Which type of N fertilizers should be avoided in paddy crop?

Correct option is A

• Nitrate-based fertilizers (e.g., Calcium Nitrate, Sodium Nitrate, Potassium Nitrate) should be avoided in paddy fields because they are highly soluble and prone to leaching and denitrification in flooded conditions.

• Paddy fields are waterlogged, creating anaerobic conditions that promote the conversion of nitrate (NO₃⁻) into nitrogen gases (N₂, N₂O) through denitrification, leading to loss of nitrogen and reduced efficiency.

• Preferred Nitrogen Fertilizers for Paddy:

  • Ammonium Sulfate (NH₄)₂SO₄

  • Urea (CO(NH₂)₂) – an Amide fertilizer

  • Ammonium Chloride (NH₄Cl)

• Denitrification: In waterlogged soil, nitrate is converted into nitrogen gases (N₂, N₂O) by bacteria, leading to nitrogen loss.

• Nitrogen Use Efficiency (NUE): Ammonium and amide fertilizers provide better nitrogen availability in paddy fields.

• Ammonical (NH₄⁺) fertilizers : These are stable in anaerobic conditions and preferred for paddy. Example: Ammonium sulfate, Ammonium chloride.

• Amide fertilizers : Urea is the most commonly used nitrogen fertilizer in paddy fields as it is hydrolyzed to ammonium in soil.
• Cyanamide Fertilizers: Contain calcium cyanamide (CaCN₂). Used for soil disinfection and weed control,