Which one of the following is not used as fertilizer?

Ammonium salts are widely utilized in agriculture as nitrogenous and complex fertilizers. Ammonium nitrate is a common nitrogenous fertilizer often used in mixtures [2]. Ammonium phosphate, including monoammonium and diammonium phosphate (DAP), provides both nitrogen and phosphorus, making it a critical complex fertilizer for root development and crop yield [2]. Ammonium sulphate is one of the oldest and most widely used nitrogen fertilizers, particularly valued for providing sulfur in a plant-available sulphate form [1]. In contrast, ammonium sulphide is a chemical compound primarily used in industrial processes, such as textile manufacturing and photography, but it is not used as a fertilizer due to its toxicity and lack of stability in soil. While ammonium ions are beneficial, the sulphide form is not a standard agricultural nutrient source [3].

Sources

1. [1] https://agritech.tnau.ac.in/agriculture/agri_nutrientmgt_fertilizers.html
2. [2] https://www1.eere.energy.gov/manufacturing/resources/chemicals/pdfs/profile_chap5.pdf
3. [3] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 2: Functions of an Ecosystem > s r n r u l z N ,- / & f . -. : : u ' , \ S ACADEMY * d 6 # . , r '' t u f Y l ' ' J * w { d ) / u Y . / > p. 20