The breakdown of rocks and minerals, known as weathering, is a foundational process that prepares the raw materials for soil. Physical weathering cracks and fragments rocks through forces like freezing water and wind abrasion, while chemical weathering alters their composition via reactions with water and air. The prevailing climate and the inherent properties of the rocks dictate how rapidly and in what manner weathering occurs.
Its formation is a gradual process influenced by the original rock, the climate of the region, the activity of living organisms, the passage of time, and the lay of the land. Over time, soil often develops distinct layers. However, the valuable topsoil is susceptible to erosion by wind and water, a problem often exacerbated by human activities. Therefore, implementing conservation strategies is vital to protect and sustain this essential natural resource.
Discuss
From encycopaedias and the Internet, find out the different types of soil found in India. Discuss the importance of these soils for crops cultivated in our country. You should form groups in class for this activity.
Ans:
The diverse geological and climatic conditions across India have fostered the development of eight major soil classifications, each exhibiting distinct properties that favor particular agricultural practices. The rich alluvial deposits along river systems form highly productive lands, crucial for staple crops like rice and wheat. The black soils of the Deccan plateau, known for their moisture retention, are particularly well-suited for cotton cultivation. In the southern and eastern regions, red and yellow soils, when supplemented with irrigation, support the growth of millets and pulses. The intensely weathered laterite soils of high rainfall zones provide ideal conditions for plantation crops such as tea and coffee. Despite their limitations, arid soils in the western regions can become productive for certain crops with irrigation techniques, while the varied mountain soils are essential for cultivating fruits and spices. The less fertile saline and alkaline soils present challenges but can support limited agriculture with appropriate management, and the waterlogged peaty soils are conducive to rice cultivation in specific areas. This inherent soil heterogeneity underpins the wide array of agricultural activities across the Indian subcontinent.
THINK AND ANSWER
Soil formation is an important benefit of weathering. How is it important for mankind ?
Ans:
The creation of soil through weathering is fundamentally crucial for humanity. Primarily, it underpins all terrestrial food systems, providing the necessary nutrients, water retention, and physical support for plant growth, which directly sustains human populations through agriculture. Beyond food, soil plays an indispensable role in environmental regulation, acting as a natural filter for water, contributing to groundwater recharge, and participating in vital nutrient cycles that maintain ecosystem health and a stable environment essential for human well-being.
VALUES AND LIFE SKILLS
People have used various farming methods to increase food production. However, in the process, they have stripped soil of nutrients, leading to its degradation.
Can you suggest some ways by which we can reduce soil degradation ?
Ans:
To reduce soil degradation from intensive farming, we can use crop rotation to balance nutrient use, plant cover crops to protect and enrich the soil, and practice conservation tillage to minimize disturbance. Organic farming and integrated pest management avoid harmful chemicals. Efficient irrigation prevents waterlogging and salinization. Integrating agroforestry adds stability. Directly adding organic matter and using soil testing for targeted fertilization improve soil health. On slopes, contour farming and terracing curb erosion, while windbreaks help on flat land. Supportive government policies and farmer education are also crucial for widespread adoption of these sustainable practices.
EXERCISES
A. Match the column
Answer:
B. Distinguish between each of the following pairsQuestion 1.
Degradation and aggradation
Ans :
| Feature | Degradation | Aggradation |
| Process | Wearing down and lowering of the Earth’s surface. | Building up and raising of the Earth’s surface. |
| Action | Erosion (removal of material). | Deposition (accumulation of material). |
| Outcome | Decrease in elevation; formation of valleys, canyons. | Increase in elevation; formation of floodplains, deltas. |
| Driving Force | Kinetic energy of erosional agents (water, wind, ice). | Decrease in energy of transporting agents, leading to sediment settling. |
| Nature | Destructive process. | Constructive process. |
Question 2.
Weathering and erosion
Ans:
| Feature | Weathering | Erosion |
| Definition | The breakdown of rocks, soil, and minerals into smaller pieces. | The movement of weathered material from one place to another. |
| Action | Disintegration and decomposition of Earth’s materials in place. | Transportation of broken-down material by natural agents (water, wind, ice, gravity). |
| Movement | No significant movement of material occurs. | Material is actively carried away. |
| Driving Force | Physical forces (temperature changes, frost wedging, abrasion, biological activity) and chemical reactions (oxidation, hydrolysis, carbonation). | Gravity and the kinetic energy of transporting agents (water flow, wind speed, glacial movement). |
| Outcome | Creation of smaller fragments, altered mineral composition, weakened rock structures. | Shaping of landscapes through the removal and deposition of sediment. |
Question 3.
Granular disintegration and exfoliation
Ans:
| Feature | Granular Disintegration | Exfoliation |
| Process | Breakdown of rocks into individual grains or small particles. | Peeling off of rock layers in sheets or shells. |
| Scale of Breakdown | Grain by grain separation. | Layer by layer separation. |
| Appearance | Results in a rough, pitted, or sandy surface. | Results in curved or sheet-like features, often dome-shaped. |
| Primary Cause | Differential expansion and contraction of individual minerals within the rock due to temperature changes (different minerals expand/contract at different rates). Can also be caused by salt crystal growth in pore spaces. | Pressure release (unloading) as overlying rock erodes, causing expansion and fracturing parallel to the surface. Also, differential heating and cooling of the outer rock layers compared to the inner layers. |
| Rock Type Susceptibility | Commonly occurs in coarse-grained crystalline rocks (e.g., granite) where minerals have varying properties. | More common in massive, jointed rocks like granite and basalt. |
| Analogy | Like sand falling apart from a loosely cemented stone. | Like peeling layers off an onion or the skin flaking off after sunburn. |
Question 4.
Hydration and solution
Ans:
| Feature | Hydration | Solution |
| Definition | A chemical reaction where water molecules chemically combine with a substance. Water becomes part of the new compound’s crystal structure (forming a hydrate). | A process where a substance (solute) dissolves uniformly into another substance (solvent) to form a homogeneous mixture. No new chemical compound is necessarily formed. |
| Water’s Role | Water is a reactant, forming a new, often crystalline, compound containing water molecules in a fixed ratio. | Water (if the solvent) acts as a medium to disperse the solute molecules or ions. Water molecules surround the solute particles (solvation, specifically hydration when water is the solvent). |
| Chemical Bonding | Water molecules are chemically bonded within the crystal lattice of the hydrate. | The solute particles are dispersed among the solvent molecules; there isn’t necessarily a strong chemical bond between them (though intermolecular forces exist). |
| Reversibility | Often reversible by heating, which drives off the water molecules, returning to the anhydrous form. | The solute can often be recovered by physical processes like evaporation or crystallization. |
| Examples | Formation of copper(II) sulfate pentahydrate (CuSO₄·5H₂O) from anhydrous copper(II) sulfate (CuSO₄). | Dissolving salt (NaCl) in water to form a saline solution. Dissolving sugar in water. |
Question 5.
Soil erosion and soil conservation
Ans:
| Feature | Soil Erosion | Soil Conservation |
| Definition | The wearing away and removal of topsoil from the land surface by natural forces (water, wind, ice, gravity) or human activities. | The prevention of soil loss or degradation and the protection and improvement of soil quality. |
| Process | Detachment, transport, and deposition of soil particles. | Implementing practices to protect the soil from erosion and maintain its health. |
| Cause | Natural factors (rainfall, wind, slope) and human activities (deforestation, overgrazing, poor farming practices, construction). | Implementing sustainable land management practices. |
| Effect | Loss of fertile topsoil, reduced agricultural productivity, water pollution, sedimentation of water bodies, land degradation, increased flooding risk. | Maintenance of soil fertility, prevention of land degradation, improved water quality, reduced sedimentation, sustainable agriculture. |
| Examples | Gully erosion, sheet erosion, wind erosion, landslides due to deforestation. | Terracing, contour plowing, afforestation, cover cropping, crop rotation, no-till farming. |
C. Give geographical reasons
Question 1.
Temperature changes result in physical weathering.
Ans:
Temperature fluctuations are a key factor in the physical breakdown of rocks. When rocks are heated, they expand, and when they cool, they shrink. Moreover, the different minerals that constitute a rock expand and contract at varying rates when exposed to the same temperature change. This differential movement creates additional stress along the boundaries between these minerals. Over prolonged periods, these stresses can exceed the rock’s resistance, leading to the formation of cracks and ultimately causing the rock to break apart into smaller pieces. This mechanism, often referred to as thermal expansion and contraction or thermal stress weathering, is particularly influential in environments that experience significant and frequent temperature variations, such as arid desert regions with extreme daily temperature swings or high-altitude areas with considerable day-night temperature differences.
Question 2.
Gases in the atmosphere affect weathering.
Ans:
The gases composing Earth’s atmosphere exert a substantial influence on the weathering of rocks, primarily through chemical interactions. Carbon dioxide dissolves within rainwater, yielding carbonic acid, a mildly corrosive substance that effectively breaks down carbonate-rich rocks like limestone and chalk. This chemical process is central to the formation of distinctive karst topographies and subterranean cave systems. Oxygen present in the atmosphere facilitates oxidation, a reaction where it combines with various minerals, notably those containing iron, leading to their alteration and weakening, thereby increasing the rock’s vulnerability to further disintegration.
Beyond natural atmospheric components, anthropogenic pollutants, including sulfur dioxide and nitrogen oxides, react with atmospheric moisture to produce acid rain (comprising sulfuric and nitric acids). This acidic precipitation significantly accelerates the chemical breakdown of a wide spectrum of rock types and mineral compositions. The consequences extend beyond natural landscape modification, causing considerable damage to human-made structures, historical monuments, and ecological balance. Consequently, the specific gaseous makeup of the atmosphere is a critical factor governing the rate and nature of rock decomposition at the Earth’s surface.
Question 3.
Human activities affect weathering.
Ans:
A primary way humans impact weathering is through atmospheric pollution. The combustion of fossil fuels releases compounds such as sulfur dioxide (SO2) and nitrogen oxides (NOx) into the atmosphere. These pollutants undergo chemical reactions in the atmosphere, leading to the formation of acid rain, which contains sulfuric acid and nitric acid. Acid rain significantly enhances chemical weathering, particularly the dissolution of carbonate-rich rocks like limestone and marble, resulting in the accelerated degradation of buildings, sculptures, and natural rock formations.
Moreover, land-use changes like deforestation and intensive agriculture can increase the exposure of soil and rock to weathering agents. The removal of vegetation eliminates the protective layer provided by plant roots and leaf litter, making the underlying material more susceptible to erosion by wind and water, as well as greater temperature fluctuations leading to increased thermal expansion and contraction. Direct physical disturbance through mining and construction involves the large-scale fragmentation of rocks, exposing new surfaces to weathering and potentially releasing reactive chemicals. Even recreational activities like hiking and off-roading can contribute to physical weathering by fracturing and destabilizing rock and soil.
Question 4.
Soil is a very important resource.
Ans:
Soil stands as a fundamentally crucial and largely irreplaceable natural resource, underpinning the very fabric of terrestrial life. It serves as the essential medium for the cultivation of the vast majority of our food crops, providing the necessary nutrients, water retention capabilities, and physical support for plant root systems that sustain human and animal populations alike. Beyond agriculture, soil plays a vital role in regulating water cycles by absorbing and storing rainwater, thereby mitigating the risks of floods and droughts, and naturally filtering water to replenish underground aquifers.
Furthermore, soil is a dynamic and intricate ecosystem, teeming with a diverse array of microorganisms that are instrumental in the decomposition of organic matter and the continuous cycling of critical nutrients, making them accessible to plant life. It also provides habitat for a significant portion of Earth’s biodiversity, contributing to overall ecosystem health. Healthy soils are also important carbon sinks, helping to sequester atmospheric carbon and mitigate climate change. While often considered in a different context, soil also provides the foundational stability required for much of our infrastructure and construction. Given the extremely slow rate of topsoil formation compared to the speed at which it can be degraded or lost, the preservation and sustainable management of this indispensable resource are paramount for both present and future generations.
Question 5.
There is a need for soil conservation.
Ans:
The necessity for soil conservation is an undeniable and critical imperative, stemming directly from the fundamental importance of soil as a natural resource. Given its pivotal role in sustaining life and supporting numerous ecological and human systems, the degradation and loss of soil pose significant threats to our well-being and the health of the planet.
Ensuring future food security for a growing global population hinges on the preservation of fertile topsoil, as it forms the bedrock of agricultural productivity. The erosion and degradation of this vital layer directly undermine our capacity to produce sufficient food supplies. Furthermore, soil plays a crucial role in safeguarding water resources. Soil erosion leads to the contamination of rivers, lakes, and reservoirs through sediment runoff, and soil conservation practices are essential for maintaining clean water supplies and preventing the sedimentation of water bodies.
Healthy soils are also integral to the functioning of terrestrial ecosystems, supporting a vast diversity of life and contributing to overall ecological stability. Soil degradation disrupts these intricate ecosystems and can lead to habitat loss and a decline in biodiversity. Moreover, the capacity of healthy soils to sequester and store carbon is a significant factor in mitigating the impacts of climate change. Conversely, the degradation of soil can release stored carbon back into the atmosphere, exacerbating the problem.
Preventing land degradation, including erosion and desertification, is another crucial aspect of soil conservation, as it ensures the long-term productivity and usability of land resources, safeguarding livelihoods and preventing environmental decline. Economically, sectors such as agriculture and forestry are directly reliant on healthy soil, and its degradation carries substantial economic costs. Finally, healthy soil enhances the land’s capacity to absorb water, thereby reducing the risks and severity of natural disasters like floods and landslides.
In essence, soil conservation transcends being merely an environmental concern; it represents a fundamental economic, social, and humanitarian necessity for the enduring well-being of our planet and all its inhabitants. Neglecting the conservation of this critical resource will inevitably lead to severe and widespread negative consequences.
D. Answer the following questions in brief
Question 1.
Name any four agents of erosion.
Ans:
Here are four key agents of erosion:
- Water: This is the most significant agent globally. Running water in rivers and streams, rainfall, waves, and runoff all work to detach and transport soil and rock particles.
- Wind: Especially effective in arid and semi-arid regions with sparse vegetation, wind can pick up and carry loose sediment over considerable distances.
- Ice (Glaciers): The immense weight and slow movement of glaciers can carve out valleys, pluck rocks from the ground, and transport vast amounts of debris.
- Gravity: Gravity causes the downslope movement of weathered material, leading to mass wasting events like landslides, rockfalls, and soil creep.
Question 2.
List any three factors that affect weathering.
Ans:
Climate: Temperature and rainfall dictate the type and speed of weathering. Warm and wet areas favor chemical weathering, while cold and wet areas enhance physical weathering like freeze-thaw.
Rock Type: The minerals a rock contains and its structure (e.g., cracks) determine its resistance to breakdown. Softer, fractured rocks weather faster.
Surface Exposure: The more of a rock that’s exposed to the elements (due to fragmentation or cracks), the quicker it will weather.
Question 3.
In which regions of the world is ‘frost action’ the common form of weathering?
Ans:
Mid-latitude regions with pronounced seasonal temperature changes: Areas within the temperate zones of North America, Europe, and Asia that experience winters with numerous instances of temperatures fluctuating above and below freezing are highly susceptible to frost action. Mountainous terrains within these latitudes often experience even more intense freeze-thaw cycles due to variations in altitude.
High-altitude environments globally: Mountain ranges around the world, even those located in lower latitudes, frequently undergo daily freeze-thaw cycles at higher elevations. The thinner atmosphere at these altitudes leads to rapid cooling at night, allowing water trapped in rock fissures and pores to freeze and expand.
Periglacial zones: These are environments situated at the edges of glaciers and ice sheets, characterized by cold climates and a surface layer that seasonally thaws above permanently frozen ground (permafrost). Frost action is a dominant geomorphic process in these regions, shaping unique landforms. Examples include parts of Alaska, Canada, Siberia, and the margins of Greenland and Antarctica.
Subpolar and polar regions: While predominantly experiencing sub-zero temperatures, occasional thawing periods during warmer parts of the year (or even due to solar radiation on dark-colored rocks)
Question 4.
Which is the most important effect of weathering?
Ans:
The Bedrock of Terrestrial Life: Soil, a product of the disintegration of rocks combined with organic matter, serves as the indispensable substrate for the growth of the vast majority of plant life on Earth. Plants, in turn, form the base of nearly all terrestrial food chains, providing both sustenance and the oxygen necessary for animal and human survival. Without the formation of soil through weathering, conventional agriculture would be impossible, and terrestrial ecosystems would be dramatically altered, with significantly reduced biodiversity and productivity.
Release of Essential Nutrients: The breakdown of rocks through weathering liberates crucial minerals and nutrients into forms that can be absorbed by plants via the soil. This continuous cycling of nutrients is vital for sustaining healthy plant growth and maintaining the overall functionality of terrestrial ecosystems.
Question 5.
What are the components of topsoil?
Ans: Its composition is a dynamic interplay of several key constituents:
- Inorganic Mineral Particles: Forming the largest proportion of topsoil (ideally around 45%), this component consists of fragmented rock and mineral material derived from the weathering of underlying parent rock. These particles are classified by size as sand, silt, and clay, and their relative proportions dictate the soil’s texture, influencing drainage, aeration, and water-holding capacity.
- Decomposed Organic Matter (Humus): Though typically comprising a smaller percentage (around 5% in optimal conditions), organic matter, in its stable, decomposed form known as humus, is vital for soil health and fertility. Humus is the result of the breakdown of plant and animal residues and significantly improves soil structure, enhances water retention, provides essential nutrients to plants, and supports a thriving soil ecosystem.
- Soil Water: Occupying the pore spaces between solid soil particles, water is indispensable for plant growth as it acts as a solvent for nutrients and facilitates their transport to plant roots. The amount of water present in topsoil fluctuates based on factors such as precipitation, drainage patterns, and evaporation rates.
- Soil Air: The composition of soil air can differ slightly from atmospheric air, often containing a higher concentration of carbon dioxide due to biological activity.
- Living Organisms: Topsoil is a vibrant ecosystem teeming with a multitude of life forms:
- Microscopic Organisms: Bacteria, fungi, algae, and protozoa play essential roles in the decomposition of organic materials, the cycling of nutrients, and the development of soil structure.
- Macroscopic Organisms: Earthworms, insects, nematodes, and small burrowing animals contribute to soil aeration, the mixing of organic matter throughout the soil profile, and the breakdown of larger organic debris.
Question 6.
Name the various methods of conserving soil.
Ans:
Soil conservation employs agronomic methods like contour farming, terracing, and cover cropping to manage water flow and protect the soil surface. Structural methods involve building barriers like windbreaks, check dams, and retention ponds to physically prevent erosion. Biological methods focus on using vegetation, such as afforestation, maintaining plant cover, and controlled grazing, along with soil amendments, to improve soil health and stability. These approaches, often combined, aim to prevent soil loss and maintain its fertility for long-term sustainability.
Question 7.
Distinguish between contour tilling and contour bunding.
Ans:
| Feature | Contour Tilling (Contour Ploughing/Farming) | Contour Bunding |
| Main Action | Plowing and planting crops along contour lines (across the slope). | Constructing small earthen or stone barriers (bunds) along contour lines. |
| Primary Goal | Reduce soil erosion by slowing down water runoff and increasing infiltration along the furrows created by plowing. Also helps conserve moisture. | Intercept and hold rainwater runoff to increase infiltration, reduce soil erosion, and conserve moisture. Can also help trap sediment. |
| Structure | Creates furrows and ridges that run horizontally across the slope, acting as mini-barriers to water flow. Crop rows follow these contours. | Creates physical barriers (bunds or low walls) of soil or stones along the contours. These bunds can be continuous or have gaps with cross-ties to create micro-catchments. |
| Application | Primarily focused on agricultural land for cultivating crops. | Used in agricultural land, pastureland, and even for reforestation to manage water and soil erosion. Can be applied in lower rainfall areas. |
| Mechanism | The contour furrows act as small dams, holding water and allowing it to soak into the soil. Tilling across the slope disrupts the direct downhill flow of water. | The bunds physically block or slow down the flow of water, allowing it more time to infiltrate the soil behind the bund. |
| Scale | Involves working the entire field along the contours. | Involves constructing linear barriers across the slope. The area between bunds is still farmed or managed. |
| Suitability | Effective on gently to moderately sloping land. | Suitable for marginal, sloping, and hilly land, often in lower rainfall areas. Can be used on steeper slopes with appropriate design. |
Question 8.
What do you understand by controlled grazing ?
Ans:
Controlled grazing is a planned system of moving livestock between fenced pasture sections (paddocks) for short grazing periods, followed by rest for plant regrowth. This prevents overgrazing, improves pasture health and productivity, and often involves managing stocking density and adapting plans based on conditions. It’s a strategic alternative to continuous, unrestricted grazing.
E. Answer the following questions in one or two paragraphs
Question 1.
What is gradation? Describe the two processes involved in gradation.
Ans:
Gradation is the natural leveling of Earth’s surface. It involves degradation, the wearing down of high areas through weathering, erosion, and mass movement, and aggradation, the building up of low areas through the deposition of transported materials by water, wind, and ice. These opposing processes work to create a more uniform landscape over time.
Question 2.
Describe the process that leads to exfoliation.
Ans:
Exfoliation occurs through the gradual detachment of curved or sheet-like layers from a rock’s surface. The primary driver is pressure release, which happens as overlying rock erodes away, allowing the now-exposed rock to expand outward. This expansion is greater in the outer layers, creating stress that leads to fracturing and the eventual shedding of these layers. Cyclical heating and cooling of the rock surface, especially in environments with extreme temperature variations, also contributes by causing differential expansion and contraction between the outer and inner parts of the rock. Additionally, the expansion of ice in surface-parallel cracks (a form of frost wedging) and the swelling of minerals due to chemical weathering (like hydration) can exert outward forces that facilitate the peeling process. This layered removal ultimately results in the formation of smooth, rounded rock formations, often referred to as exfoliation domes.
Question 3.
Discuss the role of water in the process of chemical weathering.
Ans:
Water is the primary driver of chemical weathering due to its unique properties. As a solvent, it dissolves many minerals. Water also acts as a medium for reactions like carbonation, where dissolved carbon dioxide forms carbonic acid that dissolves rocks like limestone. In hydration, water molecules are incorporated into mineral structures, causing expansion and weakening. Finally, water facilitates oxidation by transporting oxygen and participating in the formation of oxides. Essentially, water’s ability to dissolve, react, and act as a medium makes it indispensable for a wide range of chemical processes that decompose rocks and shape the Earth’s surface.
Question 4.
How do animals and plants assist in weathering?
Ans:
Animals facilitate weathering primarily through physical means, such as the fragmentation of rock and soil via burrowing, tunneling, and the pressure exerted by trampling. Certain marine animals also contribute by boring into softer rocks for shelter. Plants, on the other hand, contribute through both physical and chemical processes. The growth of plant roots exerts significant pressure within rock fissures, leading to root wedging and physical fracturing. Additionally, plants and decaying organic matter release organic acids and chelating compounds into the surrounding environment, which chemically dissolve minerals in rocks. Organisms like lichens and mosses that grow directly on rock surfaces also contribute to weathering through both the physical effects of their growth and the chemical action of the acids they produce. These biological activities, combined with abiotic weathering processes, play a crucial role in the breakdown of rocks and the formation of soil.
Question 5.
What is meant by the terms ‘soil erosion’ and ‘soil conservation’?
Ans:
Soil Erosion: This refers to the process by which the topsoil layer of the Earth’s surface is worn away and transported to another location. This removal is primarily caused by natural forces such as water (rain, runoff, waves), wind, and ice (glaciers). However, human activities like deforestation, unsustainable agriculture, overgrazing, and construction significantly accelerate soil erosion rates. Soil erosion leads to a loss of fertile land, reduced agricultural productivity, water pollution from sediment runoff, and land degradation.
Soil Conservation: This encompasses the various methods and practices implemented to prevent or reduce soil erosion and maintain or improve the quality and productivity of soil. It involves a range of techniques aimed at protecting the soil surface, managing water flow, maintaining soil structure and organic matter content, and promoting healthy vegetation cover. The goal of soil conservation is to ensure the long-term sustainability of soil resources for agriculture, ecosystem health, and environmental quality.
Question 6.
Why is soil conservation important ? Give three reasons.
Ans:
Ensuring Food Security: Healthy soil is the foundation of agriculture. It provides essential nutrients, water retention, and physical support for plant growth. Soil erosion and degradation lead to a decline in soil fertility, directly impacting crop yields and threatening our ability to produce enough food for a growing global population. Conserving soil ensures the long-term productivity of agricultural lands, safeguarding food security and stable food prices.
Protecting Water Resources and Quality: When soil is eroded, sediment, along with associated pollutants like fertilizers and pesticides, runs off into rivers, lakes, and reservoirs. This sedimentation can harm aquatic ecosystems, reduce water storage capacity, increase turbidity, and contaminate drinking water sources. Soil conservation practices help to minimize this runoff, protecting the quality and availability of clean water for both human consumption and ecological health.
Maintaining Ecosystem Health and Biodiversity: Soil is a complex and dynamic ecosystem teeming with a vast array of microorganisms, invertebrates, and plant roots that are essential for nutrient cycling, decomposition, and overall ecosystem functioning. Soil erosion and degradation disrupt these intricate relationships, leading to a loss of biodiversity and a decline in ecosystem health. Soil conservation helps to maintain healthy soil ecosystems, which in turn support a wider range of plant and animal life both above and below ground.
Question 7.
Explain any two methods of soil conservation briefly.
Ans:
1. Contour Farming: Farmers plow and plant crops along the natural curves of a hillside, not straight up and down. These horizontal rows act like tiny dams, slowing rainwater flow, increasing absorption, and minimizing soil washing away. It’s best for gentle slopes.
2. Terracing: On steep hills, farmers build a series of flat steps, like giant stairs. Each step catches rainwater, letting it soak in instead of running downhill and taking soil with it. Excess water drains safely. This is a very effective way to farm sloped land without losing soil.
F. Make a chart for your classroom showing the causes of different types of weathering.
Ans:
Do it yourself.
G. Form pairs or groups of three or four students and discuss, with examples, how we depend directly and indirectly on soil.
Ans:
Do it Yourself with the help of teacher.
H. Picture Study
Question 1.
What is this farming method called ?
Ans:
Terrace farming.
Question 2.
Mention any two other methods that help in controlling soil erosion.
Ans:
Construction of mud walls, ploughing fields in circles, levelling of fields can also prevent soil erosion.
