Followings are the slow release fertilizers having low water solubility that undergo chemical and/or microbial decomposition when applied to soil.
(A). Urea-formaldehyde
(B). Phenyl phosphorodiamidate (PPDA)
(C). Urea-Z
(D). Crotonylidene diurea
Choose the correct answer from the options given below:
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To identify slow-release options: look for urea-aldehyde condensation polymers, such as Urea-formaldehyde (UF), Isobutylidene diurea (IBDU), and Crotonylidene diurea (CDU). Compounds like PPDA or DCD are inhibitors, not slow-release nutrient sources.
Step 1: Understanding the Concept:
Slow-release fertilizers are synthesized to have low water solubility, allowing them to release plant-available nutrients over an extended period through chemical or microbial breakdown. Step 2: Detailed Explanation:
- Urea-formaldehyde (UF) (A): A condensation product of urea and formaldehyde. It is a classic slow-release fertilizer that relies on soil microbes to mineralize and release nitrogen.
- Phenyl phosphorodiamidate (PPDA) (B): Is a urease inhibitor, not a slow-release fertilizer. It functions by temporarily blocking the urease enzyme to reduce ammonia volatilization losses from urea.
- Urea-Z (C): A specialized urea-acetaldehyde condensation compound designed as a slow-release nitrogen source.
- Crotonylidene diurea (CDU) (D): A slow-release nitrogen fertilizer formed by the reaction of urea with crotonaldehyde, which undergoes gradual chemical hydrolysis and microbial degradation in soil.
- Therefore, (A), (C), and (D) are slow-release fertilizers, while (B) is a metabolic inhibitor. Step 3: Final Answer:
The slow-release fertilizers in the list are (A), (C) and (D) only.
