Question

Which of the following present in the soil is most helpful to the growth of plants:
A. Gravel
B. Humus
C. Sand
D. Silt

Answer 1

Hint: Soil is the upper layer of the earth. Soil is composed of various types of mineral particles. The soil formation is the result from the degradation of the basement rock, due to certain physical, chemical and biological processes.

Complete answer:
This is a medium that typically consists of organic dust or junk, clay and mineral particles but there’s also other components to soil, those are essential for life.
-Gravel: is also known as pebble. It is good for drainage but not good for fertility.
-Humus: It is a unique part of the top soil. Humus is a large number of natural organic compounds found in the soil. Which is formed from the chemical and biological decomposition of plant and animal residues and from the synthetic activity of microorganism.
There are some of beneficial influences which can be helpful in growth of the plants:
Humus makes the soil more porous and improves the soil aeration.
It’s able to absorb certain toxic elements
It helps to increase the nutrients and water holding capacity of soil.
It acts like binding the particles together and preventing them washing or blowing away.
Humus can determine the structure and fertility of the soil.
Humus is also rich in microorganisms. Some of them are help in decomposition and the other are to assist the plants in absorbing the nutrients
-Sand: It is warm airy soil. The sand particles are very fine, which cannot hold the water and nutrients. So, it is important to be careful while watering the plant.
-Silt: it is made up of rock and mineral particles, which is smaller than the sand and larger than the clay.
Thus, the correct answer is B, Humus.

Note: Humus soil provides a large amount of nutrients including metals and minerals to the plants. And it contains a range of microorganisms which break down the plant waste and help the roots to absorb the nutrients from the soil. These two main functions of humus soil help the plant to grow more easily.