N : Nitrogen = Stimulates growth
P : Phosphros = Enhances seed and friut formation
K : Potassium = Strenghens stems, increases root growth and helps in the setting of fruit.
A properly developed compost is a complete plant food.
Phosphorus (P) is a vital element in all biological energy transfer systems, such as the conversion of solar energy into chemical energy with the formation of chlorophyll and glucose. It encourages fruit development and fertility of resultant seed.
Bones and other skeletal material, such as prawn shells, are rich in phosphorus. Other
sources are animal manure such as seabirds and bats. Earthworm casts are also rich in phosphorus.
Potassium is a major plant nutrient in the form of potash (K2O). Potassium is contained in most organic materials, although wood-ash, soot and seaweed, are richer than others.
Other potassium rich minerals are granite and basalt rock flours
Chemical fertilizers usually contain potassium chloride. Such potassium salts are so readily soluble that they may cause the plant to absorb excess potash which can inhibit assimilation of other nutrients, such as phosphorus. This problem does not happen in organic sources as the intake of nutrients by the plant is both slower and more balanced.
.pH = power of hydrogen
It is the relationship between hydrogen ions (H+) and hydroxyl ions (OH-). The more hydrogen ions the greater the acidity 1-6 pH. The more dominant in alkaline environments 8-14 pH.
The optimum pH for the majority of common plants is between 6.5 and 7 pH.