Fertilizer 101

Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to the soil to supply elements necessary for the growth of plants. Organic means something that is or was alive. Animal manures were once living plants, bonemeal is composed of ground up bones of animals. Inorganic means from non-living sources, rock phosphate, a common source of phosphorus, comes from rocks, a non-living material. The term natural describes the manure, bonemeal and rock phosphate as all are naturally occurring. The term synthetic describes such products as nitrogen fertilizer which is manufactured. Inorganic fertilizer is immediately available to plants, whereas organic fertilizer must be converted by micro-organisms in the soil to an inorganic form before it can be used. It makes little difference to the plant whether fertilizer is supplied to it as an organic, inorganic, natural or synthetic application as long as adequate amounts are available. Organic sources are usually more forgiving if too much is applied. What The Numbers Mean On a package of fertilizer you will find three or four numbers separated by hyphens. The numbers indicate the percentage of nitrogen (N), phosphorus (P), potassium (K), and sulfur(S). A "complete" fertilizer contains nitrogen, phosphorus and potassium. In addition to these major nutrients there are also trace elements such as iron, zinc, copper, calcium, manganese and magnesium which are necessary for plants to complete there life cycle. What They Do Nitrogen Nitrogen is required for the green, leafy vegetative growth of plants. Deficiency symptoms of nitrogen are an overall pale yellow colour of leaves and dwarfed or stunted plants.   Nitrogen is easily leached down through the soil below the roots and is not available to the plant so is the element most often lacking and needing replacement. Too much nitrogen can delay flowering, fruiting and seed set. Phosphorus Phosphorus promotes root growth, root branching, stem growth, flowering, fruiting, seed formation and maturation. Deficiency symptoms are indicated by a red or purplish tinge to stems and foliage. It is stable and non-mobile in the soil so leaching is not a problem. Potassium Potassium enables the plant to withstand stress such as drought, cold, heat, and disease. It also stimulates flower colour and promotes tuber formation and a strong root system. Deficiency symptoms are indicated when the leaves appear dry and scorched on the edges and have irregular yellowing. Sulfur Sulfur is essential to plant growth and metabolism. Deficiency symptoms are indicated by stunted, thin-stemmed, and spindly plants. Fruit and seed maturity may be delayed when sulfur is lacking.