======Soil Water Holding Capacity======


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**Alternative titles:** Soil Porosity and Water Retention
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====Summary====                   
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====Procedure====  
  -Spread a collected soil sample evenly on a baking tray to a depth of about 0.5 cm.  
  -Place the tray in an oven or incubator set at 105°C and dry the soil completely.  
  -Using heatproof gloves, remove the tray and allow the soil to cool to room temperature on a heatproof surface.  
  -Weigh an empty 100 mL beaker and then zero the scale.  
  -Add about 50 g of the dried soil into the beaker and record the exact initial weight.  
  -Set up a funnel on a retort stand and insert filter paper inside the funnel.  
  -Transfer the 50 g of dry soil into the funnel.  
  -Place an empty 100 mL beaker beneath the funnel to collect any drained water.  
  -Measure 100 mL of water in a measuring cylinder and pour it slowly over the soil in the funnel.  
  -Cover the funnel top with cling wrap to minimize evaporation, and poke small holes with a toothpick to maintain air pressure.  
  -Leave the setup overnight to allow drainage.  
  -After draining, weigh the hydrated soil (still in the filter paper) and record the final weight.  
  -Calculate the amount of water retained by subtracting the initial soil weight from the final soil weight.  
  -Determine the water holding capacity as a percentage.
  -Repeat for other soil types.




====Links==== 
Soil Water Holding Capacity Determination Practical Experiment - ThomasTKtungnung: 
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Water holding capacity - Chemistry with Mrs V: 
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📄 Water holding capacity of soil experiment - Gene Technology Access Centre: [[https://gtac.edu.au/wp-content/uploads/2022/02/Transpiration-water-holding-capacity-of-soil-experiment-v1.0.pdf]]\\

====Variations====
  *Test different types of soil (clay, sand, loam) to compare water holding capacities.  
  *Use different soil particle sizes or organic content levels to see how they affect results.

====Safety Precautions====
  *Use heatproof gloves when handling the hot oven, trays, or soil.  
  *Ensure all equipment removed from the oven is placed on a heatproof mat.  
  *Do not leave the oven unattended while drying soil.  
  *Avoid touching hot metal equipment directly.  
  *Handle glassware carefully to prevent breakage.  
  *Clean and dry all equipment thoroughly after use.




====Questions to Consider====
  *Which type of soil would you expect to have the highest water holding capacity, and why? (Clay soils generally hold more water due to smaller particles and greater surface area.)  
  *Why must the soil be completely dry before starting the experiment? (To ensure accurate measurement of only the water added and retained.)  
  *What effect might organic matter have on the soil’s water holding capacity? (Organic matter increases water retention by improving porosity and binding water molecules.)  
  *How could soil structure influence plant growth and transpiration rates? (Soils with better water retention provide more consistent moisture for roots, supporting photosynthesis and transpiration.)  
  *Why is it important to prevent evaporation during the draining period? (To ensure any loss of water measured is due to drainage, not evaporation.)