BE8504 Soil Science
Experiment 8 - Loss On Ignition
To determine the concentration of organic contaminants in soils by using the Loss in ignition method.
The quantity of organic matter in soil is determine by either direct or indirect methods. Direct method target the destruction of all organic matter, after which the loss in weight of soil is taken as the organic content. Two methods are commonly used to achieve destruction of organic matter:
Oxidation of organic matter with hydrogen peroxide (H2O2).
Ignition of soil at high temperature.
The H2O2 method may not result in the oxidation of all organic matter, thereby underestimating the organic content of the soil. On the other hand, the ignition method may also destroy some inorganic constituents, thereby overestimating the organic content of the soil. The organic content loss on ignition is given by = (m2-m3)/(m2-m1) x 100% Where m1 - Mass of crucible (g)
m2 - Mass of crucible + sample (g)
m3 - Mass of crucible + sample after heating (g)
- Drying oven, 105-110˚C
- Balance accurate to 0.001g
- Furnace - Silica or porcelain crucible
- Long tongs
1.Prepare a representative sample of about 50g of oven-dried organic soil.
2.Clean, dry and weigh the crucible (m1).
3.Place the dried soil in the crucible and weigh it (m2).
4.Place the crucible in the furnace and heat to 500˚C for 30 min.
5.Allow the crucible to cool in the desiccators and weigh it (m3).
6.Repeat the above steps for two more samples.
Soil type: Fertilized soil .
Temperature required to heat up the crucible: 500˚C .
Sample 1 Sample 2 Sample 3 Crucible no....
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