Question

What is humus? Distinguish between Mor and Mull humus.

Answer 1

Humus: Soil with organic matter that is partially or entirely decomposed is called humus.
Importance of humus: It is porous and contains appropriate amount of water. Humus contains proteins and lignin in different proportion so it is called lignoprotein. Clay humus and hydroxides of aluminium and iron combine in various proportions to form colloidal complex. The increase in the concentration of colloidal complex in the soil results in the improvement of soil fertility.
Types of humus: On the basis of parent matter and climatic conditions, Muller (1800) divided humus into two types.
(1) Mor humus: This is non-porous and friable humus. It lacks earthworms and possesses less number of microorganisms. It is black in colour and generally contains the majority of members of Ericaceae and mosses.
(2) Mull humus: It is porous. It is brown in colour and found in the forest soil. It has very less number of micro-organisms. It is suitable for the growth of bacteria and fungi.