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www.GOALias.blogspot.comand can hold plenty of air, are moresuitable.Crops such as wheat are grown inthe fine clayey soils, because they arerich in humus and are very fertile. Findfrom your teachers, parents and farmersthe type of soils and crops grown in yourarea. Enter the data in the followingTable 9.2:Which kind of soil would be mostsuitable for planting rice? Soil with ahigher or lower rate of percolation?Table 9.2S. No. Type of soilCrop grown1. Clayey Wheat …………2.3.KeywordsClayeyHumusLoamyPercolationMoistureSandyWater retentionWhat is the differencebetween rate of percolation andthe amount of water retained?Boojho, you seem to haveforgotten what you readearlier. Go and reread thelesson again and you will findthe answer.Soil erosionThe removal of land surface by water,wind or ice is known as erosion. Plantroots firmly bind the soil. In theabsence of plants, soil becomes loose.So it can be moved by wind and flowingwater. Erosion of soil is more severein areas of little or no surfacevegetation, such as desert or barelands. So, cutting of trees anddeforestation should be prevented andeffort should be made to increase thegreen areas.What you have learnt• Soil is important for life on the earth.• Soil profile is a section through different layers of the soil, Various layersare called horizons.• Soil is of different types: clayey, loamy and sandy.• Percolation rate of water is different in different types of soil. It is highestin the sandy soil and least in the clayey soil.• Different types of soils are used to cultivate different types of crops. Clayand loam are suitable for growing wheat, gram and paddy. Cotton isgrown in sandy loam soil.104SCIENCE