Question

Which of the following chemical preservatives have been recommended for the minimization of losses of Farm Yard Manure?
(A) Urea
(B) CAN
(C) Single Super Phosphate
(D) Gypsum

• A. (A), (B), (C) and (D) .
• B. (A) and (B) only.
• C. (B) and (C) only.
• D. (C) and (D) only.

Hint:

Mixing Gypsum or SSP at a rate of \( 10 \text{ to } 20 \text{ kg} \) per ton of manure is a standard recommendation to minimize ammonia volatilization losses from animal manure.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
During storage, Farm Yard Manure (FYM) is subject to nutrient losses, particularly nitrogen loss through the volatilization of ammonia (\(\text{NH}_3\)) gas.
Chemical preservatives are applied to manure to stabilize these volatile nitrogen compounds, converting them into stable, non-volatile salts.

Step 3: Detailed Explanation:
Let us evaluate the chemical action of the listed compounds:
- Urea (A) and Calcium Ammonium Nitrate (CAN) (B) are highly soluble nitrogen fertilizers. Adding them to manure increases the total nitrogen content but does not prevent the volatilization of existing ammonia; in fact, urea can accelerate volatilization due to rapid enzymatic hydrolysis.
- Single Super Phosphate (SSP) (C): SSP contains monocalcium phosphate and gypsum. It reacts with volatile ammonium carbonate to form stable, non-volatile ammonium sulfate, preventing gaseous nitrogen loss.
- Gypsum (D): Gypsum (calcium sulfate, \(\text{CaSO}_4 \cdot 2\text{H}_2\text{O}\)) reacts with ammonium carbonate to yield stable, non-volatile ammonium sulfate and insoluble calcium carbonate:
\[ (\text{NH}_4)_2\text{CO}_3 + \text{CaSO}_4 \rightarrow (\text{NH}_4)_2\text{SO}_4 + \text{CaCO}_3 \]
This reaction effectively traps nitrogen in the manure.
Therefore, only Single Super Phosphate and Gypsum are used as chemical preservatives to minimize nitrogen losses.

Step 4: Final Answer:
Single Super Phosphate and Gypsum are the recommended chemical preservatives for minimizing nitrogen loss in FYM.