PO 31. Define the following nutrient terms.
- Total Kjeldahl Nitrogen (TKN)
- Organic N
- Inorganic N
- Organic P
- Inorganic P
- Dissolved P
- 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. |