Aspergillus niger is used to test the status of which element in the soil

Aspergillus niger is used to test the status of potassium elements in the soil. It is used as a test organism for determining Mg, Cu, Zn, Mo, etc in soil.
Aspergillus niger is a haploid filamentous fungus that is used for waste management and biotransformation in addition to its industrial uses, such as the production of citric acid and extracellular enzymes.