Question

Organic manure adds organic matter called ____________ to the soil, which restores the soil texture for better retention of water and aeration of soil.
A. compost
B. animal manure
C. humus
D. Both A and C

Answer 1

Hint:Manure is actually the organic matter which is normally utilised as an organic fertilizer in agriculture. Organic manure mainly contributes towards the soil fertility by appending organic matter along with nutrients like nitrogen which are consumed by the microorganisms such as fungi, bacteria and other organisms present in the soil.

Complete answer:
In soil, organic matter is mainly composed of the animal and the plant material which is generally in the process of decomposing. When the material gets fully decomposed, it is known as humus. This humus is significant for the soil structure as it holds the individual mineral particles together in the form of clusters. So, humus basically refers to the fraction of the soil organic matter which is amorphous. Humus significantly affects the soil’s bulk density and contributes towards the nutrient and moisture retention. Actually, soil formation initiates with the weathering of the humus. We can say that humus is the dark organic matter which is formed in the soil with the decay of plant and animal matter. Humus is composed of many useful nutrients required for the healthy soil.
Thus, organic manure adds organic matter called humus to the soil, which restores the soil texture for better retention of water and aeration of soil.

Hence, the correct answer is Option C.

Note:
Humus is actually a colloidal substance which increases the cation exchange capacity of the soil, hence its capability to store the nutrients by the process of chelation. When these nutrient cations are available to the plants, they are held in soil and are prevented from being leached out by rain or irrigation.