Nutrients other than nitrogen, phosphorus and potassium (NPK) for cereals,
- London : Home-Grown Cereals Authority (HGCA), 1999
- Home-Grown Cereals Authority Research Review No. 41 .
The elements which are essential for plant growth are classified into two groups, according to the relative amounts (kg/ha or g/ha respectively) required by crops: Major nutrients: nitrogen (N), phosphorus (P), potassium (K), sulphur (S), magnesium (Mg), calcium (Ca), and chlorine (Cl) Trace elements or micronutrients: boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn).