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Agronomy QUESTION #2062
Question 1
In drip fertigation, urea is preferred over ammonium nitrate for nitrogen supply primarily because:
  • Urea has higher N content (46%) and remains soluble in irrigation water without precipitating or corroding drip emitters under normal conditions✔️
  • Ammonium nitrate is less soluble in water
  • Urea immediately converts to nitrate before entering drip lines
  • Ammonium nitrate causes salt injury to crops when fertigated
Correct Answer Explanation
Urea (46% N) is the most commonly fertigated N source because it is highly soluble (1080 g/L at 20°C), non-ionic (does not react with Ca, Mg, or carbonates in irrigation water to precipitate), and non-corrosive to metal emitters. Ammonium nitrate, while soluble, can react with hard water and poses explosion risk in storage.