What is N-P-K?


What is N-P-K?

The ratio of the three main, necessary nutrients (also known as macronutrients) in organic fertilizer or soil amendments. The ratio refers to the percentage of each prevalent in the fertilizer.

  • N = Nitrogen
  • P = Phosphorus
  • K = Potassium (from English “potash”)

Organic fertilizers come from things that were once alive. An organic N-P-K fertilizer can be slow releasing or quick releasing. Most organic fertilizers are slow release.

They can have quick releasing “labile” nutrients, or slow releasing “recalcitrant” nutrients.

Why are N, P, & K important?

  • Nitrogen
    • Basically: Leaf growth
    • Used in new shoots, buds, and leaves
    • Essential for plant growth.
    • Affects vegetable growth and general health
  • Phosphorus
    • Basically: Root formation, stem growth, and fruiting
    • Important for healthy roots
    • Used more heavily during blooming and seed set
    • Needs a balanced pH to be available to the plant
    • Released through decomposing matter
  • Potassium
    • Basically: Flowering and plant immunity
    • Helps with general health of plant
    • Ties in with fruit formation
    • Assists with disease prevention
    • Helps with chlorophyll prediction
    • Helps create efficient water use for plant
    • Creates quality plants

How to recognize a plant’s needs for these?

  • Nitrogen
    • Lack of:
      • Yellowing of older leaves
      • slowing or stopping of plant growth
    • Excess:
      • extremely fast growth, creating spiny and weak plant
      • dark green leaves
  • Phosphorus
    • Lack of:
      • dull green leaves and purplish stems
      • plant is generally unhealthy, sometimes even yellowing
      • lack of blooming with lush green foliage
  • Potassium
    • Lack of:
      • hard to recognize
      • plants overall sick
        • little fruit
        • yellowing from older branches upwards
        • sickly blooms

What are organic forms of N, P, & K to add to the soil?

  • Nitrogen
    • blood meal
    • fish powder
    • composted manure
    • canola meal
    • various liquid organic fertilizers
  • Phosphorus
    • rock phosphate
    • bone meal
    • various liquid organic fertilizers
      • e.g. fish emulsion
  • Potassium
    • sul-po-mag (sulfate of potash magnesia, quick release)
    • greensand
    • liquid fertilizers
      • e.g. Earth Juice’s Meta-K.







About Parallel Self

Gary is the man! . .. ... who is studying Public Relations, immersed in Environmental Advocacy, loves philosophy, works at Trader Joe's, && is currently scouring the earth in hopes of finding a green thumb. Gary welcomes you to forage through the overgrowth of his mind. =]

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