Soil FOR CLASS 7 AND ABOVE

Soil

1. What is soil ?? The uppermost layer of the earth is known as soil. This layer consists of sand, mud, and rock particles. What is humus?? Consists of dead and decayed plants and animal remains called humus.

2. What Is weathering?? The breaking down of rocks is known as Weathering Wind , water , frost helps in transporting of soil to places. There are two types of weathering : Physical weathering Chemical weathering

3. Physical weathering. Physical weathering is the process of breaking of rocks into smaller pieces. These change do not involve any characteristic change in the original rock . These are caused by the -Temperature change, -frost

4. Chemical weathering Chemical weathering is the process which exists of mineral are broken down into mineral components. Water is the main agents used in this Process.

5. soil What is weather?? The weather conditions prevailing in an area in general or over a long period. Climate effects by the rain , wind , temperature of an place

6. Characteristic of the parent rock Characteristic of the parent rock also determines the kind of soil formed. Parent rock refers to the original rock from which something else was formed. It is mainly used in the context of soil formation where the parent rock normally has a large influence on the nature of the resulting soil.

7. What are the main factors affecting soil formation?? Climate Characteristic of the parent rock Slope of land Climate : The weather conditions like the rain , wind ,etc plays an important role in loosing the soil. Increasing of pressure can also cause make the rocks to crack .Rocks are also worn down by wind. Soil formation is faster in hot and slow in winter season.

8. Soil formation stages step 1: Weathering is the physical or chemical process. Step 2: small rocks continue to undergo weathering, causing large pieces of parential rocks. Step 3: minerals and salts seep deeper into the ground along with water.

9. Humus and topsoil Humus is the organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms . is the uppermost layer of soil. this layer consists of humus and fine particles of dust and sand.

10. Horizon Contains weathered rocks. It is very difficult to dig more than this layer. the line at which the earth's surface and the sky appear to meet. ___________________________________ Bedrock The lower most layer and consists of parent rock. This layer is mainly consists of soil. _____________________________________

11. this layer is also soft and can hold water O horizon lies just above this top soil which is rich in organic matter. ________________________________ Sub soil Subsoil is rich in minerals that sweep down along with the water . It also consists of fine particles of soil. ________________________________

12. Parental rock undergoing change what is regolith : the layer of solid material covering the bedrock of a planet.

13. Humus Top soil Sub soil Bedrock

14. Particles size of construction Particles Diameter Clay Less than 0.002 Slit 0.002 – 0.05 Sand 0.05 – 2.00 Fine bebbles 2.00 – 5.00 Medium pebbles 5.00 – 20.00 Coarse pebbles 20.00 - 75.00

15. Properties of soil The 3 properties of soil are : Absorption of soil. Moister of soil. Percolation of water. Percolation is the process of a liquid slowly passing through a filter.

16. Soil erosion Soil compaction, low organic matter, loss of soil  structure, poor internal drainage, salinisation and soil acidity problems are other serious  issues. Surface water runoff occurs whenever there is excess water on a slope that cannot be absorbed into the soil or is trapped on the surface.

17. Sandy soil : Sand soils are often dry, nutrient deficient and fast-draining. They have little ability to transport water from deeper layers through capillary transport. tillage of sandy soils in the spring should be kept to a minimum in order to retain moisture in the seedbed . meaning of tillage :the preparation of land for growing crops. the preparation of land for growing crops.

18. Clayey soil Clay  is a fine-grained natural rock or soil material that combines one or more clay minerals with traces of metal  variable amounts of water trapped in the mineral structure. Depending on the content of the soil, clay can appear in various colours , from white to dull gray or brown to a deep orange-red.

19. Loamy soil Loam  is soil composed mostly of  sand and a smaller amount of  clay. Use in farming !! Loam is considered ideal for gardening and agricultural uses because it retains nutrients well and retains water while still allowing excess water to drain away

20. Pictures of 1.sandy soil , 2.clayey soil , 3.loamy soil. 1 2 3

21. How to prevent soil erosion Deforestation Overgrazing Flood and heavy rainfall Improper farming Plant more trees and cut less trees. Overgrazing in a same patch of land should be avoided. Terrace farming should be adopted in hilly areas.