During the process of decomposition, a dark-coloured amorphous substance accumulates which is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. Identify the process responsible for the accumulation of this substance, and the process by which it is subsequently degraded by some microbes to release inorganic nutrients, respectively.

Step-by-step solution

The dark-coloured amorphous substance described in the question is humus. It is highly resistant to microbial action and serves as a reservoir of nutrients. The process that leads to the accumulation of humus in the soil is called humification. The humus is further degraded by some microbes to release inorganic nutrients through a process known as mineralisation. Therefore, the correct sequence of processes is Humification followed by Mineralisation. Reversing the order or selecting other steps of decomposition lik