Question

Fertile soil has lots of humus, why?

Answer 1

Hint : The role played by microorganisms is notable here. Also, the ingredients that make up humus are to be kept in mind while answering this question.

Complete answer :
Humus (a Latin term which literally means “earth” and “ground”), is made from decomposed organic matter like plants and animals. It is because of this reason that humus is very rich in microorganisms which help plants to absorb nutrients and be resistant to diseases. It is categorized as the top layer of dark organic matter that forms in the soil with the decaying of the dead plant and animal matter.
Humus contains many useful nutrients and minerals which make the soil healthy and suitable for plant growth. Among them, nitrogen is the most important; it is especially essential for plant growth as it is responsible for vegetative growth and enhances the protein build-up in the plant. To be specific, the composition of humus is- around 60% carbon, 6% nitrogen, and smaller amounts of phosphorus and sulfur.
Soils lacking humus tend to become extremely compacted, coarse, and airless which form very hard crusts that resist the infiltration of air, rain, or irrigation water and as a result prevent the germination of seedlings.

Additional information:
 Some important functions of humus-
It makes the soil more porous which improves soil aeration, infiltration, and drainage,
It improves the structure of the soil and enhances soil to retain important nutrients,
Soils rich in humus help plants to grow more easily.
Its biochemical structure enables it to moderate excessive acid or alkaline soil conditions.
It holds the equivalent of 80 to 90% of its weight in moisture which increases the soil’s capacity to withstand drought conditions.
It supports the growth of an essential organism called mycorrhizal fungi which forms a symbiotic relationship with many plants and acts as an important factor in the soil food web.

Note : Humus isn’t a very expensive necessity; it can be prepared at home by mixing up primarily coffee grounds and tea leaves; other kitchen waste such as moulded bread and vegetable cores can be utilized too for the purpose.