The Elements of Complete Plant Nutrition: Essential Macronutrients

The following is a brief summary of the role of essential and beneficial mineral nutrients crucial to plant growth. If any one of the essential elements is eliminated from a plantís nutrition, it will display abnormalities of growth, symptoms of deficiency, and may not reproduce normally.

Essential Macronutrients:

Nitrogen is a major component of proteins, hormones, chlorophyll, vitamins, nucleic acids. Nitrogen metabolism is a major factor in stem and leaf growth (vegetative growth). Over applications of nitrogen will be detrimental to growth. Deficiencies can reduce yields, cause yellowing of the leaves and stunt growth.

Phosphorus is necessary for seed germination, photosynthesis, protein synthesis and almost all aspects of growth and metabolism in plants. Phosphorus is a component of RNA and DNA, the genetic makeup of life. It is essential for flower and fruit formation. Low pH (<4) results in phosphate being chemically locked up in organic soils. Deficiency symptoms include stunted growth are dark green leaves. Purple coloring may also appear due to anthocyanin accumulation.

Potassium is an activator of many enzymes that are required in photosynthesis and respiration. It is involved in osmotic potential in cells. Potassium is also required for protein synthesis and phloem transport.

Sulfur is a structural component in proteins and vitamins. Sulfur is essential in respiration and lipid metabolism. It imparts flavor to many vegetables. Deficiency symptoms appear as chlorosis throughout the leaves, but sulfur deficiencies are rarely encountered. Sulfur is readily lost by leaching from soils and should be applied with a nutrient formula. Many water supplies contain sulfur.

Magnesium is a critical structural component of the chlorophyll molecule and is necessary for functioning and/or activation of plant enzymes to produce carbohydrates, sugars, proteins, and fats. It is used for fruit and nut formation and is essential for germination of seeds. In essence, magnesium is essential to every metabolic pathway in plants. Deficient plants appear chlorotic, show yellowing between veins of older leaves; leaves may droop. Magnesium is leached by watering and must be supplied when feeding. It can be applied as a foliar spray to correct deficiencies.

Calcium activates enzymes, is a structural component of cell walls, influences water movement in cells and is necessary for cell growth and division. Calcium is required for membrane function in all cells. Some plants must have calcium to take up nitrogen and other minerals. Calcium is easily leached. Calcium, once deposited in plant tissue, is immobile (non-translocatable), so there must be a constant supply for growth. Deficiency causes stunting of new growth in stems, flowers and roots. Symptoms range from distorted new growth to black spots on leaves and fruit.

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