Home › MCQs › Agronomy › Question #2063
Back to Questions
Agronomy QUESTION #2063
Question 1
Iron (Fe) deficiency in crops most commonly occurs in:
  • Acidic, waterlogged, sandy soils with low pH
  • Calcareous (high pH, high CaCO₃) soils where Fe³⁺ is precipitated as insoluble Fe(OH)₃ or FeCO₃, making it unavailable despite adequate total soil Fe content✔️
  • Sandy soils with low organic matter in humid tropical climates
  • Highly acidic forest soils with high Al³⁺ saturation
Correct Answer Explanation
Iron deficiency (lime-induced chlorosis) is paradoxical — soils may contain abundant total Fe but at pH > 7.5, Fe³⁺ is precipitated as Fe(OH)₃ and FeCO₃ (solubility product exceeded). Plants, especially Strategy I species, cannot access precipitated Fe. Interveinal chlorosis of young leaves is diagnostic. Foliar FeSO₄ or chelated Fe (EDTA/EDDHA) corrects deficiency.