Fertilizer adds nutrients to soil to help plants grow. The main nutrients are nitrogen, phosphorus, and potassium. Plants need them in large amounts. Soils often lack one or more. Farmers apply fertilizer to boost yields. Without it, global food production would fall sharply.

There are two broad types. Organic fertilizers come from plant or animal matter: manure, compost, bone meal. They release nutrients slowly and improve soil structure. Synthetic fertilizers are manufactured, often from natural gas and mined minerals. They are concentrated and fast-acting. Most modern agriculture relies on synthetics.

The benefits come with costs. Excess fertilizer runs off fields into waterways, causing algal blooms and dead zones. Nitrogen fertilizer produces nitrous oxide, a potent greenhouse gas. Phosphate rock is a finite resource, concentrated in a few countries. Precision application, cover crops, and slow-release formulas can reduce waste. The challenge is feeding the world without poisoning the water.

Main nutrients

• Nitrogen (N)
• Phosphorus (P)
• Potassium (K)
• Secondary nutrients: calcium, magnesium, sulfur
• Micronutrients: iron, zinc, boron