In the past, fertilisers were described using a wide variety of unrelated product names, such as ‘Super Potash 3 & 1’, ‘Starter 15’ and ‘Legume Special’. Application rates were given as the amount of the product (eg 375 kg/ha of 3 & 1). These names did not give any information about the amounts of nutrients (eg nitrogen, potassium) being applied. In recent years, fertiliser names have been changed to convey their nutrient concentrations. Application rates are usually given as the amount of a specific nutrient per hectare (eg 50 kg P/ha) and may or may not include the amount of the actual fertiliser product.

The United Kingdom, and the Food and Agriculture Organization of the United Nations refer to concentrations of fertiliser components in terms of the oxide form: phosphate (P₂O₅), potash (K₂O), sulfur trioxide (SO₃), magnesium oxide or magnesia (MgO) and sodium oxide (Na₂O). In Australia, however, these components are referred to as elements (eg N, P, K, S). Set the capital letter abbreviations solid and without punctuation:

The nutrient concentrations of elements are listed in the order N, P, K, S. They can be separated by either hyphens or colons (hyphens are preferable for readability). For example, a fertiliser containing 12% nitrogen, 32% phosphorus and 16% potassium can be written as:

For solid fertilisers, concentrations are usually stated either on a weight-for-weight basis (eg 35% wt/wt or 35 g/kg) or, for liquid fertilisers, on a weight-for-volume basis (eg 3.5% wt/vol or 35 g/L).