Read the given passage and answer the questions that follow:
The earthworm is often referred to as the farmer's 'friend' due to its beneficial role in the breakdown of complex organic matter and soil aeration. Similarly, decomposers play a crucial role in converting complex organic matter into inorganic substances like carbon dioxide, water, and nutrients through the process of decomposition. Detritus, consisting of dead plant remains (leaves, bark, flowers) and animal waste, serves as the raw material for decomposition. Decomposition involves several important steps: fragmentation, leaching, catabolism, humification, and mineralization.
Which of the following makes decomposition faster?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Detritus rich in nitrogen and water-soluble substances like sugars
The rate of decomposition is controlled by the chemical composition of the detritus and by climatic factors. Easily broken-down material and a warm, moist, airy soil make it fast; tough material, cold and lack of oxygen make it slow.
Option (1) Detritus rich in lignin and chitin — Incorrect. Detritus rich in lignin and chitin decomposes slower, because these substances are hard for microbes to break down.
Option (2) Detritus rich in nitrogen and water-soluble substances like sugars — Correct. In a given climate, detritus rich in nitrogen and water-soluble substances like sugars decomposes quicker.
Option (3) Low temperature and anaerobiosis — Incorrect. Low temperature and anaerobiosis inhibit decomposition, so organic matter builds up.
Option (4) Warm temperature and anaerobiosis — Incorrect. Warmth helps decomposition, but anaerobiosis inhibits it, since decomposition is largely an oxygen-requiring process.
NCERT Extract:
Decomposition – “Decomposition is largely an oxygen-requiring process. The rate of decomposition is controlled by chemical composition of detritus and climatic factors. In a particular climatic condition, decomposition rate is slower if detritus is rich in lignin and chitin, and quicker, if detritus is rich in nitrogen and water-soluble substances like sugars. … Warm and moist environment favour decomposition whereas low temperature and anaerobiosis inhibit decomposition resulting in build up of organic materials.”