Question

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

• A. Fragments- carried out by organism such as earthworm.
• B. Humification- leads to the accumulation of a dark coloured substance humus which undergoes microbial action at a very fast rate.
• C. Leaching- water soluble inorganic nutrients rise to the top layers of soil.
• D. Catabolism- last step in the decomposition under fully anaerobic condition.

Answer 1

Answer: (A)

Decomposition of plant matter occurs in many stages. It begins with leaching by water; the most easily lost and soluble carbon compounds are liberated in this process. Another early process is physical breakup or fragmentation of the plant material into smaller bits which have greater surface area for microbial colonization and attack. In smaller dead plants, this process is largely carried out by the soil invertebrate fauna, whereas in the larger plants, primarily parasitic life-forms such as insects and fungi play a major breakdown role and are not assisted by numerous detritivore species. Following this, the plant detritus (consisting of cellulose, hemicellulose, microbial products, and lignin) undergoes chemical alteration by microbes.

Humification is a process that occurs in soils and peats which sees organic material decompose and break down.

Catabolism is the set of metabolic pathways both aerobic and anaerobic that breaks down molecules into smaller units to release energy.