Soils | Class 7 | Geography | Chapter 7 | Maharashtra State Board
Explore the fascinating world of soil and its formation factors, including parent rock, regional climate, biotic material, and time. Journey through geographical landscapes like coarse soil, regur (black soil), laterite soil, alluvial soil along the coastal strip, and yellow-brown soil. Understand the challenges of soil erosion and degradation, and discover effective conservation methods like weirs, afforestation, continuous contour trenches (CCT), and contour bunding. Join us to unravel the secrets beneath the surface and learn how soil sustains life and ecosystems.
Questions & Answers
Q.1. Complete the following table.
| Factor/Process | Role in the formation of soil |
1. | Parent rock | The process of weathering, which involves the physical and chemical breakdown of parent rock, is critical for soil formation. Over time, rainwater, wind, ice, and living organisms can wear away the rock’s surface, creating smaller particles that eventually become soil. |
2. | Regional climate | Regional climate affects soil formation by influencing weathering: warm and wet conditions accelerate chemical weathering, while cold climates often lead to physical weathering. |
3. | Organic material | Organic material, like decaying plants and animals, plays a vital role in soil formation by contributing nutrients and creating a favorable environment for microbial activity. |
4. | Microorganisms | Microorganisms, such as bacteria and fungi, are essential in soil formation as they break down organic matter, releasing nutrients that plants need to grow. |
2. Why do the following occur?
1. To the west of Sahyadris, laterite soils are formed from the basalt rock. Ans. The formation of laterite soils to the west of the Sahyadris occurs because of the weathering of basalt rock. The basalt rock undergoes chemical processes in the warm and humid climate, leading to the development of laterite soils rich in iron and aluminium oxides.
2. Humus content in the soil increases. Ans. The increase in humus content in the soil occurs due to the decomposition of organic matter, such as plant and animal remains. As these materials break down, they contribute to the formation of humus, enriching the soil with nutrients and improving its fertility.
3. Soil formation process is faster in the equatorial climate. Ans. The soil formation process is faster in equatorial climates because of higher temperatures and abundant rainfall. The combination of warmth and moisture accelerates both physical and chemical weathering of rocks, leading to quicker soil development.
4. The salinity of the soil increases. Ans. The increase in soil salinity occurs when there is an accumulation of salts in the soil, often due to factors such as high evaporation rates and insufficient drainage. As water evaporates, salts are left behind, gradually raising the salinity levels in the soil.
5. Rice is the staple diet of the people from Konkan. Ans. The preference for rice as a staple diet in Konkan occurs due to the region's suitable climate and topography for rice cultivation. The availability of water and favourable growing conditions make rice a prominent and reliable food source for the people in Konkan.
6. Soil erosion.
Ans. Soil erosion occurs when wind or water removes the top layer of soil. Factors like deforestation and improper land use can contribute to weakened soil structure, making it more susceptible to erosion.
7. Soil degradation.
Ans. Soil degradation occurs when the quality of the soil declines due to factors like overuse, deforestation, or improper agricultural practices. This leads to a loss of fertility, reduced water retention, and diminished overall soil health.
3. Give information on -
1. Measures of soil conservation Ans. The following are the measures of soil conservation:
(i) Afforestation/Planting trees: Planting trees can help control soil erosion caused by wind and water. Tree roots hold the soil in place, and the vegetation helps reduce the impact of rain droplets on the soil surface, thereby reducing splash erosion.
(ii) Continuous contour trenches: Building continuous contour trenches across slopes can help check the velocity of water running downhill and reduce soil erosion. The water collected in these trenches can percolate into the ground, recharging groundwater aquifers and further reducing the risk of erosion.
(iii) Watershed Development Program: The government’s watershed development program has been successful in implementing measures such as constructing embankments along slopes and building continuous contour trenches (CCTs) along steep slopes. These steps have helped raise groundwater levels and reduce soil erosion.
(iv) Jalayukt Shivar: The Jalayukt Shivar scheme focuses on constructing farm bunds, intercepting waters from small streams, and connecting them to larger water bodies. By doing so, it helps reduce soil erosion caused by flowing water and promotes groundwater recharge.
2. Organic manures.
Ans. Organic manures are natural fertilizers derived from plant or animal sources. Examples include compost, animal dung, and green manure. They enhance soil fertility by providing essential nutrients, improving soil structure, and promoting beneficial microbial activity. Using organic manures supports sustainable agriculture practices and reduces reliance on synthetic chemicals.
3. Place where you will get the information about the suitability of a soil for a particular crop. Ans. (i) Department of Agriculture, Government of Maharashtra, Natural Resource Conservation Services, Soil Testing Laboratories, and Agricultural Universities.
These are indeed reliable sources for information about the suitability of soil for a particular crop. Government departments, conservation services, and agricultural universities often conduct research and provide guidance on soil characteristics and crop suitability.
(ii) Soil Testing: Soil testing is a crucial step in determining soil properties such as type, fertility, and pH. It provides essential information for assessing the suitability of soil for specific crops.
(iii) Analysis of Soil: After soil testing, the collected data is analyzed to understand the soil’s characteristics. This analysis forms the basis for providing information about the suitability of the soil for particular crops.
4. Importance of soils for plant growth. Ans. Soils are essential for plant growth because they provide support, nutrients, and water. Roots anchor plants, soils store nutrients, and water retention keeps plants hydrated.
4. Complete the following table with reference to soil.
| Action | Effect | Result (W.R.T. fertility) |
1. | Construction of embankments. | Protects soil from being washed away. | Protects fertility of soil. |
2. | Planting trees. | Wind speed decreased. | Protects fertility of soil. |
3. | Farm land is kept fallow for some period. | Helps to maintain the pH balance and increase the proportion of humus. | Increases the fertility of soil. |
4. | Regular use of organic manures, vermicompost and compost. | Humus content increased. | Increases the fertility of soil. |
5. | Trenches are dug across a slope. | Check the velocity of water running along the slopes. | Protects fertility of soil. |
6. | Litter is burnt in the farm. | Decreases the amount of organic material in soil. | Decreases the fertility of soil. |
7. | Decomposed vegetal litters, roots of plants and remains of animals. | Proves favourable for micro-organism | Increases the fertility of soil. |
8. | Excessive Irrigation | Salt content in the soil increases. | Decreases the fertility of soil |
9. | Chemical fertilizers used excessively. | Leads to the lowering of humus content in the soil. | Decreases the fertility of soil |
E X T R A
Q.1. Fill in the blanks.
1. Parent rock in a region is an important factor in soil. (Parent, Basalt, Granite)
2. The process of weathering depends on the climate of the region. (climate, weather, soil)
3. The basalt rock of the Deccan Plateau in Maharashtra turns into black soil after weathering. (granite, basalt, parent)
4. Fertile soils along the river beds give higher yields. (Infertile, Fertile, Coarse)
5. The biotic1 material comes from the decomposition of the remains of the plants and animals in that region. (biotic1, abiotic, pH)
6. Soil is a complete ecosystem. (Soil, Humus, weathered rocks)
7. Food crops like jowar and bajra are produced in the regur soils of Maharashtra Plateau. (regur, coarse, laterite)
8. The local agriculture produce determines the staple diet of the people. (staple, supplementary, secondary)
9. The proportion of humus is negligible in coarse soil. (coarse, black, laterite)
10. Planting trees can also control the velocity of the wind. (velocity, direction, temperature)
11. Rocks like granite or gneiss in South India give rise to red soil. (black, red, regur)
12. In the humid climate of western Sahyadris the leaching of basalt rocks leads to formation of lateritic soil. (black, lateritic, red)
13. The excessive spraying of chemicals and use of chemical fertilizers lead to soil degradation. (soil degradation soil fertility, soil powder)
2. Complete the following sentences:
1. The biotic material comes from _________ Ans. the decomposition of the remains of the plants and animals in that region.
2. Microorganisms and certain other organisms help decompose the dead remains of _________ Ans. organic materials.
3. Production of compost needs sufficient period of time and _________ Ans. elements like organic waste, water, heat, etc.
4. In the region of high rainfall and higher temperatures, _________ Ans. the process of soil formation is faster.
5. In regions of low temperatures and low rainfall the _________ Ans. soil formation takes more time.
6. High use of chemical fertilizers, insecticides _________ Ans. leads to the degradation of soils.
7. In the areas where the soil is not fertile, _________ Ans. vegetation is scanty.
8. When man realized that sowing of seeds in the soil leads to the growth of plants and yields crops, _________ Ans. he started using soil as a resource.
9. Excessive irrigation draws the salts from the soil upwards and _________ Ans. makes the soil saline and then unproductive.
10. Keeping the farmland fallow for some period and cultivating different crops alternatively is important _________ Ans. to help retain the fertility of soils.
3. Give one word for the following:
1. Soil formed due to weathering of basalt rock. Ans. Black soil
2. Soil formed due to the leaching of the basalt rock. Ans. Lateritic soil
3. Biotic material mixed into the soils. Ans. Humus
4. The excessive spraying of chemicals and use of chemical fertilizers. Ans. Soil degradation
5. The govt, scheme, work like construction of farm bunds, arresting waters of small streams, etc. Ans. Jalayukt Shivar.
4. Who am I?
1. I am a very important rock factor in soil formation. Ans. Parent rock
2. I form due to weathering of basalt rock. Jowar and Bajra mostly grow on this soil. Ans. Regur soil / Black soil
3. I am found in the hilltops of the western part of the Deccan plateau. Ans. Coarse soil
4. I am black in colour and have less organic components. Ans. Regur or Black soil
5. I am orange in colour and mostly found in the coastal belt of Konkan. Ans. Laterite soil
6. I am found at the mouth of the river in the western coastal strip. Ans. Alluvial soil of the coastal strip
7. I am mainly found in areas of extreme rainfall but not very useful for agriculture. Ans. Yellow brown soil
8. I am a method of soil conservation which controls the velocity of wind. Ans. Afforestation / planting trees
5. Answer the following questions in short:
1. What do you mean by ‘Soil’? Ans. "Soil" refers to the top layer of the Earth's surface, composed of a mix of minerals, organic matter, and air. It's where plants grow, and it provides essential support, nutrients, and water for their development.
2. What are the factors necessary for the soil formation? Ans. Soil formation is influenced by several factors:
Parent Material: The type of rock or sediment from which the soil forms.
Climate: Temperature and precipitation affect weathering and decomposition processes.
Organisms: Plants, animals, and microorganisms contribute to the decay of organic matter.
Topography: The landscape's slope and shape influence water drainage and erosion.
Time: Soil development is a gradual process that takes years or even centuries.
These factors interact to shape the unique characteristics of different soils.
3. What is leaching? Ans. Leaching is the process where water moves through soil, dissolving and carrying away minerals and nutrients. It can impact soil fertility as essential elements may be washed away, affecting plant growth.
4. What is Humus? Ans. Humus is the dark, organic material in soil formed by the decomposition of plant and animal matter. It improves soil structure, retains water, and provides essential nutrients for plant growth.
5. What leads to the degradation of soils? Ans. Soil degradation occurs due to factors like:
Erosion: Wind or water removing the topsoil.
Deforestation: Removing trees reduces soil stability.
Overgrazing: Excessive grazing by animals damages vegetation.
Poor Agricultural Practices: Unhealthy farming methods deplete soil nutrients.
Pollution: Contamination by chemicals harms soil quality.
These factors contribute to the deterioration of soil health and productivity.
6. What led to record agricultural production? Ans. Record agricultural production is boosted by:
Technology: Improved machinery and precision farming enhance efficiency.
Inputs: Fertilizers enrich soil, and pesticides protect crops.
Crop Choices: High-yield and genetically modified crops increase output.
Education: Access to modern farming methods optimizes practices.
Infrastructure: Improved transport and storage reduce losses, collectively elevating productivity.
7. What is soil erosion? Ans. Soil erosion is when the earth's surface wears away because of natural forces like wind and rain. It happens when the ground is left unprotected and vulnerable to weather conditions. Over time, this can cause the soil to become thinner and less fertile, making it harder for plants to grow. It can also cause problems for people, like mudslides and flooding.
8. What helps to maintain the pH balance of the soil? Ans. Adding organic matter, like compost, helps maintain soil pH balance by acting as a buffer and preventing rapid changes. Additionally, using lime can raise pH in acidic soils, while sulfur can lower pH in alkaline soils. Regular soil testing guides appropriate amendments for pH maintenance.
6. Why do the following occur:
1. Rice is the staple diet of the people from Konkan. Ans. Rice is a staple diet in the Konkan region due to its suitable climate and abundant water resources. The region's coastal and hilly geography, coupled with ample rainfall, creates favourable conditions for rice cultivation. The availability of water for irrigation and the region's agrarian traditions contribute to the prominence of rice as a staple food in Konkan.
7. Give geographical reasons:
1. Planting trees is necessary to conserve the soil. Ans. Planting trees is crucial for soil conservation because tree roots help bind the soil, preventing erosion. Trees also enhance soil structure, increase water absorption, and contribute organic matter, improving overall soil health. This helps in sustaining fertile soil for agriculture and maintaining ecosystem balance.
2. Continuous contour trenches are constructed along the slopes. Ans. Continuous contour trenches are built along slopes to reduce soil erosion and manage water runoff effectively. These trenches act as barriers, slowing down water flow and allowing it to infiltrate into the soil. By following the contour lines of the land, these trenches help in conserving soil, preventing erosion, and promoting sustainable agriculture practices.
3. It is advisable to use organic manures, vermicompost and compost regularly. Ans. Using organic manures, vermicompost, and compost regularly is advisable because they improve soil structure, provide essential nutrients to plants, and enhance water retention. These organic amendments also promote beneficial microbial activity in the soil, fostering a healthy and sustainable environment for plant growth.
4. There emerged competition among the people to discover fertile lands and settle there. Ans. Competition to discover fertile lands and settle there emerged due to the desire for better agricultural opportunities and resources, including fertile soil for productive farming. Fertile lands offer the promise of higher crop yields, making them attractive for settlement as they support thriving communities and agricultural economies.
5. There was a rise of Indus civilization. Ans. The rise of the Indus Civilization was facilitated by the fertile and well-watered Indus River Valley, which supported agriculture. The availability of abundant resources from the river, such as water for irrigation and transportation, contributed to the development of sophisticated urban centers and a flourishing civilization in the region.
6. Countries like Saudi Arabia, Qatar, Oman, etc., fulfil their requirements by importing food from other countries. Ans. Countries like Saudi Arabia, Qatar, Oman, etc., import food to meet their needs because they have limited arable land and face challenges like water scarcity. Importing food ensures a stable food supply and meets the demands of their growing populations, allowing them to access a diverse range of products from countries with more favourable agricultural conditions.
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