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CBSE NCERT Solutions for Class 7 Science Chapter 9:
Explain how soil pollution and soil erosion could be prevented.
Steps for preventing soil pollution and soil erosion:
(i) Plantation should be encouraged because plant roots firmly bind the soil and help in preventing erosion.
(ii) Methods like crop rotation and mixed farming should be followed.
(iii) Use of organic fertilizers and manure instead of synthetic.
(iv) Pesticides and insecticides should be used in limited quantity and find natural way to prevent it.
(v) Plastic bags should b banned and it doesn't decompose and gives rise to soil
(vi) Industrial waste shouldn't be dumped directly as it kill necessary micro organisms of soil.
Explain how soil is formed.
The soil is formed by the process of weathering in which the rocks break down by the action of wind, water and climate. It is a very slow process and big rocks get converted into soil.
How is clayey soil useful for crops?
Clayey soil is very useful for crops because:
(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. These properties of loamy soil is very suitable for growing crops.
In addition to the rock particles, the soil contains
(i) air and water
(ii) water and plants
(iii) minerals, organic matter, air and water
(iv) water, air and plants
Minerals, organic matter, air and water