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Zinc deficiency is the most widespread micronutrient disorder in rice worldwide. It hits early, hits hard, and is easy to miss because symptoms look like water damage or seedling weakness. Common on high-pH, calcareous, sodic, sandy, and continuously flooded soils.

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When rice is most vulnerable

Early - within 2 to 3 weeks of transplanting or seedling establishment. Severe cases kill affected seedlings; moderate cases delay canopy closure by weeks.

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How zinc deficiency shows in satellite data

  • Patchy, low-NDVI zones at early establishment in fields with high-pH, calcareous, or sodic soils - the same zones repeat each season.
  • Canopy closure lags the rest of the field visibly in the first 30 days.
  • Signature overlaps with salinity and submergence patches; separate using soil pH map and depth of standing water (Zn deficiency worsens with deep flooding early on).

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Field symptoms

  • Dusty-brown blotches on older leaves, starting near the leaf midrib
  • Leaves become brittle and bronzed
  • Stunted plants with reduced tillering, uneven in patches across the field
  • Delayed maturity by 1 to 2 weeks in affected patches
  • Severe cases: seedling death within 2 to 4 weeks of transplanting

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Reduce the damage by

  • Dip seedling roots in a 2 to 4% zinc oxide suspension before transplanting - the cheapest and most effective preventive measure.
  • Broadcast zinc sulphate (10 to 25 kg per hectare) as a basal dressing on known Zn-deficient soils.
  • Foliar zinc sulphate (0.5%) at early tillering as a rescue application.
  • Drain the field temporarily on continuously flooded Zn-deficient plots - alternate wetting and drying improves Zn availability.
  • Do not over-apply P on Zn-deficient soils - excess P worsens Zn deficiency.
  • Choose Zn-efficient cultivars where problem is chronic.

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Set an alert for early warning

Turn the diagnosis into a trigger. Go to the Alerts page and configure a rule so patchy establishment on Zn-prone soils is caught in the first 30 days, when foliar rescue still works.
Recommended settings for zinc on rice:
  • NDVI threshold alert at 14 to 21 days after transplanting on known Zn-deficient fields.
  • New Imagery alert during the first 4 weeks so you review patchy establishment as soon as data is available.