Why Do Plants Like Phosphorus?

Purpose

Phosphorus allows the plant to metabolize nutrients into energy. Without phosphorus the plant cannot perform the essential functions of photosynthesis and respiration. Without these functions, the plant does not have energy available to grow, bloom or spread its roots. Phosphorus is also an essential component of DNA, RNA, nucleotides and the cell membrane, so without phosphorus the plant's cells cannot divide to grow or function properly.

The addition of moderate amounts of phosphorus to the soil, depending on the specific needs of the plant, causes rapid growth and profuse flowering of the plant. Each plant has different phosphorus needs, and too much phosphorus is as damaging to the plant as too little. Test the concentration of nutrients and other elements in the soil and adjust the concentrations as needed to create the optimal combination for the specific plants that grow in the area.

When the soil is too rich in phosphorus, the element builds up in the plant body, inhibiting the plant's ability to absorb micronutrients, such as iron and zinc. Plants with too much phosphorus suffer from iron and zinc deficiencies even when the minerals are available in the soil. Both iron and zinc deficiencies cause the youngest leaves on the plants to lighten or yellow in color, and these deficiencies can occur simultaneously. Immediately discontinue phosphorus-containing fertilizer applications to correct the problem and spray liquid solutions of zinc and iron directly on the plant's foliage. Adding the needed nutrients to the soil will not work when the phosphorus in the soil makes the nutrients inaccessible to the plant, but the plant can absorb the nutrients sprayed directly on the foliage.

Phosphorus deficiency causes slow growth because phosphorus is essential for a plant's root and flower development. In the absence of this nutrient, the plant does not have the energy available to perform these basic functions. Purple or dark green leaves and delayed flowering are the first symptoms of a phosphorus deficiency. Severe deficiencies will cause the edges of older leaves to curl and die. Add phosphorus-rich fertilizer, such as a 20-10-20 combination, to correct the deficiency.