Plants absorb 13 minerals from the soil that are essential for healthy growth. Minerals are dissolved by water and absorbed by plant roots. They become available as nutrient content in vegetables and fruit. Soil mineral content determines plant health and plant health supports human health. Essential minerals in the soil are divided into micro-nutrients and macro-nutrients. Nitrogen, phosphorus and potassium are macro-nutrients that are needed in large amounts for plant growth. Secondary macro-nutrients are calcium, magnesium and sulfur.
Nitrogen is the nutrient needed in the largest amounts for healthy plants. It is part of a cell's process of photosynthesis, which means making things with sunlight. Nitrogen is present in soil microbes. Microbes are the tiny living organisms that are in organic matter. Nitrogen also is absorbed in small amounts from the air and is made available to plants by the process called "nitrogen fixation." Bean plants are able to absorb nitrogen from the air and "fix" it in the soil for other plants to use. Nitrogen helps plants grow rapidly and increases the development of seeds, vegetables and fruit.
Phosphorus is an essential nutrient that also helps transfer energy from sunlight to cell formation. It is involved in the formation of all sugars, starches and oils within growing plants. It helps plants withstand stress such as drought. Phosphorus encourages root growth and blossom development in flowers. It is available in soil as decayed organic matter and from sources such as fish meal.
Potassium improves overall plant vigor and disease resistance. Plant cells use it to build proteins and to transfer sunlight into cell energy. It is a "major ion inside every living plant and animal cell" and is "involved in nerve impulses and muscle contraction, including the heart muscle" according to a report on plant minerals by the Government of Alberta. Potassium is supplied to plant root systems by minerals in the soil that are present in decayed organic matter.
Secondary macro-nutrients essential for plant growth are calcium, magnesium and sulfur. Calcium helps plant cells develop strong membrane structure and promotes thick stems. It also helps correct soil acidity. Magnesium is a part of the chlorophyll in all green plants and it is necessary for transfer of energy from sunlight to plant growth. Sulfur stimulates plant growth and seed formation. It is absorbed by plant roots, becomes available as essential food nutrition and is a part of DNA. These three secondary macro-nutrients are absorbed by plants from the organic matter in soil.