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Hidden hunger (micronutrient deficiency)

Hidden hunger refers to sub-clinical micronutrient deficiencies in crops and human diets that depress yield, nutritional quality and health outcomes without producing the obvious leaf-symptom or growth-arrest patterns of an acute deficiency. The term applies both to crops growing at sub-optimal micronutrient supply and to populations whose food does not deliver adequate dietary micronutrients.

Identification

Crop hidden hunger appears as a gap between actual and attainable yield even when N-P-K supply is adequate, often with mild chlorosis or unremarkable foliage. Indian soils are widely deficient in zinc, iron, manganese, copper, boron and molybdenum, a pattern that has been documented over decades of soil-test data and is reinforced where N-P-K-only fertilisation has been practised. The most prominent expression in paddy systems is Zinc Deficiency Paddy, known as khaira.

Monitoring and management

ICAR's All India Coordinated Research Project on Micro and Secondary Nutrients monitors soil and plant micronutrient status across states and provides crop- and soil-specific corrective recommendations. Standard correction uses soil application of the deficient micronutrient salt at recommended dose, optionally followed by foliar spray for rapid in-season recovery. Soil pH is a key co-determinant of micronutrient availability and is managed in parallel; see Soil Ph Management. Routine Soil Testing under the Soil Health Card scheme delivers the diagnostic information needed for targeted application.

Adoption context

A parallel response is biofortification: ICAR has released 203 biofortified varieties of rice, wheat, pearl-millet and other crops between 2014 and 2025, enriched in iron, zinc, protein and other nutrients. These varieties partially address hidden hunger by raising the micronutrient content of the harvest itself rather than only of the soil.

Limitations

Hidden hunger is difficult to diagnose without soil and plant testing because the visible cues are subtle. Foliar correction lasts only a few weeks, and soil applications must be repeated as crops mine the added stock. Imbalanced fertiliser regimes remain the principal driver of new deficiencies.

See also: Soil Testing, Soil Ph Management, Zinc Deficiency Paddy, Soil Organic Carbon Management.

References

  1. Micronutrient Deficiency Stress in Soils of India. Springer.
  2. Micronutrient Deficiencies in Crops and Soils in India. Springer.
  3. Quantifying India's Hidden Hunger. Frontiers in Sustainable Food Systems.