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Each point: 1 Mark
Any 3
(a) For enabling easy root growth
(b) For easier percolation of water
(c) For aerating the soil/enabling air to get into deeper layers of soil
(d) For removing the weeds​​​​​​​

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Definition: 1 Mark
Explanation: 2 Marks
The removal of land surface by water, wind or ice is known as erosion.
Plant roots firmly bind the soil. In the absence of plants, the soil becomes loose. So it can be moved by wind and flowing water. Erosion of soil is more severe in areas of little or no surface vegetation, such as a desert. So, cutting of trees and deforestation should be prevented and effort should be made to increase the number of trees.

:
Following are the soil types in the decreasing orderof the size of theparticulate matter.

• Clay


• Silt


• Sand


• Gravel

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Explanation: 1 Mark
Naming: 2 Mark
Each layer of soil differs in feel (texture), colour, depth and chemical composition. These layers are called horizons.
The three horizons of soil are:
1) A-Horizon
2) B-Horizon
3) C-Horizon

:
Definition: 2 Marks
Formula: 1 Mark
Solution: 2 Marks
Water absorption rate of the soil is defined as the capacity of the soil to absorb water from the surrounding areas in a specific amount of time. It is also called the water retention capacity of soil.
Now the details of the soil sample is:
Amount of water = 360 mL
Time taken for this amount to percolate down the sample= 60 minutes
hence
Rate of percolation = $\frac{\text{Amount of water (mL)}}{\text{Percolation time (min)}}$ = $\frac{\text{360 mL}}{\text{60 m}}$ =6 mL/min
Ans: 6 mL/min

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Each part: 1 Mark
i. A vertical section through different layers of the soil is called soil profile.
ii. Weatheringis theprocessby whichsoil isformed.
iii. Water drains quickestthrough sandy soil.

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Definition: 1 Mark
Diagram: 1 Mark
Soil permeabilityis the property of thesoilto transmit water and air.
.

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Each point: 0.5 marks
Soil consists of:
1. Inorganic mineral matter ( about 40 to 45 percent of the soil volume)
2. Organic matter (about 5 percent of the soil volume)
3. Water (about 25 percent of the soil volume)
4. Air (about 25 percent of the soil volume)

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Reasons: 1 Mark each
Clayey soil is useful for growing crops because of the following reasons:
(i) It has very good water retaining capacity.
(ii) This soil is rich in humus and is very fertile.
(iii) It contains useful organic minerals.

:
Names of pollutants: 1 Mark each
The major soil pollutants are
1. Pesticides and insecticides: Excessive use results in rampant leaching of these chemicals into the soil
2. Plastic bags: Don't get decomposed which lowers the soil fertility.
3.Industrial waste: When recklessly dumped, kills useful microorganisms in the soil.