A plant needs a number of different chemical elements in order for it to grow and thrive. The most important are:
- Carbon, hydrogen and oxygen - Available from air and water and therefore in plentiful supply
- Nitrogen, phosphorus, potassium (a.k.a. potash) - The three macronutrients and the three elements you find in most packaged fertilizers
- Sulfur, calcium, and magnesium - Secondary nutrients
- Boron, cobalt, copper, iron, manganese, molybdenum and zinc - Micronutrients
The most important of these (the ones that are needed in the largest quantity by a plant) are nitrogen, phosphorus and potassium. Nitrogen, phosphorus and potassium are important because they are necessary for the basic building blocks (things like amino acids, cell membranes and ATP). For example:
- Every amino acid contains nitrogen.
- Every molecule making up every cell's membrane contains phosphorous (the membrane molecules are called phospholipids), and so does every molecule of ATP (the main energy source of all cells).
- Potassium makes up 1 percent to 2 percent of the weight of any plant and, as an ion in cells, is essential to metabolism.
Without nitrogen, phosphorus and potassium, the plant simply cannot grow because it cannot make the pieces it needs.
If any of the macronutrients are missing or hard to obtain from the soil, this will limit the growth rate for the plant. In nature, the nitrogen, phosphorous and potassium often come from the decay of plants that have died. In the case of nitrogen, the recycling of nitrogen from dead to living plants is often the only source of nitrogen in the soil.
To help make plants grow faster, you need to supply the elements that the plants need in readily available forms, and fertilizer is the easiest way to do that. Most fertilizers supply just nitrogen, phosphorus and potassium because the other chemicals are needed in much lower quantities and are generally available in most soils. Nitrogen, phosphorus and potassium availability is the big limit to growth. The numbers on a bag of fertilizer tell you the percentages of available nitrogen, phosphorus and potassium found in the bag. So 12-8-10 fertilizer has 12-percent nitrogen, 8-percent phosphorous and 10-percent potassium. Thus in a 100 kilogram bag, 12 kg is nitrogen, 8 kg is phosphorous and 10 kg is potassium. The other 70 kg has no real value to the plants and is known as ballast.
I use fertilizers quite often while providing garden maintenance services to my clients. In my professional opinion it is a vital part of ensuring that my clients gardens always look great. For more info you can visit A and F Complex Management.