com www.GOALias.blogspot.com www.GOALias ... - fun learning

www.GOALias.blogspot.comI wonder why I found somepieces of plastic articles andpolythene bags in the soil samplecollected from the roadside andthe garden.and then add a handful of soil to it. Stirit well with a stick to dissolve the soil.Now let it stand undisturbed for sometime (Fig. 9.2). Afterwards, observe it andanswer the following questions:Polythene bags and plastics pollutethe soil. They also kill the organismsliving in the soil. That is why there isa demand to ban the polythene bagsand plastics. Other substances whichpollute the soil are a number of wasteproducts, chemicals and pesticides.Waste products and chemicals shouldbe treated before they are releasedinto the soil. The use of pesticidesshould be minimised.I want to know whether thesoil from a field can be usedto make toys?9.2 S9.2 SOILPROFILESoil is composed of distinct layers.Perform the following activity to find outhow these layers are arranged.Activity 9.2Take a little soil. Break the clumps withyour hand to powder it. Now take a glasstumbler, three quarters filled with water,Fig. 9.2 Layers of soilhumuswaterclaysandgravel• Do you see layers of particles ofdifferent sizes in the glass tumbler?• Draw a diagram showing these layers.• Are there some dead rotting leavesor animal remains floating on water?The rotting dead matter in the soil iscalled humus.You probably know that the soil isformed by the breaking down of rocksby the action of wind, water and climate.This process is called weathering. Thenature of any soil depends upon therocks from which it has been formed andthe type of vegetation that grows in it.A vertical section through differentlayers of the soil is called the soil profile.Each layer differs in feel (texture),SOIL9797