Soil nutrient deficiencies show up as distinct visual symptoms on plant leaves and stems. Early identification lets you apply corrective treatments before yield loss becomes severe. This guide maps observable symptoms to likely deficiencies, with confirmation tests and correction options.
Symptom Identifier
Possible Deficiencies
Quick Reference: Nutrient Mobility and Symptom Location
| Nutrient | Mobility | Symptom Location | Key Symptom |
|---|---|---|---|
| Nitrogen (N) | Mobile | Old leaves first | V-shaped yellowing from tip |
| Phosphorus (P) | Mobile | Old leaves/whole plant | Purple/red discoloration |
| Potassium (K) | Mobile | Old leaf margins | Scorched brown margins |
| Sulfur (S) | Immobile | New leaves first | Uniform yellowing on young leaves |
| Iron (Fe) | Immobile | New leaves | Interveinal chlorosis (veins stay green) |
| Manganese (Mn) | Immobile | New leaves | Interveinal chlorosis, grayish-green |
| Zinc (Zn) | Immobile | New/young leaves | White striping (corn), stunted |
| Magnesium (Mg) | Mobile | Old leaves | Interveinal on older leaves |
How to Use the Soil Nutrient Deficiency Guide
Visual nutrient deficiency diagnosis requires observing both the type of symptom and where on the plant it appears. The mobility concept — whether the plant can move a nutrient from old leaves to new growth — is the most important diagnostic tool available.
Mobile vs. Immobile Nutrients
Mobile nutrients (N, P, K, Mg, S) can be relocated from older leaves to actively growing tissue when deficient. Deficiency symptoms appear on older leaves first. Immobile nutrients (Fe, Mn, Zn, Cu, B, Ca) cannot be relocated, so deficiency symptoms appear on young, actively growing tissue first. This single observation dramatically narrows the list of suspects.
Confirming a Visual Diagnosis
Visual symptoms suggest deficiencies but do not confirm them. Always collect soil samples and plant tissue samples to confirm before making expensive applications. Send samples to a certified lab — most university extension services offer testing for $15-25/sample. A misdiagnosed zinc deficiency treated with iron EDDHA wastes money and could cause imbalances.
Correction Timing
Early vegetative stages (V2-V8 for corn) allow time for soil-applied corrections to work. After V10, foliar applications are more effective for immediate impact. For micronutrient deficiencies (Fe, Zn, Mn), chelated foliar forms are faster-acting than soil applications. Always apply foliar nutrients in the evening or overcast conditions to avoid burn.
FAQ
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What causes yellowing (chlorosis) in corn leaves?
Yellowing in corn can indicate nitrogen deficiency (V-shaped yellow from leaf tip on lower leaves), sulfur deficiency (striping on newer leaves), iron deficiency (interveinal chlorosis on upper leaves), or magnesium deficiency (interveinal on lower leaves). The pattern and location of yellowing points to the specific nutrient. Soil and tissue testing confirms the diagnosis.
How do I tell nitrogen from sulfur deficiency in corn?
Nitrogen deficiency shows V-shaped yellowing starting at the leaf tip on the oldest (lower) leaves first — nitrogen is mobile in plants so it moves from old to new growth. Sulfur deficiency shows striping on the newest (upper) leaves — sulfur is immobile so newer growth is affected first. Location on the plant is the key diagnostic clue.
What is the fastest way to fix a nutrient deficiency mid-season?
Foliar applications of the deficient nutrient can provide rapid correction (2-5 days response). Urea (foliar N) at 4-6 lbs/acre in 20+ gallons water is common for mid-season N topdress. Sulfur applications respond well to foliar AMS. Iron EDDHA chelate applied to soil provides slower but more lasting correction. Confirm deficiency before applying to avoid over-application.
When should I do a tissue test vs a soil test?
Soil tests before planting identify nutrients that need to be built up. Tissue testing during the growing season (V6-V10 for corn) diagnoses current crop nutrient status in real time. Tissue testing is more actionable mid-season because it reflects what the plant is actually absorbing, not just what is in the soil.