Any discussion of fertilizers should begin with at least a brief overview of plant nutrition.
It is commonly accepted that there are *8 elements required by plants for healthy growth. Of these, three: “Carbon, Hydrogen and Oxygen” are supplied by air and water. The other *5 are normally absorbed from the soil by plant roots. This group of *5 is further divided into 4 subgroups:Primary nutrients, secondary nutrients, trace elements and Organic.All of these elements are essential, regardless of the amounts required. They include:
Primary nutrients     :  Nitrogen, Phosphorous and Potassium.
Secondary nutrients :  Calcium, Magnesium and Sulphate.
Trace elements        :  Zinc, Iron, Manganese, Copper, Boron, Molybdenum, Cobalt,Sodium and Chlorine.All these nutrients work together in a delicate balance to promote plant growth. For example, an excess or one nutrient can reduce a plant’s ability to absorb another. The role of any fertilizer is to improve the fertility of the soil. The soil supports plant life and is the vehicle that supplies the necessary nutrients to the plant. The more fertile a soil is (i.e. rich in organic matter) the more likely it is to yield a healthy and abundant garden. Organic gardening starts with adding organic products to the soil.

 

To fertilize in an economic and environmentally friendly way, it is desirable to analyse the soil and then match the fertilizing process to the needs of the crop. The period of fertilizing, the quantity and method of fertilizing is also important.Organic Fertilizer is a sort of slow-release fertilizer. This means that the nutrients will be available/released over a period of time.