Which one of the following processes during decomposition is correctly described?

Correct answer: C. Fragmentation - Carried out by organisms such as the earthworm

  • A. Catabolism - Last step in decomposition under fully anaerobic conditions
  • B. Leaching - Water soluble inorganic nutrients rise to the top layers of soil
  • C. Fragmentation - Carried out by organisms such as the earthworm
  • D. Humification - Leads to the accumulation of a dark coloured substance humus which undergoes microbial action at a very fast rate.

Explanation

Decomposition is the process in which decomposers break down complex organic matter into inorganic substances like carbon dioxide, water and nutrients. The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and mineralisation. Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called fragmentation. By the process of leaching, water­ soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts. Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called catabolism. Humification and mineralisation occur during decomposition in the soil. Humification leads to the accumulation of a dark coloured amorphous substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. The humus is further degraded by some microbes and the release of inorganic nutrients occur by the process known as mineralisation.

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