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Zinc Deficiency

Zincum Deficientia

Basic Details

Description

Nutrient Info

Identify

Seasonal Calendar

Treatment

FAQs

How to Identify Zinc Deficiency on Rice (Paddy)

Zinc Deficiency identification guide illustration

Visible Symptoms

Dusty brown spots or blotches appearing on older leaves 2-4 weeks after transplanting. The midribs turn yellow, and leaves become brittle. Affected crops remain severely stunted and grow unevenly.

Key Identification Checklist for Rice Zinc Deficiency (Khaira Disease): 1. Dusty, Reddish-Brown / Bronze Blotches at 2–3 Weeks After Transplanting: Symptoms appear during active tillering (15–25 DAT) on older lower leaves as tiny chlorotic spots that rapidly turn rusty copper-brown or bronze. 2. Coalescing Rusty Leaf Lesions ('Burnt' Field Appearance): The bronze blotches coalesce across the leaf blade between the green veins, making the entire lower canopy look scorched, rusted, or burnt. 3. Dark Brown, Stunted, Decaying Root System: When affected hills are pulled up from the mud, roots are short, sparse, dark brown to black, and lack white, active feeder root tips. 4. Severe Stunting & Uneven Canopy Growth: Affected patches in the field stop tillering and remain severely dwarfed, while higher, less waterlogged areas appear greener, creating an uneven, wavy crop height across the paddy.

About Zinc Deficiency

NameZinc Deficiency

Description

Zinc deficiency, historically known across South Asia as Khaira Disease, is the most widespread micronutrient disorder in wetland rice. Continuous soil submergence and high pH immobilize zinc into insoluble zinc sulfide and hydroxide forms, causing rusty-brown leaf blotching and stunted growth 2-4 weeks after transplanting.

TypeDeficiency

Severity Level Severe

Nutrient Role & Deficiency Cause

Affected Growth Stages

Early VegetativeTillering

Why It Happens

Also Known AsKhaira disease of rice, Zn starvation, rusty leaf spot of paddy

Seasonal Outbreak Calendar

Outbreak risk and activity timeline for Zinc Deficiency based on seasonal climate patterns:

Active Window:July - October

Peak Outbreak:July - September

Critical Crop Stage:Early Tillering Stage (15-30 DAT in submerged soil)

JanLow Risk

FebLow Risk

MarLow Risk

AprLow Risk

MayLow Risk

JunLow Risk

JulPeak Risk

AugPeak Risk

SepPeak Risk

OctModerate

NovLow Risk

DecLow Risk

Low Outbreak Risk

Active / Moderate Risk

High Risk / Peak Outbreak

Want to see this disease and others mapped across other regions? View Global Outbreak Calendar

Treatment & Correction Guide

Natural & Organic Methods

Mid-Season Drainage and Soil Aeration

Drain standing water for 4–5 days until soil surface develops fine hairline cracks Implement at first symptom onset (2–3 weeks after transplanting) Re-oxidizes soil, converts insoluble sulfides to sulfates, and releases native zinc within 5–7 days

Zinc-Enriched Farmyard Manure Incubated Compost

10 kg Zinc Sulfate incubated with 500 kg moist cattle manure for 30 days; broadcast per acre Applied during final puddling before transplanting Prevents zinc fixation in calcareous soils, sustaining available Zn throughout tillering

Green Manuring with Sesbania aculeata

8–10 tons green biomass incorporated before flooding Basal pre-transplanting green manuring Organic acids from decomposition mobilize native soil zinc

Chemical & Professional Control

Zinc Sulfate Heptahydrate (ZnSO4 · 7H2O, 21% Zn) Soil Basal Application

10–12 kg/acre (or 25 kg/ha) broadcast at final puddling Single basal application before transplanting (effective for 2–3 consecutive crops) Completely prevents Khaira disease and promotes vigorous tillering

Zinc Sulfate Monohydrate (ZnSO4 · H2O, 33% Zn) Soil Application

6–7 kg/acre broadcast before final puddling Single basal application Higher concentration, rapidly water-soluble zinc source

Emergency Foliar Zinc Spray (ZnSO4 + Slaked Lime / Urea)

5 g Zinc Sulfate (21%) + 2.5 g slaked lime (or 10 g Urea) per Liter water (1 kg ZnSO4 + 0.5 kg lime in 200L/acre) 2 sprays at 7-day intervals starting at first appearance of rusty bronze spots Dramatic greening of newly emerged leaves within 4–6 days; active tillering resumes

Chelated Zinc (Zn-EDTA 12%) Foliar Spray

1.0 g per Liter water (200 g in 200L/acre) 2 sprays at 7–10 day intervals Fastest cuticular penetration without risk of leaf scorching

Frequently Asked Questions

What is Khaira disease in rice, and why does it occur 2 to 3 weeks after transplanting?

First discovered by Dr. Y.L. Nene in 1966 at Pantnagar, Khaira is nutritional zinc starvation in wetland rice. It manifests 2 to 3 weeks after transplanting because early seedling zinc reserves are exhausted, while prolonged submerged anaerobic conditions in the paddy produce bicarbonates and sulfides that precipitate soil zinc into unabsorbable forms.

Why must slaked lime or urea always be mixed with Zinc Sulfate foliar spray in rice?

Zinc sulfate heptahydrate dissolves into an acidic solution (pH ~4.5). Spraying it unbuffered causes severe leaf burning (acid scorch) on delicate rice foliage. Adding 0.25% slaked lime (calcium hydroxide) or 1% urea neutralizes the spray solution and accelerates cuticular zinc absorption.

Why does temporarily draining a flooded paddy field help cure zinc deficiency?

Draining standing water allows atmospheric oxygen to penetrate the root zone, re-oxidizing the reduced soil. This breaks down toxic hydrogen sulfide (H2S) into soluble sulfate and liberates bound zinc ions for root uptake within 5 to 7 days.

Can I apply Zinc Sulfate together with DAP or SSP fertilizer?

NEVER mix zinc sulfate directly with phosphatic fertilizers (DAP or SSP). Water-soluble phosphate reacts instantly with zinc cations to form insoluble Zinc Phosphate (Zn3(PO4)2), rendering both phosphorus and zinc completely unavailable to rice roots.

What soil types are most prone to Khaira zinc deficiency?

Calcareous soils with high free calcium carbonate (CaCO3), alkali/sodic soils (pH > 8.0), continuously submerged waterlogged lowlands, and light sandy soils depleted of organic matter are most susceptible to severe zinc deficiency.

Remedy Disclaimer & Safety Notice

This disease guide is for educational screening purposes only. Pathogen behavior, severity, and host susceptibility can vary dramatically based on seed variety, weather conditions, and regional microclimates. Chemical pesticides and organic treatments are subject to strict regional environmental regulations and registration mandates. Please verify all chemical registrations and review manufacturer safety labels carefully with local certified agronomists or agricultural extension service offices before applying.

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