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www.GOALias.blogspot.comthe time when you start pouring water.When all the water has percolatedleaving the pipe empty, note the timeagain. Be careful not to let the waterspill over or run down on the outside ofthe pipe while pouring. Calculate therate of percolation by using thefollowing formula:amount of water (mL)percolation rate (mL/min) = percolation time (min)StandDropsBoiling tubeSoil sampleFor example, suppose that for acertain sample, it took 20 minutes for200 mL to percolate. So,200 mLrate of percolation = = 10 mL/min20 minCalculate the rate of percolation inyour soil sample. Compare your findingswith others and arrange the soil samplesin the increasing order of the rate ofpercolation.9.5 M9.5 MOISTUREIN SOILHave you ever passed through afarmland during a hot summer day?Perhaps you noticed that the air abovethe land is shimmering. Why is it so?Try out this activity and find the answer.Activity 9.5Take a boiling tube. Put two spoonfullsof a soil sample in it. Heat it on a flame(Fig. 9.6) and observe it. Let us find outwhat happens upon heating.Do you see water drops any where?If yes, where did you find them?On heating, water in the soilevaporates, moves up and condenses onthe cooler inner walls of the upper partof the boiling tube.BurnerFig. 9.6 Removing moisture from the soilOn a hot summer day, the vapourcoming out of the soil reflect the sunlightand the air above the soil seems toshimmer.After heating the soil, take it out ofthe tube. Compare it with the soil whichhas not been heated. Note the differencebetween the two.9.6 ABSORPTIONOF WATERBY SOILDo all the soils absorb water to the sameextent? Let us find out.Activity 9.6Take a plastic funnel. Take a filter paper(or a piece of newspaper sheet), fold andplace it as shown in the figure. Weigh50g of dry, powdered soil and pour itinto the funnel. Measure a certainamount of water in a measuring cylinderand pour it drop by drop on the soil.You can use a dropper for this purpose.Do not let all the water fall at one spot.101SOIL101