N,P,K (Nitrogen, Phosphorus, and Potassium)
Nitrogen, Phosphorus, and Potassium are three macronutrients make up the basis of most organic and non-organic fertilizers.
Nitrogen promotes leafy growth, which is necessary for leafy greens, and some fruits like tomatoes. For most fruits an excess of nitrogen can cause the plant to grow large, but it will not fruit. Nitrogen should also be limited on root crops as it causes bland flavor, uneven nutrient absorption and a strange furriness.
Generally speaking, an excess of nitrogen creates giant vegetables with poor flavor. Soils with low levels of nitrogen not only provide flavorful fruits and vegetables, but also have the highest concentrations of glucosinolates, a natural component found in brassicas (cabbages, cruciferous vegetables, and mustard plants are members of the brassica family).
However, flavor, color, and nutritional quality is not the primary focus of most large-scale vegetable producers. They grow at a volume that allows their produce to be shipped around the country, which means it is important that their plants mature quickly, and that they are all uniform in size to be deemed acceptable to supermarkets. These growers select breeds and fertilizers that contain high levels of nitrogen to support this process. This may mean that vegetables are underdeveloped at the time of shipping, although they are large so that they have an extended shelf life.
Phosphorus is needed for root, blossom and fruit and seed development, so it is very crucial for the continued growth of fruiting plants around the time of blossoming.
Potassium is needed for water retention and cellular integrity, which improves the overall strength and productivity of plants.
There are also numerous micronutrients that are important to keep in balance, just as in the human body. A healthy plant creates healthy food.