Geology
What is weathering?
Process of breakdown of rocks, minerals, nutrients.
What process leads to removal of soil nutrients by movement of water?
Leaching
What is porosity?
The amount of space between particles.
What is the most valuable soil layer for plant growth?
Topsoil
What is the main source of soil minerals and nutrients?
Parent rock (Parent material)
Name two climate elements affecting the soil formation.
Temperature and Precipitation
What is permeability?
The ease with which gases and liquids can pass through the soil.
What is the main nutrient group needed for healthy plant growth?
N,P,K (nitrates, phosphates, potassium)
State the types of weathering.
Physical, Chemical and Biological.
How does excess rainfall impact soil fertility over time?
It removes soluble nutrients, depleting soil fertility.
How does low permeability affect plant nutrient access in clay soils?
It prevents roots from reaching minerals trapped between pores.
Why is fertile soil considered non-renewable?
Because it takes thousands of years to form but can be lost quickly through erosion or degradation.
Difference between Physical and Chemical Weathering
Physical: Breakdown of rocks into fragments without altering the chemical composition (exfoliation and thermal expansion)
Chemical: Change in the chemical composition of soil (Oxidation and Carbonation)
How can climate affect the rate of evaporation from the soil?
Hot and dry climates increase evaporation rates, drying out the soil. High humidity leads to decrease in rate of evaporation.
Why does sandy soil have high permeability even though its porosity is low?
Its larger pores allow water to flow freely without being trapped by adhesion.
Why is topsoil especially vulnerable to erosion?
Because it lies at the surface and is exposed to wind, water, and human activity.
Explain the link between parent rock composition and soil mineral content.
The type of minerals in the parent rock determines which nutrients and trace elements become available in the soil as the rock weathers.
Why are waterlogged soils less productive for agriculture?
Because excess water replaces air in soil pores, suffocating roots and promoting acidic, anaerobic conditions. (Increase in denitrification and Soil Acidity)
What implications does soil permeability have for irrigation and farming?
Soils with low permeability risk waterlogging and poor aeration, while highly permeable soils may require frequent watering. (Yes, Black soil example works here Chinmay)
How can legumes help maintain soil fertility?
They fix atmospheric nitrogen, enriching soil nitrogen content naturally.