NPK

NPK refers to the three primary macronutrients essential for plant growth: nitrogen (N), phosphorus (P), and potassium (K). In commercial fertilizers, products are labeled with three numbers representing the percentage by weight of each nutrient, such as 10-10-10 or 20-20-20. These figures indicate the relative abundance of N, P, and K in the formulation.

Nitrogen promotes vegetative growth and foliage, phosphorus supports root development, energy transfer, and flowering, and potassium enhances overall vigor, water regulation, and disease resistance. Plants absorb these nutrients from the soil solution as ions: nitrate or ammonium forms for nitrogen, phosphate for phosphorus, and potassium ions for potassium. The availability of these nutrients is influenced by soil pH, organic matter, and other chemical conditions.

Fertilizers can be tailored to crop needs. Balanced formulations (equal or near-equal NPK) suit general growth, high-nitrogen blends favor leafy crops, high-phosphorus blends support root systems and flowering, and high-potassium blends assist fruiting and stress tolerance. Applications can be granular, liquid, or slow-release, and timing depends on species, growth stage, and environmental conditions. Soil testing or plant tissue analysis helps determine nutrient requirements and minimizes waste.

Common concerns include overfertilization, which can cause salt burn, nutrient lockout, or environmental issues such as nitrate leaching and runoff. NPK fertilizers are widely used in farming and gardening, often complemented by secondary nutrients (calcium, magnesium, sulfur) and micronutrients to address specific deficiencies.