Q1: Which of the following fertilisers contains the least percentage of nitrogen?

ANS:C - Ammonium phosphate

Ammonium phosphate is a type of nitrogen-phosphorus fertilizer that contains nitrogen in the ammonium (NH4+) form and phosphorus in the phosphate (PO43-) form. It is commonly used in agriculture to provide essential nutrients to plants, particularly nitrogen and phosphorus, which are vital for plant growth and development. Here are some key points about ammonium phosphate:

1. Chemical Composition: Ammonium phosphate refers to a group of fertilizer compounds that contain both ammonium ions (NH4+) and phosphate ions (PO43-). The most common types of ammonium phosphate fertilizers include monoammonium phosphate (MAP), diammonium phosphate (DAP), and ammonium polyphosphate (APP). These compounds vary in their nitrogen and phosphorus content, as well as their solubility characteristics.
2. Nitrogen Source: The nitrogen in ammonium phosphate fertilizers is provided in the form of ammonium ions (NH4+). Ammonium nitrogen is readily available to plants and is gradually released into the soil as ammonium ions undergo microbial conversion to nitrate (NO3-), which is the preferred form of nitrogen for most plants.
3. Phosphorus Source: The phosphorus in ammonium phosphate fertilizers is provided in the form of phosphate ions (PO43-). Phosphorus is essential for various plant processes, including photosynthesis, energy transfer, and root development. Phosphate ions in ammonium phosphate fertilizers are readily available to plants upon dissolution in soil moisture.
4. Solubility and pH: Ammonium phosphate fertilizers are generally water-soluble and can dissolve readily in soil moisture, making the nutrients available for plant uptake. However, the acidic nature of ammonium phosphate fertilizers can lower soil pH over time, which may require additional measures to maintain optimal soil pH for plant growth.
5. Application: Ammonium phosphate fertilizers are typically applied to the soil as granules or prills and can be broadcast, band-applied, or applied through fertigation systems. The application rate depends on various factors, including soil nutrient levels, crop nutrient requirements, and environmental conditions.
6. Crop Use: Ammonium phosphate fertilizers are suitable for a wide range of crops, including cereals, oilseeds, fruits, vegetables, and forages. They are particularly beneficial for crops with high phosphorus requirements during early growth stages or for crops grown in phosphorus-deficient soils.