more severe on younger leaves. Select C1 or C2 ► | |
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C1. |
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C2. | Dark green to bluish green leaves, often with interveinal, small lesions; drybean may have marginal chlorosis. | Phosphorus deficiency (no photo available) |
D1. | Pale green plants, pale yellow leading to brown older leaves, veins are not prominent. | Nitrogen deficiency |
D2. |
Pale green plants; interveinal mottling (or interveinal chlorosis in drybean) of older leaves leading to bronze necrosis; green veins. | Zinc deficiency
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E1. | Green plants with chlorosis along the leaf margins - leading to brown interveinal necrosis in soybean; veins stay green. | Potassium deficiency |
E2. |
Pale green plants with interveinal pale yellow mottling of the leaves followed by interveinal necrosis - or necrosis along the underside of the main veins in drybean. | Magnesium deficiency
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F1. | Symptoms are prominent interveinal chlorosis or necrosis; veins are prominent over length of leaf. | Iron deficiency
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F2. |
Pale yellow leaves with mottled interveinal chlorosis leading to dark brown necrosis. | Manganese deficiency |
F3. | Pale green to yellow leaflets without prominent veins or necrosis. | Sulfur deficiency (no photo available) |
(photo by UNL staff)
