Question

Humus is important for plant growth because
(a) It is partially decomposed
(b) is derived from leaves
(c) It is rich in nutrients and increases the water holding capacity of the soil.
(d) It is made up of dead organic matter
(e) All of the above

Answer 1

Hint: Humus is the uppermost layer consisting of raw matter from plants and animals and other resources that are important for the terrestrial ecosystem. It provides nourishment and is a reservoir for resources. It is colloidal.

Complete answer:
Humus is partially decomposed and is made up of remains of plants and animals, which by the action of microorganisms are converted into essential nutrients and organic matter which helps the terrestrial life dependent on soil grow and flourish.
Humus is important for plant growth because
- It makes soil porous, improving the aeration.
- it is responsible to maintain the fertility of the soil.
- It increases the water- holding capacity of the soil.
- It supports the growth of all beneficial microorganisms like mycorrhizal fungi.
So, the correct answer is, ‘All of the above.’

Additional Information:
Soil is one of the most important factors for the terrestrial ecosystem. It is the reservoir for all the minerals and nutrients necessary for living organisms. Soil is formed by the continuous weathering of rocks.
Humus is the topmost layer, brown to black, and rich in organic matter.it consists of about 60 percent carbon and 6percent nitrogen also sulfur and phosphorus in smaller amounts.

Note: When the plants drop their leaves, branches, and other material to the ground, it is collectively called leaf litter. When animals die, their remains are added to the litter as well and overtime all this litter decomposes by the action of microorganisms and it decays into the most basic chemical elements which are important for the nutrients for the soil and the organisms which depend on soil for life, like plants. This process of formation of humus from dead organic matter is called Humification.