Reserve Potassium (TBK)

Tap into the ability of some soils to release potassium over time

This test measures:

Potassium captured within the clay structures of the soil that is not extracted by the conventional quick soil test. It is the fraction of potassium that is slower to become plant available

Best time to run this test:

As an extra test during routine soil testing on sedimentary and recent soils.


Measures the amount of reserve potassium available in some soils. Recommended every three to five years on sedimentary soils only.


Provide an indication of potentially available potassium over time that can supplement the easily available potassium pool.

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