Question

The process of release of inorganic nutrients by the degradation of humus is called

• A. mineralisation
• B. leaching
• C. catabolism
• D. humification

Answer 1

The correct option is A mineralisation

The process of decomposition is the breakdown of complex organic materials present in dead remains of plants and animals into simple inorganic compounds. It is a major function of every ecosystem.

Detritus is the raw material for decomposition. The dead plant remains such as leaves, bark, flowers and dead remains of animals, including faecal matter, constitute detritus

Decomposition of detritus is a function of 5 different processes such as - fragmentation, leaching, catabolism, humification and mineralisation.

Fragmentation, leaching and catabolism work simultaneously on the detritus.

• Fragmentation refers to the breaking down of the detritus into smaller particles by the action of detritivores such as earthworms.
• Leaching: water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.
• Fungal and bacterial enzymes act on the detritus to degrade it into simpler inorganic substances. This process is called catabolism.

During decomposition, there is accumulation of a dark amorphous substance called humus. This process is called humification.

Humus is a nutrient-rich dark coloured, amorphous substance. Humus is a huge reservoir of nutrients. Being highly resistant to microbial action, humus decomposes very slowly. The humus is further degraded by some microbes and release of inorganic nutrients occurs by the process known as mineralisation.