Plant nutrition needs at least 14 mineral elements. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulphur (S) are macronutrients, while chlorine (Cl), boron (B), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), nickel (Ni), and molybdenum (Mo) are micronutrients (Mo). These are generally absorbed by plants from soil. Low phytoavailability of important mineral elements and/or the presence of excessive amounts of potentially harmful mineral elements in the soil solution, such as sodium (Na), chlorine (Cl), bromine (B), iron (Fe), manganese (Mn), and aluminium (Al), limit crop production.