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(3) water, at ana parr Si 8 Water, , Ans. (c) In addition to the, , , rock particles, the, i: Minerals, Organic matter, air and water,, : water holding is the h, , Mi on Capacity ighest in, , (b) clayey soil, , (c) loamy soil, , (a) mixture of sand and loam, , Ans. (b) The water holdi i, highest in clayey soil, cere ae, , Column | Column 1!, (a) A home for living, isms, , (i) Large particles, , , , (v) Lesser amount of, humus, , (e) Clayey soil, , Ans. (a)-(ii), (b)-(iii), (c)-(i), (d)-(v),(e)-(iv),, 4. Explain how soil is formed., Ans. Soil formation is a slow Process which, occurs in following two steps, (i) Weathering of rocks is the breakdown of, rocks into small particles by the action of, air, wind and water,, (ii) These small particles mix with humus, (organic matter) and form soil., , 5. How is clayey soil useful for crops?, , Ans. Clayey soil has an important, characteristic. It can retain water and moisture, and are rich in humus. Therefore, it is suitable for, growing cereals like wheat, gram and paddy., , 6. List the differences between clayey soil and, sandy soil., , » Sketch the ross-section of soil and label the Various, , » Razia conducted an experiment in the field related, , + Explain how soil pollution and soil erosion could be, , der, , Ans. Differences between ci, , ayey soil and Sandy Soi], , , , , , , , are, : Clayey soil Sandy soi), articles are of very small size. Particles are of quite ~, vs ‘ large size, ‘articles are lightly packed P,, together packed,, No air is present between Well aerated, , Particles, , It can fetain water for long time it Cannot hold water, Water does Not drain easily Water drains easily, , It is fertile Itis not fertile, , layers,, Ans. Labelled sketch Of the cross-section of soil is, , } Achorizon (topsoil, } B-horizon (subsoil), , , , , C-horizon (partially weathered rock), Bedrock, , to the rate of percolation, She observed that it took, 40 mins for 200 mL of water to Percolate through, the soil sample. Calculate the rate of percolation., Ans. Given, Time = 40 mins, , Volume of water = 200 mL, , So, rate of percolation, , Percolation time (min) = 40 — eiocron, , Therefore, percolation rate of water =5 mL/min., , prevented., , Ans. Preventions of soil Pollution can be done by, (i) using manures instead of synthetic fertilisers., (ii) using natural pesticides., , (lil) avoiding dumping of Polythene and plastics in, soil., , (iv) treating industrial waste before releasing it in the, soil., , Preventions of soil erosion can be done by, (i) afforestation that is large scale Planting in place, , cut down forests., , (ii) avoiding overgrazing of grasslands., , (iii) terrace farming and other better farming methods, in hilly areas,