Fertilizer

Fertilizer is any material applied to soil or plant surfaces to supply one or more nutrients essential for plant growth. Fertilizers can be organic or inorganic (synthetic). They are used to replenish soil nutrients depleted by crops or leaching and to improve crop yields and quality. The term NPK is common shorthand for the three primary macronutrients: nitrogen (N), phosphorus (P), and potassium (K).

Organic fertilizers include compost, manure, bone meal, blood meal, fish meal, and green manures. Inorganic or synthetic fertilizers include compounds such as urea, ammonium nitrate, monoammonium phosphate, triple superphosphate, potassium chloride, and complex blends.

Fertilizers provide macronutrients (N, P, K) in varying ratios, as well as secondary nutrients (calcium, magnesium, sulfur) and micronutrients (boron, zinc, iron, manganese, copper, molybdenum, chlorine). Fertilizer products are labeled with guaranteed analysis showing nutrient percentages and the weight of the package. Application rates depend on crop needs, soil fertility, and yield targets and are typically based on soil tests.

Application methods include broadcasting, banding, side-dressing, fertigation through irrigation, and foliar feeding. Timing and placement aim to match plant demand while reducing losses. Storage should be dry and sealed to prevent caking and nutrient loss.

Over-application or improper management can cause environmental problems, including nutrient runoff leading to eutrophication of water bodies, nitrate leaching into groundwater, soil acidification in some cases, and nitrous oxide emissions. Practices such as soil testing, split applications, slow-release or coated products, precision agriculture, composting, manure management, cover crops, and crop rotation can mitigate impacts.

Regulation varies by country but commonly includes labeling requirements, recommended application rates, and safety instructions. Fertilizers are typically stored and transported as dry powders or liquids, with attention to moisture and corrosion.