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Competency Area 4: Nutrient Sources, Analyses, Application Methods

PO 31. Define the following nutrient terms.

  1. Total Kjeldahl Nitrogen (TKN)
  2. Organic N
  3. Inorganic N
  4. Organic P
  5. Inorganic P
  6. Dissolved P
  7. Particulate P

Total Kjeldahl Nitrogen is the total N analytical method that determines the organic and ammonium N fraction in soils, plants, and waters.  Soils range from 0.05 to 0.3% typically, but can be much higher for mucks.  Plants are normally 0.2 to 4% depending on species, age, plant part, etc.

Organic N is the nitrogen fraction that is organically-bound (i.e. protein).  Organic N is not water-soluble and is slow to become available.  Most manure and biosolid N is organically-bound, and must undergo mineralization before it can be used by plants.

Inorganic N is not organically-bound; for instance, ammonium, urea, nitrate, and nitrite.

Organic P is organically-bound phosphorus.  Like organic N, it is not water-soluble and must mineralize before it becomes available.  Most organic P is found as phytate.

Inorganic P is not associated with carbon; usually P dissolved in solution, such as PO43-, HPO42-, and H2PO4-.  Most P in manure and biosolids is in this form.

Dissolved P is found in the soil solution, as PO43-, HPO42-, and H2PO4-.

Particulate P is attached to soil particles.