NPK fertilisers are widely used in agriculture to enhance plant growth by supplying essential macronutrients: nitrogen (N), phosphorus (P), and potassium (K). These three elements are crucial for various aspects of plant development, and their deficiency can significantly limit crop yields.

Nitrogen (N) is a key component of amino acids, which are the building blocks of proteins. Proteins are essential for all aspects of plant growth, including enzyme production, cell division, and chlorophyll synthesis. Nitrogen promotes healthy leaf growth and a deep green colour. A deficiency in nitrogen results in stunted growth and yellowing of older leaves (chlorosis).

Phosphorus (P) plays a vital role in energy transfer within the plant. It is a key component of ATP (adenosine triphosphate), the primary energy currency of cells. Phosphorus is also essential for root development, flowering, and seed formation. Phosphorus deficiency leads to poor root growth, delayed flowering, and reduced fruit/seed set.

Potassium (K) is involved in regulating water balance within the plant, influencing stomatal opening and closing. It also plays a role in enzyme activation, carbohydrate metabolism, and disease resistance. Potassium deficiency results in weakened stems, scorching of leaf margins, and reduced overall plant vigour.

NPK fertilisers provide these elements in a specific ratio, tailored to the needs of different crops and soil conditions. The NPK ratio indicates the percentage of each nutrient by mass in the fertiliser. For example, a fertiliser with an NPK ratio of 10-10-10 contains 10% nitrogen, 10% phosphorus, and 10% potassium. Understanding the role of each element allows farmers to select the appropriate fertiliser to optimise plant growth and crop yields.

The student's statement is incorrect because NPK fertilisers primarily provide macronutrients – nitrogen (N), phosphorus (P), and potassium (K) – not a wide range of micronutrients. Micronutrients are required in much smaller quantities by plants, but are still essential for various metabolic processes. NPK fertilisers typically do not contain significant amounts of micronutrients like iron, manganese, zinc, or copper.

Nitrogen (N) is essential for the synthesis of proteins, nucleic acids (DNA and RNA), and chlorophyll. It promotes vegetative growth, leading to healthy leaf development and increased biomass. Nitrogen deficiency results in stunted growth and chlorosis (yellowing of leaves).

Phosphorus (P) is crucial for energy transfer within the plant, as it is a component of ATP. It also plays a vital role in root development, flowering, and seed formation. Phosphorus deficiency leads to poor root growth, delayed flowering, and reduced fruit/seed production.

Potassium (K) regulates water balance in the plant by influencing stomatal opening and closing. It also activates enzymes involved in carbohydrate metabolism and enhances disease resistance. Potassium deficiency causes weakened stems, scorching of leaf margins, and reduced overall plant vigour.

In summary, while micronutrients are important, NPK fertilisers are specifically designed to provide the three macronutrients – nitrogen, phosphorus, and potassium – that are required in the largest quantities for optimal plant growth and development.

Plants require essential nutrients for healthy growth, and ammonium salts (e.g., ammonium nitrate, ammonium sulfate) and nitrates (e.g., potassium nitrate) provide key elements for this. Plants absorb nitrogen in the form of ammonium ions (NH₄⁺) and nitrate ions (NO₃^-) from the soil.

Nitrogen is a crucial component of amino acids, proteins, nucleic acids (DNA and RNA), and chlorophyll. It's essential for building plant tissues and promoting vegetative growth (leaves and stems). A deficiency in nitrogen leads to stunted growth and yellowing of leaves (chlorosis).

Ammonium salts provide a readily available source of nitrogen. The ammonium ion (NH₄⁺) can be directly assimilated by plants. However, soil conditions (pH) can affect the availability of ammonium. In alkaline soils, ammonium can be lost as ammonia gas (NH₃), reducing its effectiveness. Nitrates are generally more stable in alkaline conditions.

Nitrates are also readily absorbed by plants and are converted to ammonium ions within the plant. They are particularly important for rapid growth and the development of green foliage.

Therefore, the use of ammonium salts and nitrates as fertilizers ensures plants have an adequate supply of nitrogen, promoting healthy growth and increased crop yields.