Question

The rate of decomposition of detritus is affected by abiotic factors like availability of oxygen, pH of the soil substratum, temperature, etc. Discuss.

Answer 1

Hint: Detritus is the dead particulate organic material. It typically includes the bodies or fragments of bodies of dead organisms and faecal materials.

Complete answer: Decomposition is the breaking down or disintegration of complex organic matter into simpler compounds. The rate of decomposition is affected by both biotic and abiotic factors.
Abiotic factors include the following:
a) Availability of oxygen: It is important for the process of decomposition as it is an energy-requiring process. Further, the aerobic bacteria taking part in the process require oxygen for survival and efficiency. Loose soil provides more chance for atmospheric oxygen to permeate the soil.
b) pH: Acidic pH (lower pH) is detrimental to the bacterial population. This results in a decrease in the rate of decomposition. Hence, alkaline nature (higher pH) has a positive effect on the rate of decomposition.
c) Soil substratum: The rate of decomposition is higher in the superficial soil strata and decreases gradually downwards.
d) Temperature: Relatively higher temperature accompanied by a moist environment has a positive effect on the rate of decomposition.
e) Nitrogen: Its presence along with sugars increases the rate of decomposition to a moderate extent
Decomposition occurs by the following steps; fragmentation, leaching, catabolism, humification, and mineralization. Fragmentation is the breakdown of detritus into smaller pieces by the detritivores (mostly invertebrates). Leaching is the process of dissolving water-soluble nutrients and seeping into the soil to get precipitated. Whereas mineralization is the process of degradation of hummus to release inorganic nutrients.

Note: Catabolism is the breakdown of complex material into smaller particles and inorganic nutrients. While humification is the process of formation of a dark-coloured layer of amorphous substance on the soil called humus, which is highly fertile.