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Competency Area 4: Nutrient Sources, Analyses, Application Methods

PO 27. Describe the physical form and analysis of each of the following phosphorus sources.

  1. Rock phosphate
  2. Triple superphosphate
  3. Monoammonium phosphate
  4. Diammonium phosphate
  5. Ammonium polyphosphate
  1. Rock phosphate: Ca(H2PO4)2
    • Fertilizer grade: 0-18-0
    • Physical form: solid
    • Generally very insoluble
  2. Triple superphosphate: Ca(H2PO4)2
    • Fertilizer grade: 0-46-0
    • Physical form: solid
    • Acidifying agent
    • Water-soluble
  3. Monoammonium phosphate: NH4H2PO4
    • Fertilizer grade: 11-52-0
    • Physical form: solid
    • Soluble, readily available source of P & N
    • Most common dry P fertilizer in NNY
    • May create an acidic zone around fertilizer granules
  4. Diammonium phosphate: (NH4)2H2PO4
    • Fertilizer grade: 18-46-0
    • Physical form: solid
    • Soluble, readily available source of P & N
    • Initial soil reaction can produce free NH3 (high pH, basic) which can cause seedling injury if too much is placed near the seed
  5. Ammonium polyphosphate: Ca(NH4H2PO4)2
    • Fertilizer grade:  10-34-0 or 11-37-0
    • Physical form: liquid
    • Soluble, readily available source of P and N
    • Popular source for starter fertilizer