Question

Humus is found in
A. Top portion of soil
B. Middle portion of soil
C. Deep portion of soil
D. None of the above

Answer 1

Hint: Humus is a type of non-living and divided organic matter that is present in the soil. It is derived from the microbial decomposition of plant and animal substances. The colour of humus can range from brown to black.

Complete answer:
Humus can be simply referred to as a fertile and important component of the soil. Humus is the organic nutrient rich material as it is produced due to the microbial decomposition of plant and animal substances. Humus can be seen in the top or 'A' horizon of soil structure. The 'A' horizon is dark-coloured spongy topsoil. This horizon of the soil is enriched with important mineral and organic products and in this zone, the maximum biological activity and rooting of plants takes place. This organic matter is mainly made up of non-living and decaying animal substances, dried leaves, twigs, grasses, vegetables, microbes, and some other nutrients. Humus is naturally produced in the soil and the process through which it can be easily produced is known as composting. Humus is also referred to as mineral soil. So, it is widely applied by farmers and gardeners for the improvement of their plant’s yield. Humus has a number of ecological and economical significance. The major significance of Humus is to help with the improvement of crop production. It is also used to improve the fertility of the earth. By rapid absorption, it increases the water content in the soil. Humus also helps to increase the workability of the soil. Humus can be categorized into three types of formation which are mor-humus formation, mull-humus formation, and modern-humus formation. This classification is done based on the degree of its incorporation into the mineral soil, the types of organisms involved in its decomposition, and the vegetation from which it is derived.
Thus, the right option is A.

Note: Humus can be defined as a dark, organic material is generated in the soil when plant and animal matter decompose. It is a thick brown or black substance that exists after most of the organic litter has decomposed. In humus, there are various useful nutrients for healthy soil. One of the most important compounds present in humus is nitrogen. It forms the top or 'A' horizon of soil structure.