What is nutrient immobilization?

Hint: To derive the correct answer, you must first know that nutrient mineralization and nutrient immobilization are two opposite processes. In the process of nutrient mineralization, nutrients are converted from their organic form to their inorganic form so that they can be supplied with these nutrients. As these two processes are opposite, can you guess what nutrient immobilization really is?

Complete answer:
As already mentioned above, nutrient mineralization is a process by which the nutrients are being available for plant uptake by converting from its organic to its inorganic form. However as also mentioned, the process of nutrient immobilization is opposite to that of mineralization whereby the microorganisms take up minerals from the soil so that they remain unavailable to plants for use. Immobilization of minerals is generally done by bacteria present in soil. For example, a bacteria in soil takes up nitrogen in its inorganic state. When inside the cell, this nitrogen is being used up in the formation of amino acids and proteins. As a result, they are incapable of being used up and taken up by the plants. The process of nutrient mineralization and nutrient immobilization occur continuously in the soil to maintain equilibrium.

Note:
We can always know whether the nitrogen present in the soil is immobilized or not. This depends on the C to N ratio. If the C to N ratio is about 30:1, then the microbes present in soil can take up nitrogen in the mineralized form. Nitrogen is then known as immobilized. If the C to N ratio falls below 25:1, then nitrogen is said to be mineralized and is ready for use by the plants and can readily be taken up.