मृदा उर्वरता, पादप पोषण एवं उर्वरक

Sulfur concentrations in inorganic fertilizers:

• Single superphosphate (SSP): Contains $16\%\,\text{P}_2\text{O}_5$, $19.5\%\text{ Ca}$, and $12\%\text{ S}$ ($9-12\%$ range) -> Statement (A) is correct.
• Ammonium sulfate ($(\text{NH}_4)_2\text{SO}_4$): Contains $20.6\%\text{ N}$ and $24\%\text{ S}$ (NOT $16\%$) -> Statement (B) is incorrect.
• Potassium sulfate (SOP, $\text{K}_2\text{SO}_4$): Contains $50\%\,\text{K}_2\text{O}$ and $17.5-18\%\text{ S}$ -> Statement (C) is correct.
• Ammonium phosphate sulfate ($20-20-0-15$): Contains $15\%\text{ S}$ -> Statement (D) is correct.

Diammonium phosphate (DAP, $18

\%\text{ N} : 46\%\text{ P}_2\text{O}_5$) is manufactured by reacting anhydrous/liquid ammonia ($\text{NH}_3$) with furnace- or wet-process phosphoric acid ($\text{H}_3\text{PO}_4$) in a two-stage ammoniation reactor: \[ 2\text{NH}_3 + \text{H}_3\text{PO}_4 \longrightarrow (\text{NH}_4)_2\text{HPO}_4 \]

In the Indian nitrogenous fertilizer industry, ammonia synthesis feedstock consumption follows the ranking:

• Natural Gas (B): Over 80-85% of total ammonia/urea capacity (most energy-efficient and dominant).
• Naphtha (A): Historically second largest share (~10-12%), though progressively converted to gas.
• Coal or Coke (C): Small share (e.g., historical plants at Talcher and Ramagundam).
• Electrolysis of water (D): Minimal historical/experimental share (used initially at Nangal before modernization).