Phosphorus Q & A

  • What is Phosphorus?
    • Phosphorus is a chemical element with symbol P and atomic number 15. As an element, phosphorus exists in two major forms—white phosphorus and red phosphorus—but because it is highly reactive, phosphorus is never found as a free element on Earth.
  • Why is phosphorus important to plant health?
    • Phosphorus supplies energy to the plant.
    • Photosynthesis cannot happen without it.
    • Moves carbohydrates through the veins of plants
    • Healthy root systems and ample reproduction require proper P levels
  • What does a phosphorus deficient turf look like?
    • The first sign of a phosphorus deficiency is reduced vigor or slowed growth. Visually, the turf may appear somewhat dark green but the area will not seem to be growing as vigorously as expected. As the severity of the deficiency worsens, the appearance may continue to darken and the color of individual leaves may gradually change from dark green to purple as reddish pigments accumulate. The plant will have more shallow root systems, stunted growth and smaller seed-heads.
  • How much Phosphorus should turf grass soil have?
    • Opinions on the desired amount of phosphorus vary. Due to environmental concerns, phosphorus has been banned due to the mineral causing water sources to be filled with harmful bacteria. Portage Turf is looking for a phosphorus level of over 100lbs/acre. Due to the low levels of phosphorus in modern fertilizers over the past decade, most of our lawns are deficient in this element.
  • How can we correct phosphorus deficiencies?
    • Most fertilizers show their phosphorus level in the second number on the label. For instance, 16-2-3 fertilizer has 2% phosphorus. Phosphorus, as an element, is highly combustible and heats up QUICK so it must be added in small amounts and in the right form for plant uptake. Applications with very high phosphorus must be applied responsibly. Starter fertilizers are higher in phosphorus for root development so we apply starter fertilizer to phosphorus deficient lawns.
  • Does applying starter fertilizer really fix phosphorus deficiencies?
    • Hopefully yes, the soil texture and structure and soil acidity (pH) have a great deal to do with the availability and uptake of phosphorus. Sand, silt and clay soils accumulate elements differently and phosphorus can be eroded instead of used by the target plant. This is not an exact science but applying regular responsible applications can greatly improve topsoil health.
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