Any discussion about fertilizers should begin with at least a brief overview of plant nutrition. There are 16 elements required by plants for healthy growth. Of these, three are supplied by air and water-carbon, hydrogen and oxygen.
The other 13 are divided into three subgroups: primary nutrients, nitrogen, phosphorous and potassium; secondary nutrients, calcium, magnesium and sulfur; and micro-nutrients, zinc, iron, manganese, copper, boron, molybdenum and chlorine. All of these elements are essential regardless of the amounts required.
